Renamed support->viewpager, removed old deprecated code

Fixes #582

.travis.yml

@@ -3,8 +3,8 @@ language: android
 android:
   components:
     - tools
-    - build-tools-24.0.3
-    - android-25
+    - build-tools-28.0.3
+    - android-28
     - extra-android-m2repository
   licenses:
     - '.+'
@@ -31,5 +31,5 @@ sudo: false
 
 env:
   global:
-    - secure: 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
-    - secure: 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
+    - secure: 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
+    - secure: 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

CONTRIBUTING.md

@@ -0,0 +1,70 @@
+# Community Contribution Guidelines
+
+As the creators and maintainers of this project, we want to ensure that the project lives and continues to grow. Not blocked by any singular person's computer time. One of the simplest ways of doing this is by encouraging a larger set of shallow contributors. Through this, we hope to mitigate the problems of a project that needs updates, but there is no-one who has the power to do so.
+
+#### Development Process
+
+We maintain two permanent, protected branches: `master` and `development`.
+
+`master` is for the current release. It has already been distributed to jcenter and can't be modified at this point (except for docs that may be incorrect for the current release!).
+
+`development` is where we stage work for the *next* release. Pull requests should be directed to this branch.
+
+When working on a new feature or fix that may span multiple commits, please do so in a feature branch (ex: `feature/my_cool_thing`). Please clean up these feature branches once merged into `development`.
+
+When a new version is ready to be released, please create a pull request to merge `development` into `master`, named something like "Release 10.0". Then we can have some final discussion before we merge it into `master` and push the release out to the public.
+
+Since `development` is a *shared* branch, it is important not to ever rebase this branch onto `master`. If a bug fix is applied to `master` it can be merged into `development` using good old simple `git checkout development && git merge master`. Yes this will clutter the history a little bit, but it also provides important context to know how/when a patch was applied. Merge commits can be considered necessary historical data, not warts on an idealized history graph.
+
+#### Testing
+
+To run tests locally, just run `./gradlew test`. Tests should always be run before pushing anything to the repo.
+
+#### Ownership
+
+If you get a merged pull-request of substance (ie not just a typo fix), then you are eligible for push access to this repo. Simply request access via a new GitHub issue.
+
+Offhand, it is easy to imagine that this would make code quality suffer, but in reality it offers fresh perspectives to the codebase and encourages ownership from people who are depending on the project. If you are building a project that relies on this codebase, then you probably have the skills to improve it and offer valuable feedback. At the end of the day, there isn't too much risk in this, as the `master` branch is still locked, and jcenter access is still being restricted.
+
+Everyone comes in with their own perspective on what a project could/should look like, and encouraging discussion can help expose good ideas sooner.
+
+#### Why do we give out push access?
+
+It can be overwhelming to be offered the chance to wipe the source code for a project. Do not worry, we do not let you push to master. All code is peer-reviewed, and we have the convention that someone other than the submitter should merge non-trivial pull requests.
+
+As a contributor, you can merge other people's pull requests, or other contributors can merge yours. You will not be assigned a pull request, but you are welcome to jump in and take a code review on topics that interest you.
+
+This project is not continuously deployed, there is space for debate after review too. Offering everyone the chance to revert, or make an amending pull request. If it feels right, merge.
+
+#### How can we help you get comfortable contributing?
+
+It is normal for a first pull request to be a potential fix for a problem, and moving on from there to helping the project's direction can be difficult. We will try to help contributors cross that barrier by offering good first step issues. These issues can be fixed without feeling like you are stepping on toes. Ideally, these are non-critical issues that are well defined. They will be purposely avoided by mature contributors to the project, to make space for others.
+
+We aim to keep all project discussion inside GitHub issues. This is to make sure valuable discussion is accessible via search. If you have questions about how to use the library, or how the project is running - GitHub issues are the goto tool for this project.
+
+#### Our expectations on you as a contributor
+
+To quote [@alloy](https://github.com/alloy) from [this issue](https://github.com/Moya/Moya/issues/135):
+
+> Do not ever feel bad for not contributing to open source.
+
+We want contributors to provide ideas, keep the ship shipping and to take some of the load from others. It is non-obligatory; we’re here to get things done in an enjoyable way. :trophy:
+
+The fact that you will have push access will allow you to:
+
+- Avoid having to fork the project if you want to submit other pull requests, as you will be able to create branches directly on the project.
+- Help triage issues and merge pull requests.
+- Pick up the project if other maintainers move their focus elsewhere.
+
+It is up to you to use those superpowers or not though 😉
+
+If someone submits a pull request that is not perfect, and you are reviewing, it is better to think about the PR's motivation rather than the specific implementation. Having braces on the wrong line should not be a blocker. Though we do want to keep test coverage high, we will work with you to figure that out together.
+
+#### What about if you have problems that cannot be discussed in a public issue?
+
+[Eric Kuck](https://github.com/erickuck) has a contactable email on his GitHub profile, and is happy to talk about any problems.
+
+#### This is a different way to handle open source! Where did it come from?
+
+The original source of this document can be found at [https://github.com/moya/contributors](https://github.com/moya/contributors).
+

README.md

@@ -1,11 +1,11 @@
-[![Travis Build](https://travis-ci.org/bluelinelabs/Conductor.svg)](https://travis-ci.org/bluelinelabs/Conductor) [![Android Arsenal](https://img.shields.io/badge/Android%20Arsenal-Conductor-brightgreen.svg?style=flat)](http://android-arsenal.com/details/1/3361) [![Javadocs](http://javadoc.io/badge/com.bluelinelabs/conductor.svg)](http://javadoc.io/doc/com.bluelinelabs/conductor)
+[![Travis Build](https://travis-ci.com/bluelinelabs/Conductor.svg)](https://travis-ci.com/bluelinelabs/Conductor) [![Android Arsenal](https://img.shields.io/badge/Android%20Arsenal-Conductor-brightgreen.svg?style=flat)](http://android-arsenal.com/details/1/3361) [![Javadocs](http://javadoc.io/badge/com.bluelinelabs/conductor.svg)](http://javadoc.io/doc/com.bluelinelabs/conductor)
 
 # Conductor
 
 A small, yet full-featured framework that allows building View-based Android applications. Conductor provides a light-weight wrapper around standard Android Views that does just about everything you'd want:
 
-              |  Conductor
-------|------------------------------
+|           |  Conductor  |
+|-----------|-------------|
 :tada: | Easy integration
 :point_up: | Single Activity apps without using Fragments
 :recycle: | Simple but powerful lifecycle management
@@ -20,47 +20,47 @@ Conductor is architecture-agnostic and does not try to force any design decision
 ## Installation
 
 ```gradle
-compile 'com.bluelinelabs:conductor:2.0.7'
+implementation 'com.bluelinelabs:conductor:3.0.0-rc3'
 
-// If you want the components that go along with
-// Android's support libraries (currently just a PagerAdapter):
-compile 'com.bluelinelabs:conductor-support:2.0.7'
+// If you want AndroidX Transition change handlers:
+implementation 'com.bluelinelabs:conductor-androidx-transition:3.0.0-rc3'
+
+// If you want a PagerAdapter for ViewPager:
+implementation 'com.bluelinelabs:conductor-viewpager:3.0.0-rc3'
 
 // If you want RxJava lifecycle support:
-compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.7'
+implementation 'com.bluelinelabs:conductor-rxlifecycle:3.0.0-rc3'
 
 // If you want RxJava2 lifecycle support:
-compile 'com.bluelinelabs:conductor-rxlifecycle2:2.0.7'
+implementation 'com.bluelinelabs:conductor-rxlifecycle2:3.0.0-rc3'
+
+// If you want RxJava2 Autodispose support:
+implementation 'com.bluelinelabs:conductor-autodispose:3.0.0-rc3'
+
+// If you want Controllers that are Lifecycle-aware (architecture components):
+implementation 'com.bluelinelabs:conductor-archlifecycle:3.0.0-rc3'
 ```
 
-SNAPSHOT:
+**SNAPSHOT**
 
-```gradle
-compile 'com.bluelinelabs:conductor:2.0.6-SNAPSHOT'
-compile 'com.bluelinelabs:conductor-support:2.0.6-SNAPSHOT'
-compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.6-SNAPSHOT'
-compile 'com.bluelinelabs:conductor-rxlifecycle2:2.0.6-SNAPSHOT'
-```
-
-You also have to add the url to the snapshot repository:
+Just use `3.0.1-SNAPSHOT` as your version number in any of the dependencies above and add the url to the snapshot repository:
 
 ```gradle
 allprojects {
   repositories {
-    ...
-
     maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
+  }
 }
 ```
 
 ## Components to Know
 
-              |  Conductor Components
+|             |  Conductor Components |
 ------|------------------------------
 __Controller__ | The Controller is the View wrapper that will give you all of your lifecycle management features. Think of it as a lighter-weight and more predictable Fragment alternative with an easier to manage lifecycle.
 __Router__ | A Router implements navigation and backstack handling for Controllers. Router objects are attached to Activity/containing ViewGroup pairs. Routers do not directly render or push Views to the container ViewGroup, but instead defer this responsibility to the ControllerChangeHandler specified in a given transaction.
 __ControllerChangeHandler__ | ControllerChangeHandlers are responsible for swapping the View for one Controller to the View of another. They can be useful for performing animations and transitions between Controllers. Several default ControllerChangeHandlers are included.
-__ControllerTransaction__ | Transactions are used to define data about adding Controllers. RouterControllerTransactions are used to push a Controller to a Router with specified ControllerChangeHandlers, while ChildControllerTransactions are used to add child Controllers.
+__RouterTransaction__ | Transactions are used to define data about adding Controllers. RouterTransactions are used to push a Controller to a Router with specified ControllerChangeHandlers, while ChildControllerTransactions are used to add child Controllers.
 
 ## Getting Started
 
@@ -77,7 +77,7 @@ public class MainActivity extends Activity {
 
         setContentView(R.layout.activity_main);
 
-        ViewGroup container = (ViewGroup)findViewById(R.id.controller_container);
+        ViewGroup container = (ViewGroup) findViewById(R.id.controller_container);
 
         router = Conductor.attachRouter(this, container, savedInstanceState);
         if (!router.hasRootController()) {
@@ -103,7 +103,7 @@ public class HomeController extends Controller {
     @Override
     protected View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
         View view = inflater.inflate(R.layout.controller_home, container, false);
-        ((TextView)view.findViewById(R.id.tv_title)).setText("Hello World");
+        ((TextView) view.findViewById(R.id.tv_title)).setText("Hello World");
         return view;
     }
 
@@ -118,7 +118,7 @@ public class HomeController extends Controller {
 
 The lifecycle of a Controller is significantly simpler to understand than that of a Fragment. A lifecycle diagram is shown below:
 
-![Controller Lifecycle](docs/Controller Lifecycle.jpg)
+![Controller Lifecycle](docs/Controller%20Lifecycle.jpg)
 
 ## Advanced Topics
 
@@ -132,7 +132,15 @@ The lifecycle of a Controller is significantly simpler to understand than that o
 `getChildRouter` can be called on a `Controller` in order to get a nested `Router` into which child `Controller`s can be pushed. This enables creating advanced layouts, such as Master/Detail.
 
 ### RxJava Lifecycle
-If the RxLifecycle dependency has been added, there is an `RxController` available that can be used along with the standard [RxLifecycle library](https://github.com/trello/RxLifecycle). There is also a `ControllerLifecycleProvider` available if you do not wish to use this subclass.
+If the AutoDispose dependency has been added, there is a `ControllerScopeProvider` available that can be used along with the standard [AutoDispose library](https://github.com/uber/AutoDispose).
+
+## Community Projects
+The community has provided several helpful modules to make developing apps with Conductor even easier. Here's a collection of helpful libraries:
+
+* [ConductorGlide](https://github.com/MkhytarMkhoian/ConductorGlide) - Adds Glide lifecycle support to Controllers
+* [ConductorDialog](https://github.com/MkhytarMkhoian/ConductorDialog) - Adds a helpful DialogController (a Conductor version of DialogFragment)
+* [Mosby-Conductor](https://github.com/sockeqwe/mosby-conductor) - A plugin to integrate Mosby, an MVP/MVI library
+
 
 ## License
 ```

build.gradle

@@ -1,16 +1,18 @@
 buildscript {
     repositories {
         jcenter()
+        google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.2.3'
+        classpath 'com.android.tools.build:gradle:3.5.2'
     }
 }
 
 allprojects {
     repositories {
-        jcenter()
         mavenCentral()
+        maven { url 'https://maven.google.com' }
+        jcenter()
     }
 }
 

conductor-lint/build.gradle

@@ -8,11 +8,11 @@ configurations {
 }
 
 dependencies {
-    compile rootProject.ext.lintapi
-    compile rootProject.ext.lintchecks
+    implementation rootProject.ext.lintapi
+    implementation rootProject.ext.lintchecks
 
-    testCompile rootProject.ext.lint
-    testCompile rootProject.ext.lintTests
+    testImplementation rootProject.ext.lint
+    testImplementation rootProject.ext.lintTests
 
     lintChecks files(jar)
 }

conductor-lint/src/main/java/com/bluelinelabs/conductor/lint/ControllerChangeHandlerIssueDetector.java

@@ -1,6 +1,7 @@
 package com.bluelinelabs.conductor.lint;
 
 import com.android.tools.lint.client.api.JavaEvaluator;
+import com.android.tools.lint.client.api.UElementHandler;
 import com.android.tools.lint.detector.api.Category;
 import com.android.tools.lint.detector.api.Detector;
 import com.android.tools.lint.detector.api.Implementation;
@@ -8,13 +9,16 @@ import com.android.tools.lint.detector.api.Issue;
 import com.android.tools.lint.detector.api.JavaContext;
 import com.android.tools.lint.detector.api.Scope;
 import com.android.tools.lint.detector.api.Severity;
-import com.intellij.psi.PsiClass;
-import com.intellij.psi.PsiMethod;
+
+import org.jetbrains.uast.UClass;
+import org.jetbrains.uast.UElement;
+import org.jetbrains.uast.UMethod;
+import org.jetbrains.uast.UTypeReferenceExpression;
 
 import java.util.Collections;
 import java.util.List;
 
-public final class ControllerChangeHandlerIssueDetector extends Detector implements Detector.JavaPsiScanner {
+public final class ControllerChangeHandlerIssueDetector extends Detector implements Detector.UastScanner {
 
     public static final Issue ISSUE =
             Issue.create("ValidControllerChangeHandler", "ControllerChangeHandler not instantiatable",
@@ -23,47 +27,67 @@ public final class ControllerChangeHandlerIssueDetector extends Detector impleme
                     Category.CORRECTNESS, 6, Severity.FATAL,
                     new Implementation(ControllerChangeHandlerIssueDetector.class, Scope.JAVA_FILE_SCOPE));
 
-    public ControllerChangeHandlerIssueDetector() { }
+    private static final String CLASS_NAME = "com.bluelinelabs.conductor.ControllerChangeHandler";
 
     @Override
-    public List<String> applicableSuperClasses() {
-        return Collections.singletonList("com.bluelinelabs.conductor.ControllerChangeHandler");
+    public List<Class<? extends UElement>> getApplicableUastTypes() {
+        return Collections.<Class<? extends UElement>>singletonList(UClass.class);
     }
 
     @Override
-    public void checkClass(JavaContext context, PsiClass declaration) {
+    public UElementHandler createUastHandler(final JavaContext context) {
         final JavaEvaluator evaluator = context.getEvaluator();
-        if (evaluator.isAbstract(declaration)) {
-            return;
-        }
 
-        if (!evaluator.isPublic(declaration)) {
-            String message = String.format("This ControllerChangeHandler class should be public (%1$s)", declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-            return;
-        }
+        return new UElementHandler() {
 
-        if (declaration.getContainingClass() != null && !evaluator.isStatic(declaration)) {
-            String message = String.format("This ControllerChangeHandler inner class should be static (%1$s)", declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-            return;
-        }
+            @Override
+            public void visitClass(UClass node) {
+                if (evaluator.isAbstract(node)) {
+                    return;
+                }
 
-        boolean hasDefaultConstructor = false;
-        PsiMethod[] constructors = declaration.getConstructors();
-        for (PsiMethod constructor : constructors) {
-            if (evaluator.isPublic(constructor)) {
-                if (constructor.getParameterList().getParametersCount() == 0) {
-                    hasDefaultConstructor = true;
-                    break;
+                boolean hasSuperType = false;
+                for (UTypeReferenceExpression superType : node.getUastSuperTypes()) {
+                    if (CLASS_NAME.equals(superType.asRenderString())) {
+                        hasSuperType = true;
+                        break;
+                    }
+                }
+                if (!hasSuperType) {
+                    return;
+                }
+
+                if (!evaluator.isPublic(node)) {
+                    String message = String.format("This ControllerChangeHandler class should be public (%1$s)", node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
+                    return;
+                }
+
+                if (node.getContainingClass() != null && !evaluator.isStatic(node)) {
+                    String message = String.format("This ControllerChangeHandler inner class should be static (%1$s)", node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
+                    return;
+                }
+
+                boolean hasConstructor = false;
+                boolean hasDefaultConstructor = false;
+                for (UMethod method : node.getMethods()) {
+                    if (method.isConstructor()) {
+                        hasConstructor = true;
+                        if (evaluator.isPublic(method) && method.getUastParameters().size() == 0) {
+                            hasDefaultConstructor = true;
+                            break;
+                        }
+                    }
+                }
+
+                if (hasConstructor && !hasDefaultConstructor) {
+                    String message = String.format(
+                            "This ControllerChangeHandler needs to have a public default constructor (`%1$s`)", node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
                 }
             }
-        }
-
-        if (constructors.length > 0 && !hasDefaultConstructor) {
-            String message = String.format(
-                    "This ControllerChangeHandler needs to have a public default constructor (`%1$s`)", declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-        }
+        };
     }
-}
+
+}

conductor-lint/src/main/java/com/bluelinelabs/conductor/lint/ControllerIssueDetector.java

@@ -2,6 +2,7 @@ package com.bluelinelabs.conductor.lint;
 
 import com.android.SdkConstants;
 import com.android.tools.lint.client.api.JavaEvaluator;
+import com.android.tools.lint.client.api.UElementHandler;
 import com.android.tools.lint.detector.api.Category;
 import com.android.tools.lint.detector.api.Detector;
 import com.android.tools.lint.detector.api.Implementation;
@@ -9,14 +10,17 @@ import com.android.tools.lint.detector.api.Issue;
 import com.android.tools.lint.detector.api.JavaContext;
 import com.android.tools.lint.detector.api.Scope;
 import com.android.tools.lint.detector.api.Severity;
-import com.intellij.psi.PsiClass;
-import com.intellij.psi.PsiMethod;
-import com.intellij.psi.PsiParameter;
+
+import org.jetbrains.uast.UClass;
+import org.jetbrains.uast.UElement;
+import org.jetbrains.uast.UMethod;
+import org.jetbrains.uast.UParameter;
+import org.jetbrains.uast.UTypeReferenceExpression;
 
 import java.util.Collections;
 import java.util.List;
 
-public final class ControllerIssueDetector extends Detector implements Detector.JavaPsiScanner {
+public final class ControllerIssueDetector extends Detector implements Detector.UastScanner {
 
     public static final Issue ISSUE =
             Issue.create("ValidController", "Controller not instantiatable",
@@ -25,58 +29,76 @@ public final class ControllerIssueDetector extends Detector implements Detector.
                             + " case of the process being killed.", Category.CORRECTNESS, 6, Severity.FATAL,
                     new Implementation(ControllerIssueDetector.class, Scope.JAVA_FILE_SCOPE));
 
-    public ControllerIssueDetector() { }
+    private static final String CLASS_NAME = "com.bluelinelabs.conductor.Controller";
 
     @Override
-    public List<String> applicableSuperClasses() {
-        return Collections.singletonList("com.bluelinelabs.conductor.Controller");
+    public List<Class<? extends UElement>> getApplicableUastTypes() {
+        return Collections.<Class<? extends UElement>>singletonList(UClass.class);
     }
 
     @Override
-    public void checkClass(JavaContext context, PsiClass declaration) {
+    public UElementHandler createUastHandler(final JavaContext context) {
         final JavaEvaluator evaluator = context.getEvaluator();
-        if (evaluator.isAbstract(declaration)) {
-            return;
-        }
 
-        if (!evaluator.isPublic(declaration)) {
-            String message = String.format("This Controller class should be public (%1$s)", declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-            return;
-        }
+        return new UElementHandler() {
+            @Override
+            public void visitClass(UClass node) {
+                if (evaluator.isAbstract(node)) {
+                    return;
+                }
 
-        if (declaration.getContainingClass() != null && !evaluator.isStatic(declaration)) {
-            String message = String.format("This Controller inner class should be static (%1$s)", declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-            return;
-        }
+                boolean hasSuperType = false;
+                for (UTypeReferenceExpression superType : node.getUastSuperTypes()) {
+                    if (CLASS_NAME.equals(superType.asRenderString())) {
+                        hasSuperType = true;
+                        break;
+                    }
+                }
+                if (!hasSuperType) {
+                    return;
+                }
 
+                if (!evaluator.isPublic(node)) {
+                    String message = String.format("This Controller class should be public (%1$s)", node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
+                    return;
+                }
 
-        boolean hasDefaultConstructor = false;
-        boolean hasBundleConstructor = false;
-        PsiMethod[] constructors = declaration.getConstructors();
-        for (PsiMethod constructor : constructors) {
-            if (evaluator.isPublic(constructor)) {
-                PsiParameter[] parameters = constructor.getParameterList().getParameters();
+                if (node.getContainingClass() != null && !evaluator.isStatic(node)) {
+                    String message = String.format("This Controller inner class should be static (%1$s)", node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
+                    return;
+                }
 
-                if (parameters.length == 0) {
-                    hasDefaultConstructor = true;
-                    break;
-                } else if (parameters.length == 1 &&
-                        parameters[0].getType().equalsToText(SdkConstants.CLASS_BUNDLE) ||
-                        parameters[0].getType().equalsToText("Bundle")) {
-                    hasBundleConstructor = true;
-                    break;
+                boolean hasConstructor = false;
+                boolean hasDefaultConstructor = false;
+                boolean hasBundleConstructor = false;
+                for (UMethod method : node.getMethods()) {
+                    if (method.isConstructor()) {
+                        hasConstructor = true;
+                        if (evaluator.isPublic(method)) {
+                            List<UParameter> parameters = method.getUastParameters();
+                            if (parameters.size() == 0) {
+                                hasDefaultConstructor = true;
+                                break;
+                            } else if (parameters.size() == 1 &&
+                                    (parameters.get(0).getType().equalsToText(SdkConstants.CLASS_BUNDLE)) ||
+                                    parameters.get(0).getType().equalsToText("Bundle")) {
+                                hasBundleConstructor = true;
+                            }
+                        }
+                    }
+                }
+
+                if (hasConstructor && !hasDefaultConstructor && !hasBundleConstructor) {
+                    String message = String.format(
+                            "This Controller needs to have either a public default constructor or a" +
+                                    " public single-argument constructor that takes a Bundle. (`%1$s`)",
+                            node.getQualifiedName());
+                    context.report(ISSUE, node, context.getLocation((UElement) node), message);
                 }
             }
-        }
-
-        if (constructors.length > 0 && !hasDefaultConstructor && !hasBundleConstructor) {
-            String message = String.format(
-                    "This Controller needs to have either a public default constructor or a" +
-                            " public single-argument constructor that takes a Bundle. (`%1$s`)",
-                    declaration.getQualifiedName());
-            context.report(ISSUE, declaration, context.getLocation(declaration), message);
-        }
+        };
     }
-}
+    
+}

conductor-lint/src/main/java/com/bluelinelabs/conductor/lint/IssueRegistry.java

@@ -5,10 +5,19 @@ import com.android.tools.lint.detector.api.Issue;
 import java.util.Arrays;
 import java.util.List;
 
+import static com.android.tools.lint.detector.api.ApiKt.CURRENT_API;
+
 public final class IssueRegistry extends com.android.tools.lint.client.api.IssueRegistry {
-    @Override public List<Issue> getIssues() {
+
+    @Override
+    public List<Issue> getIssues() {
         return Arrays.asList(
                 ControllerIssueDetector.ISSUE,
                 ControllerChangeHandlerIssueDetector.ISSUE);
     }
-}
+
+    @Override
+    public int getApi() {
+        return CURRENT_API;
+    }
+}

conductor-lint/src/test/java/com/bluelinelabs/conductor/lint/ControllerChangeHandlerDetectorTest.java

@@ -1,19 +1,13 @@
 package com.bluelinelabs.conductor.lint;
 
-import com.android.tools.lint.checks.infrastructure.LintDetectorTest;
-import com.android.tools.lint.detector.api.Detector;
-import com.android.tools.lint.detector.api.Issue;
-
 import org.intellij.lang.annotations.Language;
+import org.junit.Test;
 
-import java.util.Collections;
-import java.util.List;
+import static com.android.tools.lint.checks.infrastructure.TestFiles.java;
+import static com.android.tools.lint.checks.infrastructure.TestLintTask.lint;
 
-import static com.google.common.truth.Truth.assertThat;
+public class ControllerChangeHandlerDetectorTest {
 
-public class ControllerChangeHandlerDetectorTest extends LintDetectorTest {
-
-    private static final String NO_WARNINGS = "No warnings.";
     private static final String CONSTRUCTOR =
             "src/test/SampleHandler.java:2: Error: This ControllerChangeHandler needs to have a public default constructor (test.SampleHandler) [ValidControllerChangeHandler]\n"
             + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
@@ -25,72 +19,94 @@ public class ControllerChangeHandlerDetectorTest extends LintDetectorTest {
                     + "^\n"
                     + "1 errors, 0 warnings\n";
 
-    public void testWithNoConstructor() throws Exception {
+    @Test
+    public void testWithNoConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithEmptyConstructor() throws Exception {
+    @Test
+    public void testWithEmptyConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "    public SampleHandler() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithInvalidConstructor() throws Exception {
+    @Test
+    public void testWithInvalidConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "    public SampleHandler(int number) { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(CONSTRUCTOR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(CONSTRUCTOR);
     }
 
-    public void testWithEmptyAndInvalidConstructor() throws Exception {
+    @Test
+    public void testWithEmptyAndInvalidConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "    public SampleHandler() { }\n"
                 + "    public SampleHandler(int number) { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithPrivateConstructor() throws Exception {
+    @Test
+    public void testWithPrivateConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "    private SampleHandler() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(CONSTRUCTOR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(CONSTRUCTOR);
     }
 
-    public void testWithPrivateClass() throws Exception {
+    @Test
+    public void testWithPrivateClass() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "private class SampleHandler extends com.bluelinelabs.conductor.ControllerChangeHandler {\n"
                 + "    public SampleHandler() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(PRIVATE_CLASS_ERROR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(PRIVATE_CLASS_ERROR);
     }
 
-    @Override
-    protected Detector getDetector() {
-        return new ControllerChangeHandlerIssueDetector();
-    }
-
-    @Override
-    protected List<Issue> getIssues() {
-        return Collections.singletonList(ControllerChangeHandlerIssueDetector.ISSUE);
-    }
-
-    @Override
-    protected boolean allowCompilationErrors() {
-        return true;
-    }
 }

conductor-lint/src/test/java/com/bluelinelabs/conductor/lint/ControllerDetectorTest.java

@@ -1,19 +1,13 @@
 package com.bluelinelabs.conductor.lint;
 
-import com.android.tools.lint.checks.infrastructure.LintDetectorTest;
-import com.android.tools.lint.detector.api.Detector;
-import com.android.tools.lint.detector.api.Issue;
-
 import org.intellij.lang.annotations.Language;
+import org.junit.Test;
 
-import java.util.Collections;
-import java.util.List;
+import static com.android.tools.lint.checks.infrastructure.TestFiles.java;
+import static com.android.tools.lint.checks.infrastructure.TestLintTask.lint;
 
-import static com.google.common.truth.Truth.assertThat;
+public class ControllerDetectorTest {
 
-public class ControllerDetectorTest extends LintDetectorTest {
-
-    private static final String NO_WARNINGS = "No warnings.";
     private static final String CONSTRUCTOR_ERROR =
             "src/test/SampleController.java:2: Error: This Controller needs to have either a public default constructor or a public single-argument constructor that takes a Bundle. (test.SampleController) [ValidController]\n"
             + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
@@ -25,72 +19,94 @@ public class ControllerDetectorTest extends LintDetectorTest {
                     + "^\n"
                     + "1 errors, 0 warnings\n";
 
-    public void testWithNoConstructor() throws Exception {
+    @Test
+    public void testWithNoConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithEmptyConstructor() throws Exception {
+    @Test
+    public void testWithEmptyConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "    public SampleController() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithInvalidConstructor() throws Exception {
+    @Test
+    public void testWithInvalidConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "    public SampleController(int number) { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(CONSTRUCTOR_ERROR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(CONSTRUCTOR_ERROR);
     }
 
-    public void testWithEmptyAndInvalidConstructor() throws Exception {
+    @Test
+    public void testWithEmptyAndInvalidConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "    public SampleController() { }\n"
                 + "    public SampleController(int number) { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(NO_WARNINGS);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expectClean();
     }
 
-    public void testWithPrivateConstructor() throws Exception {
+    @Test
+    public void testWithPrivateConstructor() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "public class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "    private SampleController() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(CONSTRUCTOR_ERROR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(CONSTRUCTOR_ERROR);
     }
 
-    public void testWithPrivateClass() throws Exception {
+    @Test
+    public void testWithPrivateClass() {
         @Language("JAVA") String source = ""
                 + "package test;\n"
                 + "private class SampleController extends com.bluelinelabs.conductor.Controller {\n"
                 + "    public SampleController() { }\n"
                 + "}";
-        assertThat(lintProject(java(source))).isEqualTo(CLASS_ERROR);
+
+        lint()
+                .files(java(source))
+                .issues(ControllerIssueDetector.ISSUE, ControllerChangeHandlerIssueDetector.ISSUE)
+                .run()
+                .expect(CLASS_ERROR);
     }
 
-    @Override
-    protected Detector getDetector() {
-        return new ControllerIssueDetector();
-    }
-
-    @Override
-    protected List<Issue> getIssues() {
-        return Collections.singletonList(ControllerIssueDetector.ISSUE);
-    }
-
-    @Override
-    protected boolean allowCompilationErrors() {
-        return true;
-    }
 }

conductor-modules/androidx-transition/build.gradle

@@ -0,0 +1,35 @@
+buildscript {
+    repositories {
+        jcenter()
+    }
+}
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
+
+    defaultConfig {
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
+        versionCode Integer.parseInt(project.VERSION_CODE)
+        versionName project.VERSION_NAME
+    }
+}
+
+dependencies {
+    implementation rootProject.ext.androidxAppCompat
+    implementation rootProject.ext.androidxCollection
+    api rootProject.ext.androidxTransition
+    implementation project(':conductor')
+}
+
+ext.artifactId = 'conductor-androidx-transition'
+
+apply from: rootProject.file('dependencies.gradle')
+apply from: rootProject.file('gradle-mvn-push.gradle')

conductor-modules/androidx-transition/gradle.properties

@@ -0,0 +1,3 @@
+POM_NAME=Conductor AndroidX Transition Extensions
+POM_ARTIFACT_ID=conductor-androidx-transition
+POM_PACKAGING=aar

conductor-modules/androidx-transition/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest package="com.bluelinelabs.conductor.androidxtransition">
+    <application />
+</manifest>

conductor-modules/androidx-transition/src/main/java/com/bluelinelabs/conductor/changehandler/androidxtransition/SharedElementTransitionChangeHandler.java

@@ -0,0 +1,653 @@
+package com.bluelinelabs.conductor.changehandler.androidxtransition;
+
+import android.graphics.Rect;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.ViewTreeObserver;
+import android.view.ViewTreeObserver.OnPreDrawListener;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.collection.ArrayMap;
+import androidx.core.app.SharedElementCallback;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.ViewGroupCompat;
+import androidx.transition.Transition;
+import androidx.transition.TransitionSet;
+
+import com.bluelinelabs.conductor.Controller;
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+import com.bluelinelabs.conductor.internal.TransitionUtils;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A TransitionChangeHandler that facilitates using different Transitions for the entering view, the exiting view,
+ * and shared elements between the two.
+ */
+// Much of this class is based on FragmentTransition.java and FragmentTransitionCompat21.java from the Android support library
+public abstract class SharedElementTransitionChangeHandler extends TransitionChangeHandler {
+
+    // A map of from -> to names. Generally these will be the same.
+    @NonNull  final ArrayMap<String, String> sharedElementNames = new ArrayMap<>();
+
+    @NonNull  final List<String> waitForTransitionNames = new ArrayList<>();
+    @NonNull  final List<ViewParentPair> removedViews = new ArrayList<>();
+
+    @Nullable Transition exitTransition;
+    @Nullable Transition enterTransition;
+    @Nullable Transition sharedElementTransition;
+    @Nullable private SharedElementCallback exitTransitionCallback;
+    @Nullable private SharedElementCallback enterTransitionCallback;
+
+    @NonNull
+    @Override
+    protected final Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        exitTransition = getExitTransition(container, from, to, isPush);
+        enterTransition = getEnterTransition(container, from, to, isPush);
+        sharedElementTransition = getSharedElementTransition(container, from, to, isPush);
+        exitTransitionCallback = getExitTransitionCallback(container, from, to, isPush);
+        enterTransitionCallback = getEnterTransitionCallback(container, from, to, isPush);
+
+        if (enterTransition == null && sharedElementTransition == null && exitTransition == null) {
+            throw new IllegalStateException("SharedElementTransitionChangeHandler must have at least one transaction.");
+        }
+
+        return mergeTransitions(isPush);
+    }
+
+    @Override
+    public void prepareForTransition(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, @NonNull final Transition transition, final boolean isPush, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        OnTransitionPreparedListener listener = new OnTransitionPreparedListener() {
+            @Override
+            public void onPrepared() {
+                configureTransition(container, from, to, transition, isPush);
+                onTransitionPreparedListener.onPrepared();
+            }
+        };
+
+        configureSharedElements(container, from, to, isPush);
+
+        if (to != null && to.getParent() == null && waitForTransitionNames.size() > 0) {
+            waitOnAllTransitionNames(to, listener);
+            container.addView(to);
+        } else {
+            listener.onPrepared();
+        }
+    }
+
+    @Override
+    public final void executePropertyChanges(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @Nullable Transition transition, boolean isPush) {
+        if (to != null && removedViews.size() > 0) {
+            to.setVisibility(View.VISIBLE);
+
+            for (ViewParentPair removedView : removedViews) {
+                removedView.parent.addView(removedView.view);
+            }
+
+            removedViews.clear();
+        }
+
+        super.executePropertyChanges(container, from, to, transition, isPush);
+    }
+
+    @Override
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
+        super.onAbortPush(newHandler, newTop);
+
+        removedViews.clear();
+    }
+
+    void configureTransition(@NonNull final ViewGroup container, @Nullable View from, @Nullable View to, @NonNull final Transition transition, boolean isPush) {
+        final View nonExistentView = new View(container.getContext());
+
+        List<View> fromSharedElements = new ArrayList<>();
+        List<View> toSharedElements = new ArrayList<>();
+
+        configureSharedElements(container, nonExistentView, to, from, isPush, fromSharedElements, toSharedElements);
+
+        List<View> exitingViews = exitTransition != null ? configureEnteringExitingViews(exitTransition, from, fromSharedElements, nonExistentView) : null;
+        if (exitingViews == null || exitingViews.isEmpty()) {
+            exitTransition = null;
+        }
+
+        if (enterTransition != null) {
+            enterTransition.addTarget(nonExistentView);
+        }
+
+        final List<View> enteringViews = new ArrayList<>();
+        scheduleRemoveTargets(transition, enterTransition, enteringViews, exitTransition, exitingViews, sharedElementTransition, toSharedElements);
+        scheduleTargetChange(container, to, nonExistentView, toSharedElements, enteringViews, exitingViews);
+
+        setNameOverrides(container, toSharedElements);
+        scheduleNameReset(container, toSharedElements);
+    }
+
+    private void waitOnAllTransitionNames(@NonNull final View to, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        OnPreDrawListener onPreDrawListener = new OnPreDrawListener() {
+            boolean addedSubviewListeners;
+
+            @Override
+            public boolean onPreDraw() {
+                List<View> foundViews = new ArrayList<>();
+                boolean allViewsFound = true;
+                for (String transitionName : waitForTransitionNames) {
+                    View namedView = TransitionUtils.findNamedView(to, transitionName);
+                    if (namedView != null) {
+                        foundViews.add(TransitionUtils.findNamedView(to, transitionName));
+                    } else {
+                        allViewsFound = false;
+                        break;
+                    }
+                }
+
+                if (allViewsFound && !addedSubviewListeners) {
+                    addedSubviewListeners = true;
+                    waitOnChildTransitionNames(to, foundViews, this, onTransitionPreparedListener);
+                }
+
+                return false;
+            }
+        };
+
+        to.getViewTreeObserver().addOnPreDrawListener(onPreDrawListener);
+    }
+
+    void waitOnChildTransitionNames(@NonNull final View to, @NonNull List<View> foundViews, @NonNull final OnPreDrawListener parentPreDrawListener, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        for (final View view : foundViews) {
+            OneShotPreDrawListener.add(true, view, new Runnable() {
+                @Override
+                public void run() {
+                    waitForTransitionNames.remove(ViewCompat.getTransitionName(view));
+
+                    removedViews.add(new ViewParentPair(view, (ViewGroup)view.getParent()));
+                    ((ViewGroup)view.getParent()).removeView(view);
+
+                    if (waitForTransitionNames.size() == 0) {
+                        to.getViewTreeObserver().removeOnPreDrawListener(parentPreDrawListener);
+                        to.setVisibility(View.INVISIBLE);
+                        onTransitionPreparedListener.onPrepared();
+                    }
+                }
+            });
+        }
+    }
+
+    private void scheduleTargetChange(@NonNull final ViewGroup container, @Nullable final View to, @NonNull final View nonExistentView,
+                                      @NonNull final List<View> toSharedElements, @NonNull final List<View> enteringViews, @Nullable final List<View> exitingViews) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                if (enterTransition != null) {
+                    enterTransition.removeTarget(nonExistentView);
+                    List<View> views = configureEnteringExitingViews(enterTransition, to, toSharedElements, nonExistentView);
+                    enteringViews.addAll(views);
+                }
+
+                if (exitingViews != null) {
+                    if (exitTransition != null) {
+                        List<View> tempExiting = new ArrayList<>();
+                        tempExiting.add(nonExistentView);
+                        TransitionUtils.replaceTargets(exitTransition, exitingViews, tempExiting);
+                    }
+                    exitingViews.clear();
+                    exitingViews.add(nonExistentView);
+                }
+            }
+        });
+    }
+
+    private Transition mergeTransitions(boolean isPush) {
+        boolean overlap = enterTransition == null || exitTransition == null || allowTransitionOverlap(isPush);
+
+        if (overlap) {
+            return TransitionUtils.mergeTransitions(TransitionSet.ORDERING_TOGETHER, exitTransition, enterTransition, sharedElementTransition);
+        } else {
+            Transition staggered = TransitionUtils.mergeTransitions(TransitionSet.ORDERING_SEQUENTIAL, exitTransition, enterTransition);
+            return TransitionUtils.mergeTransitions(TransitionSet.ORDERING_TOGETHER, staggered, sharedElementTransition);
+        }
+    }
+
+    @NonNull List<View> configureEnteringExitingViews(@NonNull Transition transition, @Nullable View view, @NonNull List<View> sharedElements, @NonNull View nonExistentView) {
+        List<View> viewList = new ArrayList<>();
+        if (view != null) {
+            captureTransitioningViews(viewList, view);
+        }
+        viewList.removeAll(sharedElements);
+        if (!viewList.isEmpty()) {
+            viewList.add(nonExistentView);
+            TransitionUtils.addTargets(transition, viewList);
+        }
+        return viewList;
+    }
+
+    private void configureSharedElements(@NonNull ViewGroup container, @NonNull final View nonExistentView, @Nullable final View to, @Nullable View from,
+                                         final boolean isPush, @NonNull final List<View> fromSharedElements, @NonNull final List<View> toSharedElements) {
+
+        if (to == null || from == null) {
+            return;
+        }
+
+        ArrayMap<String, View> capturedFromSharedElements = captureFromSharedElements(from);
+
+        if (sharedElementNames.isEmpty()) {
+            sharedElementTransition = null;
+        } else if (capturedFromSharedElements != null) {
+            fromSharedElements.addAll(capturedFromSharedElements.values());
+        }
+
+        if (enterTransition == null && exitTransition == null && sharedElementTransition == null) {
+            return;
+        }
+
+        callSharedElementStartEnd(capturedFromSharedElements, true);
+
+        final Rect toEpicenter;
+        if (sharedElementTransition != null) {
+            toEpicenter = new Rect();
+            TransitionUtils.setTargets(sharedElementTransition, nonExistentView, fromSharedElements);
+            setFromEpicenter(capturedFromSharedElements);
+            if (enterTransition != null) {
+                enterTransition.setEpicenterCallback(new Transition.EpicenterCallback() {
+                    @Override
+                    public Rect onGetEpicenter(Transition transition) {
+                        if (toEpicenter.isEmpty()) {
+                            return null;
+                        }
+                        return toEpicenter;
+                    }
+                });
+            }
+        } else {
+            toEpicenter = null;
+        }
+
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                ArrayMap<String, View> capturedToSharedElements = captureToSharedElements(to, isPush);
+
+                if (capturedToSharedElements != null) {
+                    toSharedElements.addAll(capturedToSharedElements.values());
+                    toSharedElements.add(nonExistentView);
+                }
+
+                callSharedElementStartEnd(capturedToSharedElements, false);
+                if (sharedElementTransition != null) {
+                    sharedElementTransition.getTargets().clear();
+                    sharedElementTransition.getTargets().addAll(toSharedElements);
+                    TransitionUtils.replaceTargets(sharedElementTransition, fromSharedElements, toSharedElements);
+
+                    final View toEpicenterView = getToEpicenterView(capturedToSharedElements);
+                    if (toEpicenterView != null && toEpicenter != null) {
+                        TransitionUtils.getBoundsOnScreen(toEpicenterView, toEpicenter);
+                    }
+                }
+            }
+        });
+    }
+
+    @Nullable View getToEpicenterView(@Nullable ArrayMap<String, View> toSharedElements) {
+        if (enterTransition != null && sharedElementNames.size() > 0 && toSharedElements != null) {
+            return toSharedElements.get(sharedElementNames.valueAt(0));
+        }
+        return null;
+    }
+
+    private void setFromEpicenter(@Nullable ArrayMap<String, View> fromSharedElements) {
+        if (sharedElementNames.size() > 0 && fromSharedElements != null) {
+            final View fromEpicenterView = fromSharedElements.get(sharedElementNames.keyAt(0));
+
+            if (sharedElementTransition != null) {
+                TransitionUtils.setEpicenter(sharedElementTransition, fromEpicenterView);
+            }
+
+            if (exitTransition != null) {
+                TransitionUtils.setEpicenter(exitTransition, fromEpicenterView);
+            }
+        }
+    }
+
+    @Nullable ArrayMap<String, View> captureToSharedElements(@Nullable final View to, boolean isPush) {
+        if (sharedElementNames.isEmpty() || sharedElementTransition == null || to == null) {
+            sharedElementNames.clear();
+            return null;
+        }
+
+        final ArrayMap<String, View> toSharedElements = new ArrayMap<>();
+        TransitionUtils.findNamedViews(toSharedElements, to);
+        for (ViewParentPair removedView : removedViews) {
+            toSharedElements.put(ViewCompat.getTransitionName(removedView.view), removedView.view);
+        }
+
+        final List<String> names = new ArrayList<>(sharedElementNames.values());
+
+        toSharedElements.retainAll(names);
+        if (enterTransitionCallback != null) {
+            enterTransitionCallback.onMapSharedElements(names, toSharedElements);
+            for (int i = names.size() - 1; i >= 0; i--) {
+                String name = names.get(i);
+                View view = toSharedElements.get(name);
+                if (view == null) {
+                    String key = findKeyForValue(sharedElementNames, name);
+                    if (key != null) {
+                        sharedElementNames.remove(key);
+                    }
+                } else if (!name.equals(ViewCompat.getTransitionName(view))) {
+                    String key = findKeyForValue(sharedElementNames, name);
+                    if (key != null) {
+                        sharedElementNames.put(key, ViewCompat.getTransitionName(view));
+                    }
+                }
+            }
+        } else {
+            for (int i = sharedElementNames.size() - 1; i >= 0; i--) {
+                final String targetName = sharedElementNames.valueAt(i);
+                if (!toSharedElements.containsKey(targetName)) {
+                    sharedElementNames.removeAt(i);
+                }
+            }
+        }
+        return toSharedElements;
+    }
+
+    @Nullable String findKeyForValue(@NonNull ArrayMap<String, String> map, @NonNull String value) {
+        final int numElements = map.size();
+        for (int i = 0; i < numElements; i++) {
+            if (value.equals(map.valueAt(i))) {
+                return map.keyAt(i);
+            }
+        }
+        return null;
+    }
+
+    @Nullable
+    private ArrayMap<String, View> captureFromSharedElements(@NonNull View from) {
+        if (sharedElementNames.isEmpty() || sharedElementTransition == null) {
+            sharedElementNames.clear();
+            return null;
+        }
+
+        final ArrayMap<String, View> fromSharedElements = new ArrayMap<>();
+        TransitionUtils.findNamedViews(fromSharedElements, from);
+
+        final List<String> names = new ArrayList<>(sharedElementNames.keySet());
+
+        fromSharedElements.retainAll(names);
+        if (exitTransitionCallback != null) {
+            exitTransitionCallback.onMapSharedElements(names, fromSharedElements);
+            for (int i = names.size() - 1; i >= 0; i--) {
+                String name = names.get(i);
+                View view = fromSharedElements.get(name);
+                if (view == null) {
+                    sharedElementNames.remove(name);
+                } else if (!name.equals(ViewCompat.getTransitionName(view))) {
+                    String targetValue = sharedElementNames.remove(name);
+                    sharedElementNames.put(ViewCompat.getTransitionName(view), targetValue);
+                }
+            }
+        } else {
+            sharedElementNames.retainAll(fromSharedElements.keySet());
+        }
+        return fromSharedElements;
+    }
+
+    void callSharedElementStartEnd(@Nullable ArrayMap<String, View> sharedElements, boolean isStart) {
+        if (enterTransitionCallback != null) {
+            final int count = sharedElements == null ? 0 : sharedElements.size();
+            List<View> views = new ArrayList<>(count);
+            List<String> names = new ArrayList<>(count);
+            for (int i = 0; i < count; i++) {
+                names.add(sharedElements.keyAt(i));
+                views.add(sharedElements.valueAt(i));
+            }
+            if (isStart) {
+                enterTransitionCallback.onSharedElementStart(names, views, null);
+            } else {
+                enterTransitionCallback.onSharedElementEnd(names, views, null);
+            }
+        }
+    }
+
+    private void captureTransitioningViews(@NonNull List<View> transitioningViews, @NonNull View view) {
+        if (view.getVisibility() == View.VISIBLE) {
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                if (ViewGroupCompat.isTransitionGroup(viewGroup)) {
+                    transitioningViews.add(viewGroup);
+                } else {
+                    int count = viewGroup.getChildCount();
+                    for (int i = 0; i < count; i++) {
+                        View child = viewGroup.getChildAt(i);
+                        captureTransitioningViews(transitioningViews, child);
+                    }
+                }
+            } else {
+                transitioningViews.add(view);
+            }
+        }
+    }
+
+    private void scheduleRemoveTargets(@NonNull final Transition overallTransition,
+                                       @Nullable final Transition enterTransition, @Nullable final List<View> enteringViews,
+                                       @Nullable final Transition exitTransition, @Nullable final List<View> exitingViews,
+                                       @Nullable final Transition sharedElementTransition, @Nullable final List<View> toSharedElements) {
+        overallTransition.addListener(new Transition.TransitionListener() {
+            @Override
+            public void onTransitionStart(Transition transition) {
+                if (enterTransition != null && enteringViews != null) {
+                    TransitionUtils.replaceTargets(enterTransition, enteringViews, null);
+                }
+                if (exitTransition != null && exitingViews != null) {
+                    TransitionUtils.replaceTargets(exitTransition, exitingViews, null);
+                }
+                if (sharedElementTransition != null && toSharedElements != null) {
+                    TransitionUtils.replaceTargets(sharedElementTransition, toSharedElements, null);
+                }
+            }
+
+            @Override
+            public void onTransitionEnd(Transition transition) { }
+
+            @Override
+            public void onTransitionCancel(Transition transition) { }
+
+            @Override
+            public void onTransitionPause(Transition transition) { }
+
+            @Override
+            public void onTransitionResume(Transition transition) { }
+        });
+    }
+
+    private void setNameOverrides(@NonNull final View container, @NonNull final List<View> toSharedElements) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                final int numSharedElements = toSharedElements.size();
+                for (int i = 0; i < numSharedElements; i++) {
+                    View view = toSharedElements.get(i);
+                    String name = ViewCompat.getTransitionName(view);
+                    if (name != null) {
+                        String inName = findKeyForValue(sharedElementNames, name);
+                        ViewCompat.setTransitionName(view, inName);
+                    }
+                }
+            }
+        });
+    }
+
+    private void scheduleNameReset(@NonNull final ViewGroup container, @NonNull final List<View> toSharedElements) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                final int numSharedElements = toSharedElements.size();
+                for (int i = 0; i < numSharedElements; i++) {
+                    final View view = toSharedElements.get(i);
+                    final String name = ViewCompat.getTransitionName(view);
+                    final String inName = sharedElementNames.get(name);
+                    ViewCompat.setTransitionName(view, inName);
+                }
+            }
+        });
+    }
+
+    /**
+     * Will be called when views are ready to have their shared elements configured. Within this method one of the addSharedElement methods
+     * should be called for each shared element that will be used. If one or more of these shared elements will not instantly be available in
+     * the incoming view (for ex, in a RecyclerView), waitOnSharedElementNamed can be called to delay the transition until everything is available.
+     */
+    public abstract void configureSharedElements(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on the exiting ("from") view, if one is desired.
+     */
+    @Nullable
+    public abstract Transition getExitTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on shared elements between the from and to views.
+     */
+    @Nullable
+    public abstract Transition getSharedElementTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on the entering ("to") view, if one is desired.
+     */
+    @Nullable
+    public abstract Transition getEnterTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return a callback that can be used to customize transition behavior of the shared element transition for the "from" view.
+     */
+    @Nullable
+    public SharedElementCallback getExitTransitionCallback(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        return null;
+    }
+
+    /**
+     * Should return a callback that can be used to customize transition behavior of the shared element transition for the "to" view.
+     */
+    @Nullable
+    public SharedElementCallback getEnterTransitionCallback(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        return null;
+    }
+
+    /**
+     * Should return whether or not the the exit transition and enter transition should overlap. If true,
+     * the enter transition will start as soon as possible. Otherwise, the enter transition will wait until the
+     * completion of the exit transition. Defaults to true.
+     */
+    public boolean allowTransitionOverlap(boolean isPush) {
+        return true;
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition.
+     *
+     * @param name The transition name that is used for both the entering and exiting views.
+     */
+    protected final void addSharedElement(@NonNull String name) {
+        sharedElementNames.put(name, name);
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition. Maps the name used in the
+     * "from" view to the name used in the "to" view if they are not the same.
+     *
+     * @param fromName The transition name used in the "from" view
+     * @param toName The transition name used in the "to" view
+     */
+    protected final void addSharedElement(@NonNull String fromName, @NonNull String toName) {
+        sharedElementNames.put(fromName, toName);
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition. Maps the name used in the
+     * "from" view to the name used in the "to" view if they are not the same.
+     *
+     * @param sharedElement The view from the "from" view that will take part in the shared element transition
+     * @param toName The transition name used in the "to" view
+     */
+    protected final void addSharedElement(@NonNull View sharedElement, @NonNull String toName) {
+        String transitionName = ViewCompat.getTransitionName(sharedElement);
+        if (transitionName == null) {
+            throw new IllegalArgumentException("Unique transitionNames are required for all sharedElements");
+        }
+        sharedElementNames.put(transitionName, toName);
+    }
+
+    /**
+     * The transition will be delayed until the view with the name passed in is available in the "to" hierarchy. This is
+     * particularly useful for views that don't load instantly, like RecyclerViews. Note that using this method can
+     * potentially lock up your app indefinitely if the view never loads!
+     */
+    protected final void waitOnSharedElementNamed(@NonNull String name) {
+        if (!sharedElementNames.values().contains(name)) {
+            throw new IllegalStateException("Can't wait on a shared element that hasn't been registered using addSharedElement");
+        }
+        waitForTransitionNames.add(name);
+    }
+
+    private static class OneShotPreDrawListener implements OnPreDrawListener, View.OnAttachStateChangeListener {
+
+        private final View view;
+        private ViewTreeObserver viewTreeObserver;
+        private final Runnable runnable;
+        private final boolean preDrawReturnValue;
+
+        private OneShotPreDrawListener(boolean preDrawReturnValue, @NonNull View view, @NonNull Runnable runnable) {
+            this.preDrawReturnValue = preDrawReturnValue;
+            this.view = view;
+            viewTreeObserver = view.getViewTreeObserver();
+            this.runnable = runnable;
+        }
+
+        @NonNull
+        public static OneShotPreDrawListener add(boolean preDrawReturnValue, @NonNull View view, @NonNull Runnable runnable) {
+            OneShotPreDrawListener listener = new OneShotPreDrawListener(preDrawReturnValue, view, runnable);
+            view.getViewTreeObserver().addOnPreDrawListener(listener);
+            view.addOnAttachStateChangeListener(listener);
+            return listener;
+        }
+
+        @Override
+        public boolean onPreDraw() {
+            removeListener();
+            runnable.run();
+            return preDrawReturnValue;
+        }
+
+        private void removeListener() {
+            if (viewTreeObserver.isAlive()) {
+                viewTreeObserver.removeOnPreDrawListener(this);
+            } else {
+                view.getViewTreeObserver().removeOnPreDrawListener(this);
+            }
+            view.removeOnAttachStateChangeListener(this);
+        }
+
+        @Override
+        public void onViewAttachedToWindow(View v) {
+            viewTreeObserver = v.getViewTreeObserver();
+        }
+
+        @Override
+        public void onViewDetachedFromWindow(View v) {
+            removeListener();
+        }
+
+    }
+
+    private static class ViewParentPair {
+        @NonNull final View view;
+        @NonNull final ViewGroup parent;
+
+        ViewParentPair(@NonNull View view, ViewGroup parent) {
+            this.view = view;
+            this.parent = parent;
+        }
+    }
+
+}

conductor-modules/androidx-transition/src/main/java/com/bluelinelabs/conductor/changehandler/androidxtransition/TransitionChangeHandler.java

@@ -0,0 +1,150 @@
+package com.bluelinelabs.conductor.changehandler.androidxtransition;
+
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.transition.Transition;
+import androidx.transition.TransitionManager;
+
+import com.bluelinelabs.conductor.Controller;
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+
+/**
+ * A base {@link ControllerChangeHandler} that facilitates using {@link Transition}s to replace Controller Views.
+ */
+public abstract class TransitionChangeHandler extends ControllerChangeHandler {
+
+    public interface OnTransitionPreparedListener {
+        void onPrepared();
+    }
+
+    boolean canceled;
+    private boolean needsImmediateCompletion;
+
+    /**
+     * Should be overridden to return the Transition to use while replacing Views.
+     *
+     * @param container The container these Views are hosted in
+     * @param from      The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to        The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param isPush    True if this is a push transaction, false if it's a pop
+     */
+    @NonNull
+    protected abstract Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    @Override
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
+        super.onAbortPush(newHandler, newTop);
+
+        canceled = true;
+    }
+
+    @Override
+    public void completeImmediately() {
+        super.completeImmediately();
+
+        needsImmediateCompletion = true;
+    }
+
+    @Nullable
+    private ControllerChangeCompletedListener listener;
+
+    @Override
+    public void performChange(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, final boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
+        listener = changeListener;
+        if (canceled) {
+            changeListener.onChangeCompleted();
+            return;
+        }
+        if (needsImmediateCompletion) {
+            executePropertyChanges(container, from, to, null, isPush);
+            changeListener.onChangeCompleted();
+            return;
+        }
+
+        final Runnable onTransitionNotStarted = new Runnable() {
+            @Override
+            public void run() {
+                changeListener.onChangeCompleted();
+            }
+        };
+
+        final Transition transition = getTransition(container, from, to, isPush);
+        transition.addListener(new Transition.TransitionListener() {
+            @Override
+            public void onTransitionStart(Transition transition) {
+                container.removeCallbacks(onTransitionNotStarted);
+            }
+
+            @Override
+            public void onTransitionEnd(Transition transition) {
+                listener.onChangeCompleted();
+                listener = null;
+            }
+
+            @Override
+            public void onTransitionCancel(Transition transition) {
+                listener.onChangeCompleted();
+                listener = null;
+            }
+
+            @Override
+            public void onTransitionPause(Transition transition) { }
+
+            @Override
+            public void onTransitionResume(Transition transition) { }
+        });
+
+        prepareForTransition(container, from, to, transition, isPush, new OnTransitionPreparedListener() {
+            @Override
+            public void onPrepared() {
+                if (!canceled) {
+                    TransitionManager.beginDelayedTransition(container, transition);
+                    executePropertyChanges(container, from, to, transition, isPush);
+                    container.post(onTransitionNotStarted);
+                }
+            }
+        });
+    }
+
+    @Override
+    public boolean removesFromViewOnPush() {
+        return true;
+    }
+
+    /**
+     * Called before a transition occurs. This can be used to reorder views, set their transition names, etc. The transition will begin
+     * when {@code onTransitionPreparedListener} is called.
+     *
+     * @param container  The container these Views are hosted in
+     * @param from       The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to         The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param transition The transition that is being prepared for
+     * @param isPush     True if this is a push transaction, false if it's a pop
+     */
+    public void prepareForTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @NonNull Transition transition, boolean isPush, @NonNull OnTransitionPreparedListener onTransitionPreparedListener) {
+        onTransitionPreparedListener.onPrepared();
+    }
+
+    /**
+     * This should set all view properties needed for the transition to work properly. By default it removes the "from" view
+     * and adds the "to" view.
+     *
+     * @param container  The container these Views are hosted in
+     * @param from       The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to         The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param transition The transition with which {@code TransitionManager.beginDelayedTransition} has been called. This will be null only if another ControllerChangeHandler immediately overrides this one.
+     * @param isPush     True if this is a push transaction, false if it's a pop
+     */
+    public void executePropertyChanges(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @Nullable Transition transition, boolean isPush) {
+        if (from != null && (removesFromViewOnPush() || !isPush) && from.getParent() == container) {
+            container.removeView(from);
+        }
+        if (to != null && to.getParent() == null) {
+            container.addView(to);
+        }
+    }
+
+}

conductor-modules/androidx-transition/src/main/java/com/bluelinelabs/conductor/internal/TransitionUtils.java

@@ -0,0 +1,184 @@
+package com.bluelinelabs.conductor.internal;
+
+import android.graphics.Rect;
+import android.view.View;
+import android.view.ViewGroup;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.view.ViewCompat;
+import androidx.transition.Transition;
+import androidx.transition.TransitionSet;
+
+import java.util.List;
+import java.util.Map;
+
+public class TransitionUtils {
+
+    public static void findNamedViews(@NonNull Map<String, View> namedViews, View view) {
+        if (view.getVisibility() == View.VISIBLE) {
+            String transitionName = ViewCompat.getTransitionName(view);
+            if (transitionName != null) {
+                namedViews.put(transitionName, view);
+            }
+
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                int childCount = viewGroup.getChildCount();
+                for (int i = 0; i < childCount; i++) {
+                    View child = viewGroup.getChildAt(i);
+                    findNamedViews(namedViews, child);
+                }
+            }
+        }
+    }
+
+    @Nullable
+    public static View findNamedView(@NonNull View view, @NonNull String transitionName) {
+        if (transitionName.equals(ViewCompat.getTransitionName(view))) {
+            return view;
+        }
+
+        if (view instanceof ViewGroup) {
+            ViewGroup viewGroup = (ViewGroup) view;
+            int childCount = viewGroup.getChildCount();
+            for (int i = 0; i < childCount; i++) {
+                View viewWithTransitionName = findNamedView(viewGroup.getChildAt(i), transitionName);
+                if (viewWithTransitionName != null) {
+                    return viewWithTransitionName;
+                }
+            }
+        }
+
+        return null;
+    }
+
+    public static void setEpicenter(@NonNull Transition transition, @Nullable View view) {
+        if (view != null) {
+            final Rect epicenter = new Rect();
+            getBoundsOnScreen(view, epicenter);
+            transition.setEpicenterCallback(new Transition.EpicenterCallback() {
+                @Override
+                public Rect onGetEpicenter(Transition transition) {
+                    return epicenter;
+                }
+            });
+        }
+    }
+
+    public static void getBoundsOnScreen(@NonNull View view, @NonNull Rect epicenter) {
+        int[] loc = new int[2];
+        view.getLocationOnScreen(loc);
+        epicenter.set(loc[0], loc[1], loc[0] + view.getWidth(), loc[1] + view.getHeight());
+    }
+
+    public static void setTargets(@NonNull Transition transition, @NonNull View nonExistentView, @NonNull List<View> sharedViews) {
+        final List<View> views = transition.getTargets();
+        views.clear();
+        final int count = sharedViews.size();
+        for (int i = 0; i < count; i++) {
+            final View view = sharedViews.get(i);
+            bfsAddViewChildren(views, view);
+        }
+        views.add(nonExistentView);
+        sharedViews.add(nonExistentView);
+        addTargets(transition, sharedViews);
+    }
+
+    public static void addTargets(@Nullable Transition transition, @NonNull List<View> views) {
+        if (transition == null) {
+            return;
+        }
+        if (transition instanceof TransitionSet) {
+            TransitionSet set = (TransitionSet) transition;
+            int numTransitions = set.getTransitionCount();
+            for (int i = 0; i < numTransitions; i++) {
+                Transition child = set.getTransitionAt(i);
+                addTargets(child, views);
+            }
+        } else if (!hasSimpleTarget(transition)) {
+            List<View> targets = transition.getTargets();
+            if (isNullOrEmpty(targets)) {
+                int numViews = views.size();
+                for (int i = 0; i < numViews; i++) {
+                    transition.addTarget(views.get(i));
+                }
+            }
+        }
+    }
+
+    public static void replaceTargets(@NonNull Transition transition, @NonNull List<View> oldTargets, @Nullable List<View> newTargets) {
+        if (transition instanceof TransitionSet) {
+            TransitionSet set = (TransitionSet) transition;
+            int numTransitions = set.getTransitionCount();
+            for (int i = 0; i < numTransitions; i++) {
+                Transition child = set.getTransitionAt(i);
+                replaceTargets(child, oldTargets, newTargets);
+            }
+        } else if (!TransitionUtils.hasSimpleTarget(transition)) {
+            List<View> targets = transition.getTargets();
+            if (targets != null && targets.size() == oldTargets.size() && targets.containsAll(oldTargets)) {
+                final int targetCount = newTargets == null ? 0 : newTargets.size();
+                for (int i = 0; i < targetCount; i++) {
+                    transition.addTarget(newTargets.get(i));
+                }
+                for (int i = oldTargets.size() - 1; i >= 0; i--) {
+                    transition.removeTarget(oldTargets.get(i));
+                }
+            }
+        }
+    }
+
+    private static void bfsAddViewChildren(@NonNull final List<View> views, @NonNull final View startView) {
+        final int startIndex = views.size();
+        if (containedBeforeIndex(views, startView, startIndex)) {
+            return; // This child is already in the list, so all its children are also.
+        }
+        views.add(startView);
+        for (int index = startIndex; index < views.size(); index++) {
+            final View view = views.get(index);
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                final int childCount = viewGroup.getChildCount();
+                for (int childIndex = 0; childIndex < childCount; childIndex++) {
+                    final View child = viewGroup.getChildAt(childIndex);
+                    if (!containedBeforeIndex(views, child, startIndex)) {
+                        views.add(child);
+                    }
+                }
+            }
+        }
+    }
+
+    private static boolean containedBeforeIndex(@NonNull List<View> views, View view, int maxIndex) {
+        for (int i = 0; i < maxIndex; i++) {
+            if (views.get(i) == view) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static boolean hasSimpleTarget(@NonNull Transition transition) {
+        return !isNullOrEmpty(transition.getTargetIds())
+                || !isNullOrEmpty(transition.getTargetNames())
+                || !isNullOrEmpty(transition.getTargetTypes());
+    }
+
+    private static boolean isNullOrEmpty(@Nullable List list) {
+        return list == null || list.isEmpty();
+    }
+
+    @NonNull
+    public static TransitionSet mergeTransitions(int ordering, Transition... transitions) {
+        TransitionSet transitionSet = new TransitionSet();
+        for (Transition transition : transitions) {
+            if (transition != null) {
+                transitionSet.addTransition(transition);
+            }
+        }
+        transitionSet.setOrdering(ordering);
+        return transitionSet;
+    }
+
+}

conductor-modules/arch-components-lifecycle/build.gradle

@@ -5,7 +5,6 @@ apply plugin: 'com.android.library'
 
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion rootProject.ext.buildToolsVersion
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_7
@@ -21,9 +20,9 @@ android {
 }
 
 dependencies {
-    compile rootProject.ext.supportAppCompat
-    compile project(':conductor')
+    api rootProject.ext.archComponentsLifecycle
+
+    implementation project(':conductor')
 }
 
-ext.artifactId = 'conductor-support'
-
+ext.artifactId = 'conductor-arch-components-lifecycle'

conductor-modules/arch-components-lifecycle/gradle.properties

@@ -0,0 +1,3 @@
+POM_NAME=Conductor Architecture Components Lifecycle Extensions
+POM_ARTIFACT_ID=conductor-archlifecycle
+POM_PACKAGING=aar

conductor-modules/arch-components-lifecycle/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest package="com.bluelinelabs.conductor.archlifecycle">
+    <application />
+</manifest>

conductor-modules/arch-components-lifecycle/src/main/java/com/bluelinelabs/conductor/archlifecycle/ControllerLifecycleOwner.java

@@ -0,0 +1,65 @@
+package com.bluelinelabs.conductor.archlifecycle;
+
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.Lifecycle.Event;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.LifecycleRegistry;
+import android.content.Context;
+import androidx.annotation.NonNull;
+import android.view.View;
+
+import com.bluelinelabs.conductor.Controller;
+import com.bluelinelabs.conductor.Controller.LifecycleListener;
+
+public class ControllerLifecycleOwner implements LifecycleOwner {
+
+    private final LifecycleRegistry lifecycleRegistry;
+
+    public <T extends Controller & LifecycleOwner> ControllerLifecycleOwner(@NonNull T lifecycleController) {
+        lifecycleRegistry = new LifecycleRegistry(lifecycleController); // --> State.INITIALIZED
+
+        lifecycleController.addLifecycleListener(new LifecycleListener() {
+            @Override
+            public void postContextAvailable(@NonNull Controller controller, @NonNull Context context) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_CREATE); // --> State.CREATED;
+            }
+
+            @Override
+            public void postCreateView(@NonNull Controller controller, @NonNull View view) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_START); // --> State.STARTED;
+            }
+
+            @Override
+            public void postAttach(@NonNull Controller controller, @NonNull View view) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_RESUME); // --> State.RESUMED;
+            }
+
+            @Override
+            public void preDetach(@NonNull Controller controller, @NonNull View view) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_PAUSE); // --> State.STARTED;
+            }
+
+            @Override
+            public void preDestroyView(@NonNull Controller controller, @NonNull View view) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_STOP); // --> State.CREATED;
+            }
+
+            @Override
+            public void preContextUnavailable(@NonNull Controller controller, @NonNull Context context) {
+                // do nothing
+            }
+
+            @Override
+            public void preDestroy(@NonNull Controller controller) {
+                lifecycleRegistry.handleLifecycleEvent(Event.ON_DESTROY); // --> State.DESTROYED;
+            }
+
+        });
+    }
+
+    @Override @NonNull
+    public Lifecycle getLifecycle() {
+        return lifecycleRegistry;
+    }
+
+}

conductor-modules/arch-components-lifecycle/src/main/java/com/bluelinelabs/conductor/archlifecycle/LifecycleController.java

@@ -0,0 +1,28 @@
+package com.bluelinelabs.conductor.archlifecycle;
+
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleOwner;
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.bluelinelabs.conductor.Controller;
+
+public abstract class LifecycleController extends Controller implements LifecycleOwner {
+
+    private final ControllerLifecycleOwner lifecycleOwner = new ControllerLifecycleOwner(this);
+
+    public LifecycleController() {
+        super();
+    }
+
+    public LifecycleController(@Nullable Bundle args) {
+        super(args);
+    }
+
+    @Override @NonNull
+    public Lifecycle getLifecycle() {
+        return lifecycleOwner.getLifecycle();
+    }
+
+}

conductor-modules/arch-components-lifecycle/src/main/java/com/bluelinelabs/conductor/archlifecycle/LifecycleRestoreViewOnCreateController.java

@@ -0,0 +1,28 @@
+package com.bluelinelabs.conductor.archlifecycle;
+
+import androidx.lifecycle.Lifecycle;
+import androidx.lifecycle.LifecycleOwner;
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.bluelinelabs.conductor.RestoreViewOnCreateController;
+
+public abstract class LifecycleRestoreViewOnCreateController extends RestoreViewOnCreateController implements LifecycleOwner {
+
+    private final ControllerLifecycleOwner mLifecycleOwner = new ControllerLifecycleOwner(this);
+
+    public LifecycleRestoreViewOnCreateController() {
+        super();
+    }
+
+    public LifecycleRestoreViewOnCreateController(@Nullable Bundle args) {
+        super(args);
+    }
+
+    @Override @NonNull
+    public Lifecycle getLifecycle() {
+        return mLifecycleOwner.getLifecycle();
+    }
+
+}

conductor-modules/autodispose/build.gradle

@@ -0,0 +1,30 @@
+apply from: rootProject.file('dependencies.gradle')
+apply from: rootProject.file('gradle-mvn-push.gradle')
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
+
+    defaultConfig {
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
+        versionCode Integer.parseInt(project.VERSION_CODE)
+        versionName project.VERSION_NAME
+    }
+}
+
+dependencies {
+    api rootProject.ext.rxJava2
+    api rootProject.ext.autodispose
+    api rootProject.ext.autodisposeLifecycle
+
+    implementation project(':conductor')
+}
+
+ext.artifactId = 'conductor-autodispose'

conductor-modules/autodispose/gradle.properties

@@ -0,0 +1,3 @@
+POM_NAME=Conductor AutoDispose Extensions
+POM_ARTIFACT_ID=conductor-autodispose
+POM_PACKAGING=aar

conductor-modules/autodispose/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest package="com.bluelinelabs.conductor.autodispose">
+    <application />
+</manifest>

conductor-modules/autodispose/src/main/java/com/bluelinelabs/conductor/autodispose/ControllerEvent.java

@@ -0,0 +1,14 @@
+package com.bluelinelabs.conductor.autodispose;
+
+public enum ControllerEvent {
+
+    CREATE,
+    CONTEXT_AVAILABLE,
+    CREATE_VIEW,
+    ATTACH,
+    DETACH,
+    DESTROY_VIEW,
+    CONTEXT_UNAVAILABLE,
+    DESTROY
+
+}

conductor-modules/autodispose/src/main/java/com/bluelinelabs/conductor/autodispose/ControllerLifecycleSubjectHelper.java

@@ -0,0 +1,71 @@
+package com.bluelinelabs.conductor.autodispose;
+
+import android.content.Context;
+import androidx.annotation.NonNull;
+import android.view.View;
+
+import com.bluelinelabs.conductor.Controller;
+import com.uber.autodispose.OutsideScopeException;
+
+import io.reactivex.subjects.BehaviorSubject;
+
+public class ControllerLifecycleSubjectHelper {
+    private ControllerLifecycleSubjectHelper() { }
+
+    @NonNull
+    public static BehaviorSubject<ControllerEvent> create(@NonNull Controller controller) {
+        ControllerEvent initialState;
+        if (controller.isBeingDestroyed() || controller.isDestroyed()) {
+            throw new OutsideScopeException("Cannot bind to Controller lifecycle when outside of it.");
+        } else if (controller.isAttached()) {
+            initialState = ControllerEvent.ATTACH;
+        } else if (controller.getView() != null) {
+            initialState = ControllerEvent.CREATE_VIEW;
+        } else if (controller.getActivity() != null) {
+            initialState = ControllerEvent.CONTEXT_AVAILABLE;
+        } else {
+            initialState = ControllerEvent.CREATE;
+        }
+
+        final BehaviorSubject<ControllerEvent> subject = BehaviorSubject.createDefault(initialState);
+
+        controller.addLifecycleListener(new Controller.LifecycleListener() {
+            @Override
+            public void preContextAvailable(@NonNull Controller controller) {
+                subject.onNext(ControllerEvent.CONTEXT_AVAILABLE);
+            }
+
+            @Override
+            public void preCreateView(@NonNull Controller controller) {
+                subject.onNext(ControllerEvent.CREATE_VIEW);
+            }
+
+            @Override
+            public void preAttach(@NonNull Controller controller, @NonNull View view) {
+                subject.onNext(ControllerEvent.ATTACH);
+            }
+
+            @Override
+            public void preDetach(@NonNull Controller controller, @NonNull View view) {
+                subject.onNext(ControllerEvent.DETACH);
+            }
+
+            @Override
+            public void preDestroyView(@NonNull Controller controller, @NonNull View view) {
+                subject.onNext(ControllerEvent.DESTROY_VIEW);
+            }
+
+            @Override
+            public void preContextUnavailable(@NonNull Controller controller, @NonNull Context context) {
+                subject.onNext(ControllerEvent.CONTEXT_UNAVAILABLE);
+            }
+
+            @Override
+            public void preDestroy(@NonNull Controller controller) {
+                subject.onNext(ControllerEvent.DESTROY);
+            }
+        });
+
+        return subject;
+    }
+}

conductor-modules/autodispose/src/main/java/com/bluelinelabs/conductor/autodispose/ControllerScopeProvider.java

@@ -0,0 +1,81 @@
+package com.bluelinelabs.conductor.autodispose;
+
+import androidx.annotation.NonNull;
+
+import com.bluelinelabs.conductor.Controller;
+import com.uber.autodispose.OutsideScopeException;
+import com.uber.autodispose.lifecycle.LifecycleScopeProvider;
+import com.uber.autodispose.lifecycle.LifecycleScopes;
+import com.uber.autodispose.lifecycle.CorrespondingEventsFunction;
+
+import io.reactivex.CompletableSource;
+import io.reactivex.Observable;
+import io.reactivex.subjects.BehaviorSubject;
+
+public class ControllerScopeProvider implements LifecycleScopeProvider<ControllerEvent> {
+    private static final CorrespondingEventsFunction<ControllerEvent> CORRESPONDING_EVENTS =
+            new CorrespondingEventsFunction<ControllerEvent>() {
+                @Override
+                public ControllerEvent apply(ControllerEvent lastEvent) throws OutsideScopeException {
+                    switch (lastEvent) {
+                        case CREATE:
+                            return ControllerEvent.DESTROY;
+                        case CONTEXT_AVAILABLE:
+                            return ControllerEvent.CONTEXT_UNAVAILABLE;
+                        case CREATE_VIEW:
+                            return ControllerEvent.DESTROY_VIEW;
+                        case ATTACH:
+                            return ControllerEvent.DETACH;
+                        case DETACH:
+                            return ControllerEvent.DESTROY;
+                        default:
+                            throw new OutsideScopeException("Cannot bind to Controller lifecycle when outside of it.");
+                    }
+                }
+            };
+
+    @NonNull private final BehaviorSubject<ControllerEvent> lifecycleSubject;
+    @NonNull private final CorrespondingEventsFunction<ControllerEvent> correspondingEventsFunction;
+
+    public static ControllerScopeProvider from(@NonNull Controller controller) {
+        return new ControllerScopeProvider(controller, CORRESPONDING_EVENTS);
+    }
+
+    public static ControllerScopeProvider from(@NonNull Controller controller, @NonNull final ControllerEvent untilEvent) {
+        return new ControllerScopeProvider(controller, new CorrespondingEventsFunction<ControllerEvent>() {
+            @Override
+            public ControllerEvent apply(ControllerEvent controllerEvent) {
+                return untilEvent;
+            }
+        });
+    }
+
+    public static ControllerScopeProvider from(@NonNull Controller controller, @NonNull final CorrespondingEventsFunction<ControllerEvent> correspondingEventsFunction) {
+        return new ControllerScopeProvider(controller, correspondingEventsFunction);
+    }
+
+    private ControllerScopeProvider(@NonNull Controller controller, @NonNull CorrespondingEventsFunction<ControllerEvent> correspondingEventsFunction) {
+        lifecycleSubject = ControllerLifecycleSubjectHelper.create(controller);
+        this.correspondingEventsFunction = correspondingEventsFunction;
+    }
+
+    @Override
+    public Observable<ControllerEvent> lifecycle() {
+        return lifecycleSubject.hide();
+    }
+
+    @Override
+    public CorrespondingEventsFunction<ControllerEvent> correspondingEvents() {
+        return correspondingEventsFunction;
+    }
+
+    @Override
+    public ControllerEvent peekLifecycle() {
+        return lifecycleSubject.getValue();
+    }
+
+    @Override
+    public CompletableSource requestScope() throws Exception {
+        return LifecycleScopes.resolveScopeFromLifecycle(this);
+    }
+}

conductor-modules/rxlifecycle/build.gradle

@@ -5,7 +5,6 @@ apply plugin: 'com.android.library'
 
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion rootProject.ext.buildToolsVersion
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_7
@@ -21,12 +20,11 @@ android {
 }
 
 dependencies {
-    compile rootProject.ext.rxJava
-    compile rootProject.ext.rxLifecycle
-    compile rootProject.ext.rxLifecycleAndroid
+    api rootProject.ext.rxJava
+    api rootProject.ext.rxLifecycle
+    api rootProject.ext.rxLifecycleAndroid
 
-    compile project(':conductor')
+    implementation project(':conductor')
 }
 
 ext.artifactId = 'conductor-rxlifecycle'
-

conductor-modules/rxlifecycle/src/main/AndroidManifest.xml

@@ -1,3 +1,3 @@
 <manifest package="com.bluelinelabs.conductor.rxlifecycle">
     <application />
-</manifest>
+</manifest>

conductor-modules/rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/ControllerEvent.java

@@ -3,10 +3,12 @@ package com.bluelinelabs.conductor.rxlifecycle;
 public enum ControllerEvent {
 
     CREATE,
+    CONTEXT_AVAILABLE,
     CREATE_VIEW,
     ATTACH,
     DETACH,
     DESTROY_VIEW,
+    CONTEXT_UNAVAILABLE,
     DESTROY
 
 }

conductor-modules/rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/ControllerLifecycleSubjectHelper.java

@@ -1,10 +1,12 @@
 package com.bluelinelabs.conductor.rxlifecycle;
 
-import android.support.annotation.NonNull;
+import android.content.Context;
+import androidx.annotation.NonNull;
 import android.view.View;
 
 import com.bluelinelabs.conductor.Controller;
 import com.bluelinelabs.conductor.Controller.LifecycleListener;
+import com.trello.rxlifecycle.OutsideLifecycleException;
 
 import rx.subjects.BehaviorSubject;
 
@@ -17,9 +19,27 @@ public class ControllerLifecycleSubjectHelper {
     private ControllerLifecycleSubjectHelper() { }
 
     public static BehaviorSubject<ControllerEvent> create(Controller controller) {
-        final BehaviorSubject<ControllerEvent> subject = BehaviorSubject.create(ControllerEvent.CREATE);
+        ControllerEvent initialState;
+        if (controller.isBeingDestroyed() || controller.isDestroyed()) {
+            throw new OutsideLifecycleException("Cannot bind to Controller lifecycle when outside of it.");
+        } else if (controller.isAttached()) {
+            initialState = ControllerEvent.ATTACH;
+        } else if (controller.getView() != null) {
+            initialState = ControllerEvent.CREATE_VIEW;
+        } else if (controller.getActivity() != null) {
+            initialState = ControllerEvent.CONTEXT_AVAILABLE;
+        } else {
+            initialState = ControllerEvent.CREATE;
+        }
+
+        final BehaviorSubject<ControllerEvent> subject = BehaviorSubject.create(initialState);
 
         controller.addLifecycleListener(new LifecycleListener() {
+            @Override
+            public void preContextAvailable(@NonNull Controller controller) {
+                subject.onNext(ControllerEvent.CONTEXT_AVAILABLE);
+            }
+
             @Override
             public void preCreateView(@NonNull Controller controller) {
                 subject.onNext(ControllerEvent.CREATE_VIEW);
@@ -40,6 +60,11 @@ public class ControllerLifecycleSubjectHelper {
                 subject.onNext(ControllerEvent.DESTROY_VIEW);
             }
 
+            @Override
+            public void preContextUnavailable(@NonNull Controller controller, @NonNull Context context) {
+                subject.onNext(ControllerEvent.CONTEXT_UNAVAILABLE);
+            }
+
             @Override
             public void preDestroy(@NonNull Controller controller) {
                 subject.onNext(ControllerEvent.DESTROY);

conductor-modules/rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/RxController.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor.rxlifecycle;
 
 import android.os.Bundle;
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
+import androidx.annotation.CheckResult;
+import androidx.annotation.NonNull;
 
 import com.bluelinelabs.conductor.Controller;
 import com.trello.rxlifecycle.LifecycleProvider;
@@ -49,4 +49,4 @@ public abstract class RxController extends Controller implements LifecycleProvid
         return RxControllerLifecycle.bindController(lifecycleSubject);
     }
 
-}
+}

conductor-modules/rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/RxControllerLifecycle.java

@@ -1,7 +1,7 @@
 package com.bluelinelabs.conductor.rxlifecycle;
 
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
+import androidx.annotation.CheckResult;
+import androidx.annotation.NonNull;
 
 import com.trello.rxlifecycle.LifecycleTransformer;
 import com.trello.rxlifecycle.OutsideLifecycleException;
@@ -17,7 +17,7 @@ public class RxControllerLifecycle {
      * {@link com.trello.rxlifecycle.android.RxLifecycleAndroid#bindFragment(Observable)}.
      *
      * @param lifecycle the lifecycle sequence of a Controller
-     * @return a reusable {@link Observable.Transformer} that unsubscribes the source during the Controller lifecycle
+     * @return a reusable {@link rx.Observable.Transformer} that unsubscribes the source during the Controller lifecycle
      */
     @NonNull
     @CheckResult
@@ -32,6 +32,8 @@ public class RxControllerLifecycle {
                     switch (lastEvent) {
                         case CREATE:
                             return ControllerEvent.DESTROY;
+                        case CONTEXT_AVAILABLE:
+                            return ControllerEvent.CONTEXT_UNAVAILABLE;
                         case ATTACH:
                             return ControllerEvent.DETACH;
                         case CREATE_VIEW:

conductor-modules/rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/RxRestoreViewOnCreateController.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor.rxlifecycle;
 
 import android.os.Bundle;
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
+import androidx.annotation.CheckResult;
+import androidx.annotation.NonNull;
 
 import com.bluelinelabs.conductor.RestoreViewOnCreateController;
 import com.trello.rxlifecycle.LifecycleProvider;
@@ -49,4 +49,4 @@ public abstract class RxRestoreViewOnCreateController extends RestoreViewOnCreat
         return RxControllerLifecycle.bindController(lifecycleSubject);
     }
 
-}
+}

conductor-modules/rxlifecycle2/build.gradle

@@ -5,7 +5,6 @@ apply plugin: 'com.android.library'
 
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion rootProject.ext.buildToolsVersion
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_7
@@ -21,11 +20,11 @@ android {
 }
 
 dependencies {
-    compile rootProject.ext.rxJava2
-    compile rootProject.ext.rxLifecycle2
-    compile rootProject.ext.rxLifecycleAndroid2
+    api rootProject.ext.rxJava2
+    api rootProject.ext.rxLifecycle2
+    api rootProject.ext.rxLifecycleAndroid2
 
-    compile project(':conductor')
+    implementation project(':conductor')
 }
 
 ext.artifactId = 'conductor-rxlifecycle2'

conductor-modules/rxlifecycle2/src/main/AndroidManifest.xml

@@ -1,4 +1,3 @@
 <manifest package="com.bluelinelabs.conductor.rxlifecycle2">
     <application />
 </manifest>
-

conductor-modules/rxlifecycle2/src/main/java/com/bluelinelabs/conductor/rxlifecycle2/ControllerEvent.java

@@ -3,10 +3,12 @@ package com.bluelinelabs.conductor.rxlifecycle2;
 public enum ControllerEvent {
 
     CREATE,
+    CONTEXT_AVAILABLE,
     CREATE_VIEW,
     ATTACH,
     DETACH,
     DESTROY_VIEW,
+    CONTEXT_UNAVAILABLE,
     DESTROY
 
 }

conductor-modules/rxlifecycle2/src/main/java/com/bluelinelabs/conductor/rxlifecycle2/ControllerLifecycleSubjectHelper.java

@@ -1,18 +1,40 @@
 package com.bluelinelabs.conductor.rxlifecycle2;
 
-import android.support.annotation.NonNull;
+import android.content.Context;
+import androidx.annotation.NonNull;
 import android.view.View;
+
 import com.bluelinelabs.conductor.Controller;
+import com.trello.rxlifecycle2.OutsideLifecycleException;
+
 import io.reactivex.subjects.BehaviorSubject;
 
 public class ControllerLifecycleSubjectHelper {
     private ControllerLifecycleSubjectHelper() {
     }
 
-    public static BehaviorSubject<ControllerEvent> create(Controller controller){
-        final BehaviorSubject<ControllerEvent> subject = BehaviorSubject.createDefault(ControllerEvent.CREATE);
+    public static BehaviorSubject<ControllerEvent> create(Controller controller) {
+        ControllerEvent initialState;
+        if (controller.isBeingDestroyed() || controller.isDestroyed()) {
+            throw new OutsideLifecycleException("Cannot bind to Controller lifecycle when outside of it.");
+        } else if (controller.isAttached()) {
+            initialState = ControllerEvent.ATTACH;
+        } else if (controller.getView() != null) {
+            initialState = ControllerEvent.CREATE_VIEW;
+        } else if (controller.getActivity() != null) {
+            initialState = ControllerEvent.CONTEXT_AVAILABLE;
+        } else {
+            initialState = ControllerEvent.CREATE;
+        }
+
+        final BehaviorSubject<ControllerEvent> subject = BehaviorSubject.createDefault(initialState);
 
         controller.addLifecycleListener(new Controller.LifecycleListener() {
+            @Override
+            public void preContextAvailable(@NonNull Controller controller) {
+                subject.onNext(ControllerEvent.CONTEXT_AVAILABLE);
+            }
+
             @Override
             public void preCreateView(@NonNull Controller controller) {
                 subject.onNext(ControllerEvent.CREATE_VIEW);
@@ -33,6 +55,11 @@ public class ControllerLifecycleSubjectHelper {
                 subject.onNext(ControllerEvent.DESTROY_VIEW);
             }
 
+            @Override
+            public void preContextUnavailable(@NonNull Controller controller, @NonNull Context context) {
+                subject.onNext(ControllerEvent.CONTEXT_UNAVAILABLE);
+            }
+
             @Override
             public void preDestroy(@NonNull Controller controller) {
                 subject.onNext(ControllerEvent.DESTROY);

conductor-modules/rxlifecycle2/src/main/java/com/bluelinelabs/conductor/rxlifecycle2/RxController.java

@@ -1,9 +1,9 @@
 package com.bluelinelabs.conductor.rxlifecycle2;
 
 import android.os.Bundle;
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.CheckResult;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import com.bluelinelabs.conductor.Controller;
 import com.trello.rxlifecycle2.LifecycleProvider;
 import com.trello.rxlifecycle2.LifecycleTransformer;

conductor-modules/rxlifecycle2/src/main/java/com/bluelinelabs/conductor/rxlifecycle2/RxControllerLifecycle.java

@@ -1,6 +1,6 @@
 package com.bluelinelabs.conductor.rxlifecycle2;
 
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 import com.trello.rxlifecycle2.LifecycleTransformer;
 import com.trello.rxlifecycle2.OutsideLifecycleException;
 import com.trello.rxlifecycle2.RxLifecycle;
@@ -27,6 +27,8 @@ public class RxControllerLifecycle {
                 switch (lastEvent) {
                     case CREATE:
                         return ControllerEvent.DESTROY;
+                    case CONTEXT_AVAILABLE:
+                        return ControllerEvent.CONTEXT_UNAVAILABLE;
                     case ATTACH:
                         return ControllerEvent.DETACH;
                     case CREATE_VIEW:

conductor-modules/rxlifecycle2/src/main/java/com/bluelinelabs/conductor/rxlifecycle2/RxRestoreViewOnCreateController.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor.rxlifecycle2;
 
 import android.os.Bundle;
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
+import androidx.annotation.CheckResult;
+import androidx.annotation.NonNull;
 import com.bluelinelabs.conductor.RestoreViewOnCreateController;
 import com.trello.rxlifecycle2.LifecycleProvider;
 import com.trello.rxlifecycle2.LifecycleTransformer;

conductor-modules/viewpager/build.gradle

@@ -0,0 +1,40 @@
+buildscript {
+    repositories {
+        jcenter()
+    }
+    dependencies {
+        classpath 'de.mobilej.unmock:UnMockPlugin:0.6.5'
+    }
+}
+
+apply plugin: 'com.android.library'
+apply plugin: 'de.mobilej.unmock'
+
+android {
+    compileSdkVersion rootProject.ext.compileSdkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_7
+        targetCompatibility JavaVersion.VERSION_1_7
+    }
+
+    defaultConfig {
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
+        versionCode Integer.parseInt(project.VERSION_CODE)
+        versionName project.VERSION_NAME
+    }
+}
+
+dependencies {
+    testImplementation rootProject.ext.junit
+    testImplementation rootProject.ext.roboelectric
+
+    implementation rootProject.ext.androidxAppCompat
+    implementation project(':conductor')
+}
+
+ext.artifactId = 'conductor-viewpager'
+
+apply from: rootProject.file('dependencies.gradle')
+apply from: rootProject.file('gradle-mvn-push.gradle')

conductor-modules/viewpager/gradle.properties

@@ -0,0 +1,3 @@
+POM_NAME=Conductor PagerAdapter
+POM_ARTIFACT_ID=conductor-viewpager
+POM_PACKAGING=aar

conductor-modules/viewpager/src/main/AndroidManifest.xml

@@ -1,3 +1,3 @@
 <manifest package="com.bluelinelabs.conductor.support">
     <application />
-</manifest>
+</manifest>

conductor-modules/viewpager/src/main/java/com/bluelinelabs/conductor/support/RouterPagerAdapter.java

@@ -0,0 +1,210 @@
+package com.bluelinelabs.conductor.support;
+
+import android.os.Bundle;
+import android.os.Parcelable;
+import android.util.SparseArray;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.bluelinelabs.conductor.Controller;
+import com.bluelinelabs.conductor.Router;
+import com.bluelinelabs.conductor.RouterTransaction;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.viewpager.widget.PagerAdapter;
+
+/**
+ * An adapter for ViewPagers that uses Routers as pages
+ */
+public abstract class RouterPagerAdapter extends PagerAdapter {
+
+    private static final String KEY_SAVED_PAGES = "RouterPagerAdapter.savedStates";
+    private static final String KEY_TAGS_KEYS = "RouterPagerAdapter.tags.keys";
+    private static final String KEY_TAGS_VALUES = "RouterPagerAdapter.tags.values";
+    private static final String KEY_MAX_PAGES_TO_STATE_SAVE = "RouterPagerAdapter.maxPagesToStateSave";
+    private static final String KEY_SAVE_PAGE_HISTORY = "RouterPagerAdapter.savedPageHistory";
+
+    private final Controller host;
+    private int maxPagesToStateSave = Integer.MAX_VALUE;
+    private Map<Integer, String> tags = new HashMap<>();
+    private SparseArray<Bundle> savedPages = new SparseArray<>();
+    private SparseArray<Router> visibleRouters = new SparseArray<>();
+    private ArrayList<Integer> savedPageHistory = new ArrayList<>();
+    private Router currentPrimaryRouter;
+
+    /**
+     * Creates a new RouterPagerAdapter using the passed host.
+     */
+    public RouterPagerAdapter(@NonNull Controller host) {
+        this.host = host;
+    }
+
+    /**
+     * Called when a router is instantiated. Here the router's root should be set if needed.
+     *
+     * @param router   The router used for the page
+     * @param position The page position to be instantiated.
+     */
+    public abstract void configureRouter(@NonNull Router router, int position);
+
+    /**
+     * Sets the maximum number of pages that will have their states saved. When this number is exceeded,
+     * the page that was state saved least recently will have its state removed from the save data.
+     */
+    public void setMaxPagesToStateSave(int maxPagesToStateSave) {
+        if (maxPagesToStateSave < 0) {
+            throw new IllegalArgumentException("Only positive integers may be passed for maxPagesToStateSave.");
+        }
+
+        this.maxPagesToStateSave = maxPagesToStateSave;
+
+        ensurePagesSaved();
+    }
+
+    @Override
+    public Object instantiateItem(ViewGroup container, int position) {
+        final String name = makeRouterName(container.getId(), getItemId(position));
+
+        // Ensure we don't try to restore state for a router with a different ID just because
+        // the position was reused. Fixes https://github.com/bluelinelabs/Conductor/issues/582
+        if (tags.get(position) != null && !tags.get(position).equals(name)) {
+            savedPages.remove(position);
+        }
+
+        Router router = host.getChildRouter(container, name);
+        if (!router.hasRootController()) {
+            Bundle routerSavedState = savedPages.get(position);
+
+            if (routerSavedState != null) {
+                router.restoreInstanceState(routerSavedState);
+                savedPages.remove(position);
+                savedPageHistory.remove((Integer) position);
+            }
+        }
+
+        router.rebindIfNeeded();
+        configureRouter(router, position);
+
+        if (router != currentPrimaryRouter) {
+            for (RouterTransaction transaction : router.getBackstack()) {
+                transaction.controller().setOptionsMenuHidden(true);
+            }
+        }
+
+        tags.put(position, name);
+        visibleRouters.put(position, router);
+        return router;
+    }
+
+    @Override
+    public void destroyItem(ViewGroup container, int position, Object object) {
+        Router router = (Router)object;
+
+        Bundle savedState = new Bundle();
+        router.saveInstanceState(savedState);
+        savedPages.put(position, savedState);
+
+        savedPageHistory.remove((Integer) position);
+        savedPageHistory.add(position);
+
+        ensurePagesSaved();
+
+        host.removeChildRouter(router);
+
+        visibleRouters.remove(position);
+    }
+
+    @Override
+    public void setPrimaryItem(ViewGroup container, int position, Object object) {
+        Router router = (Router)object;
+        if (router != currentPrimaryRouter) {
+            if (currentPrimaryRouter != null) {
+                for (RouterTransaction transaction : currentPrimaryRouter.getBackstack()) {
+                    transaction.controller().setOptionsMenuHidden(true);
+                }
+            }
+            if (router != null) {
+                for (RouterTransaction transaction : router.getBackstack()) {
+                    transaction.controller().setOptionsMenuHidden(false);
+                }
+            }
+            currentPrimaryRouter = router;
+        }
+    }
+
+    @Override
+    public boolean isViewFromObject(View view, Object object) {
+        Router router = (Router)object;
+        final List<RouterTransaction> backstack = router.getBackstack();
+        for (RouterTransaction transaction : backstack) {
+            if (transaction.controller().getView() == view) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public Parcelable saveState() {
+        Bundle bundle = new Bundle();
+        bundle.putSparseParcelableArray(KEY_SAVED_PAGES, savedPages);
+        bundle.putIntegerArrayList(KEY_TAGS_KEYS, new ArrayList<>(tags.keySet()));
+        bundle.putStringArrayList(KEY_TAGS_VALUES, new ArrayList<>(tags.values()));
+        bundle.putInt(KEY_MAX_PAGES_TO_STATE_SAVE, maxPagesToStateSave);
+        bundle.putIntegerArrayList(KEY_SAVE_PAGE_HISTORY, savedPageHistory);
+        return bundle;
+    }
+
+    @Override
+    public void restoreState(Parcelable state, ClassLoader loader) {
+        Bundle bundle = (Bundle)state;
+        if (state != null) {
+            savedPages = bundle.getSparseParcelableArray(KEY_SAVED_PAGES);
+            maxPagesToStateSave = bundle.getInt(KEY_MAX_PAGES_TO_STATE_SAVE);
+            savedPageHistory = bundle.getIntegerArrayList(KEY_SAVE_PAGE_HISTORY);
+
+            List<Integer> tagsKeys = bundle.getIntegerArrayList(KEY_TAGS_KEYS);
+            List<String> tagsValues = bundle.getStringArrayList(KEY_TAGS_VALUES);
+            if (tagsKeys != null && tagsValues != null && tagsKeys.size() == tagsValues.size()) {
+                for (int i = 0; i < tagsKeys.size(); i++) {
+                    tags.put(tagsKeys.get(i), tagsValues.get(i));
+                }
+            }
+        }
+    }
+
+    /**
+     * Returns the already instantiated Router in the specified position or {@code null} if there
+     * is no router associated with this position.
+     */
+    @Nullable
+    public Router getRouter(int position) {
+        return visibleRouters.get(position);
+    }
+
+    public long getItemId(int position) {
+        return position;
+    }
+
+    SparseArray<Bundle> getSavedPages() {
+        return savedPages;
+    }
+
+    private void ensurePagesSaved() {
+        while (savedPages.size() > maxPagesToStateSave) {
+            int positionToRemove = savedPageHistory.remove(0);
+            savedPages.remove(positionToRemove);
+        }
+    }
+
+    private static String makeRouterName(int viewId, long id) {
+        return viewId + ":" + id;
+    }
+
+}

conductor-modules/viewpager/src/test/java/com/bluelinelabs/conductor/support/StateSaveTests.java

@@ -0,0 +1,113 @@
+package com.bluelinelabs.conductor.support;
+
+import android.app.Activity;
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import android.util.SparseArray;
+import android.widget.FrameLayout;
+
+import com.bluelinelabs.conductor.Conductor;
+import com.bluelinelabs.conductor.Router;
+import com.bluelinelabs.conductor.RouterTransaction;
+import com.bluelinelabs.conductor.support.util.FakePager;
+import com.bluelinelabs.conductor.support.util.TestController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.Robolectric;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.android.controller.ActivityController;
+import org.robolectric.annotation.Config;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class StateSaveTests {
+
+    private FakePager pager;
+    private RouterPagerAdapter pagerAdapter;
+
+    public void createActivityController(Bundle savedInstanceState) {
+        ActivityController<Activity> activityController = Robolectric.buildActivity(Activity.class).create().start().resume();
+        Router router = Conductor.attachRouter(activityController.get(), new FrameLayout(activityController.get()), savedInstanceState);
+        TestController controller = new TestController();
+        router.setRoot(RouterTransaction.with(controller));
+
+        pager = new FakePager(new FrameLayout(activityController.get()));
+        pager.setOffscreenPageLimit(1);
+
+        pagerAdapter = new RouterPagerAdapter(controller) {
+            @Override
+            public void configureRouter(@NonNull Router router, int position) {
+                if (!router.hasRootController()) {
+                    router.setRoot(RouterTransaction.with(new TestController()));
+                }
+            }
+
+            @Override
+            public int getCount() {
+                return 20;
+            }
+        };
+
+        pager.setAdapter(pagerAdapter);
+    }
+
+    @Before
+    public void setup() {
+        createActivityController(null);
+    }
+
+    @Test
+    public void testNoMaxSaves() {
+        // Load all pages
+        for (int i = 0; i < pagerAdapter.getCount(); i++) {
+            pager.pageTo(i);
+        }
+
+        pager.pageTo(pagerAdapter.getCount() / 2);
+
+        // Ensure all non-visible pages are saved
+        assertEquals(pagerAdapter.getCount() - 1 - pager.getOffscreenPageLimit() * 2, pagerAdapter.getSavedPages().size());
+    }
+
+    @Test
+    public void testMaxSavedSet() {
+        final int maxPages = 3;
+        pagerAdapter.setMaxPagesToStateSave(maxPages);
+
+        // Load all pages
+        for (int i = 0; i < pagerAdapter.getCount(); i++) {
+            pager.pageTo(i);
+        }
+
+        final int firstSelectedItem = pagerAdapter.getCount() / 2;
+        pager.pageTo(firstSelectedItem);
+
+        SparseArray<Bundle> savedPages = pagerAdapter.getSavedPages();
+
+        // Ensure correct number of pages are saved
+        assertEquals(maxPages, savedPages.size());
+
+        // Ensure correct pages are saved
+        assertEquals(pagerAdapter.getCount() - 3, savedPages.keyAt(0));
+        assertEquals(pagerAdapter.getCount() - 2, savedPages.keyAt(1));
+        assertEquals(pagerAdapter.getCount() - 1, savedPages.keyAt(2));
+
+        final int secondSelectedItem = 1;
+        pager.pageTo(secondSelectedItem);
+
+        savedPages = pagerAdapter.getSavedPages();
+
+        // Ensure correct number of pages are saved
+        assertEquals(maxPages, savedPages.size());
+
+        // Ensure correct pages are saved
+        assertEquals(firstSelectedItem - 1, savedPages.keyAt(0));
+        assertEquals(firstSelectedItem, savedPages.keyAt(1));
+        assertEquals(firstSelectedItem + 1, savedPages.keyAt(2));
+    }
+
+}

conductor-modules/viewpager/src/test/java/com/bluelinelabs/conductor/support/util/FakePager.java

@@ -0,0 +1,61 @@
+package com.bluelinelabs.conductor.support.util;
+
+import android.util.SparseArray;
+import android.view.ViewGroup;
+
+import com.bluelinelabs.conductor.support.RouterPagerAdapter;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class FakePager {
+
+    private ViewGroup container;
+    private int offscreenPageLimit;
+    private final SparseArray<Object> pages = new SparseArray<>();
+
+    private RouterPagerAdapter adapter;
+
+    public FakePager(ViewGroup container) {
+        this.container = container;
+    }
+
+    public void setAdapter(RouterPagerAdapter adapter) {
+        this.adapter = adapter;
+    }
+
+    public void pageTo(int page) {
+        int firstPage = Math.max(0, page - offscreenPageLimit);
+        int lastPage = Math.min(adapter.getCount() - 1, page + offscreenPageLimit);
+
+        List<Integer> pagesI = new ArrayList<>();
+        for (int i = 0; i < pages.size(); i++) {
+            pagesI.add(pages.keyAt(i));
+        }
+
+        for (int i = pages.size() - 1; i >= 0; i--) {
+            int key = pages.keyAt(i);
+
+            if (key < firstPage || key > lastPage) {
+                adapter.destroyItem(container, key, pages.get(key));
+                pages.remove(key);
+            }
+        }
+
+        for (int key = firstPage; key <= lastPage; key++) {
+            if (pages.get(key) == null) {
+                pages.put(key, adapter.instantiateItem(container, key));
+            }
+        }
+
+        adapter.setPrimaryItem(container, page, pages.get(page));
+    }
+
+    public int getOffscreenPageLimit() {
+        return offscreenPageLimit;
+    }
+
+    public void setOffscreenPageLimit(int offscreenPageLimit) {
+        this.offscreenPageLimit = offscreenPageLimit;
+    }
+}

conductor-modules/viewpager/src/test/java/com/bluelinelabs/conductor/support/util/TestController.java

@@ -0,0 +1,18 @@
+package com.bluelinelabs.conductor.support.util;
+
+import androidx.annotation.NonNull;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.FrameLayout;
+
+import com.bluelinelabs.conductor.Controller;
+
+public class TestController extends Controller {
+
+    @Override @NonNull
+    protected View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
+        return new FrameLayout(inflater.getContext());
+    }
+
+}

conductor-support/gradle.properties

@@ -1,3 +0,0 @@
-POM_NAME=Conductor Support Extensions
-POM_ARTIFACT_ID=conductor-support
-POM_PACKAGING=aar

conductor-support/src/main/java/com/bluelinelabs/conductor/support/ControllerPagerAdapter.java

@@ -1,142 +0,0 @@
-package com.bluelinelabs.conductor.support;
-
-import android.os.Bundle;
-import android.os.Parcelable;
-import android.support.annotation.Nullable;
-import android.support.v4.view.PagerAdapter;
-import android.util.SparseArray;
-import android.view.View;
-import android.view.ViewGroup;
-
-import com.bluelinelabs.conductor.Controller;
-import com.bluelinelabs.conductor.Router;
-import com.bluelinelabs.conductor.RouterTransaction;
-
-/**
- * An adapter for ViewPagers that will handle adding and removing Controllers
- */
-public abstract class ControllerPagerAdapter extends PagerAdapter {
-
-    private static final String KEY_SAVED_PAGES = "ControllerPagerAdapter.savedStates";
-    private static final String KEY_SAVES_STATE = "ControllerPagerAdapter.savesState";
-    private static final String KEY_VISIBLE_PAGE_IDS_KEYS = "ControllerPagerAdapter.visiblePageIds.keys";
-    private static final String KEY_VISIBLE_PAGE_IDS_VALUES = "ControllerPagerAdapter.visiblePageIds.values";
-
-    private final Controller host;
-    private boolean savesState;
-    private SparseArray<Bundle> savedPages = new SparseArray<>();
-    private SparseArray<String> visiblePageIds = new SparseArray<>();
-
-    /**
-     * Creates a new ControllerPagerAdapter using the passed host.
-     */
-    public ControllerPagerAdapter(Controller host, boolean saveControllerState) {
-        this.host = host;
-        savesState = saveControllerState;
-    }
-
-    /**
-     * Return the Controller associated with a specified position.
-     */
-    public abstract Controller getItem(int position);
-
-    @Override
-    public Object instantiateItem(ViewGroup container, int position) {
-        final String name = makeControllerName(container.getId(), getItemId(position));
-
-        Router router = host.getChildRouter(container, name);
-        if (savesState && !router.hasRootController()) {
-            Bundle routerSavedState = savedPages.get(position);
-
-            if (routerSavedState != null) {
-                router.restoreInstanceState(routerSavedState);
-            }
-        }
-
-        if (!router.hasRootController()) {
-            Controller controller = getItem(position);
-            router.setRoot(RouterTransaction.with(controller).tag(name));
-            visiblePageIds.put(position, controller.getInstanceId());
-        } else {
-            router.rebindIfNeeded();
-        }
-
-        return router.getControllerWithTag(name);
-    }
-
-    @Override
-    public void destroyItem(ViewGroup container, int position, Object object) {
-        Router router = ((Controller)object).getRouter();
-
-        if (savesState) {
-            Bundle savedState = new Bundle();
-            router.saveInstanceState(savedState);
-            savedPages.put(position, savedState);
-        }
-
-        visiblePageIds.remove(position);
-
-        host.removeChildRouter(router);
-    }
-
-    @Override
-    public boolean isViewFromObject(View view, Object object) {
-        return ((Controller)object).getView() == view;
-    }
-
-    @Override
-    public Parcelable saveState() {
-        Bundle bundle = new Bundle();
-        bundle.putBoolean(KEY_SAVES_STATE, savesState);
-        bundle.putSparseParcelableArray(KEY_SAVED_PAGES, savedPages);
-
-        int[] visiblePageIdsKeys = new int[visiblePageIds.size()];
-        String[] visiblePageIdsValues = new String[visiblePageIds.size()];
-        for (int i = 0; i < visiblePageIds.size(); i++) {
-            visiblePageIdsKeys[i] = visiblePageIds.keyAt(i);
-            visiblePageIdsValues[i] = visiblePageIds.valueAt(i);
-        }
-        bundle.putIntArray(KEY_VISIBLE_PAGE_IDS_KEYS, visiblePageIdsKeys);
-        bundle.putStringArray(KEY_VISIBLE_PAGE_IDS_VALUES, visiblePageIdsValues);
-
-        return bundle;
-    }
-
-    @Override
-    public void restoreState(Parcelable state, ClassLoader loader) {
-        Bundle bundle = (Bundle)state;
-        if (state != null) {
-            savesState = bundle.getBoolean(KEY_SAVES_STATE, false);
-            savedPages = bundle.getSparseParcelableArray(KEY_SAVED_PAGES);
-
-            int[] visiblePageIdsKeys = bundle.getIntArray(KEY_VISIBLE_PAGE_IDS_KEYS);
-            String[] visiblePageIdsValues = bundle.getStringArray(KEY_VISIBLE_PAGE_IDS_VALUES);
-            visiblePageIds = new SparseArray<>(visiblePageIdsKeys.length);
-            for (int i = 0; i < visiblePageIdsKeys.length; i++) {
-                visiblePageIds.put(visiblePageIdsKeys[i], visiblePageIdsValues[i]);
-            }
-        }
-    }
-
-    /**
-     * Returns the already instantiated Controller in the specified position, if available.
-     */
-    @Nullable
-    public Controller getController(int position) {
-        String instanceId = visiblePageIds.get(position);
-        if (instanceId != null) {
-            return host.getRouter().getControllerWithInstanceId(instanceId);
-        } else {
-            return null;
-        }
-    }
-
-    public long getItemId(int position) {
-        return position;
-    }
-
-    private static String makeControllerName(int viewId, long id) {
-        return viewId + ":" + id;
-    }
-
-}

conductor-support/src/main/java/com/bluelinelabs/conductor/support/RouterPagerAdapter.java

@@ -1,119 +0,0 @@
-package com.bluelinelabs.conductor.support;
-
-import android.os.Bundle;
-import android.os.Parcelable;
-import android.support.annotation.Nullable;
-import android.support.v4.view.PagerAdapter;
-import android.util.SparseArray;
-import android.view.View;
-import android.view.ViewGroup;
-
-import com.bluelinelabs.conductor.Controller;
-import com.bluelinelabs.conductor.Router;
-import com.bluelinelabs.conductor.RouterTransaction;
-
-import java.util.List;
-
-/**
- * An adapter for ViewPagers that uses Routers as pages
- */
-public abstract class RouterPagerAdapter extends PagerAdapter {
-
-    private static final String KEY_SAVED_PAGES = "RouterPagerAdapter.savedStates";
-
-    private final Controller host;
-    private SparseArray<Bundle> savedPages = new SparseArray<>();
-    private SparseArray<Router> visibleRouters = new SparseArray<>();
-
-    /**
-     * Creates a new RouterPagerAdapter using the passed host.
-     */
-    public RouterPagerAdapter(Controller host) {
-        this.host = host;
-    }
-
-    /**
-     * Called when a router is instantiated. Here the router's root should be set if needed.
-     *
-     * @param router   The router used for the page
-     * @param position The page position to be instantiated.
-     */
-    public abstract void configureRouter(Router router, int position);
-
-    @Override
-    public Object instantiateItem(ViewGroup container, int position) {
-        final String name = makeRouterName(container.getId(), getItemId(position));
-
-        Router router = host.getChildRouter(container, name);
-        if (!router.hasRootController()) {
-            Bundle routerSavedState = savedPages.get(position);
-
-            if (routerSavedState != null) {
-                router.restoreInstanceState(routerSavedState);
-            }
-        }
-
-        router.rebindIfNeeded();
-        configureRouter(router, position);
-
-        visibleRouters.put(position, router);
-        return router;
-    }
-
-    @Override
-    public void destroyItem(ViewGroup container, int position, Object object) {
-        Router router = (Router)object;
-
-        Bundle savedState = new Bundle();
-        router.saveInstanceState(savedState);
-        savedPages.put(position, savedState);
-
-        host.removeChildRouter(router);
-
-        visibleRouters.remove(position);
-    }
-
-    @Override
-    public boolean isViewFromObject(View view, Object object) {
-        Router router = (Router)object;
-        final List<RouterTransaction> backstack = router.getBackstack();
-        for (RouterTransaction transaction : backstack) {
-            if (transaction.controller().getView() == view) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    @Override
-    public Parcelable saveState() {
-        Bundle bundle = new Bundle();
-        bundle.putSparseParcelableArray(KEY_SAVED_PAGES, savedPages);
-        return bundle;
-    }
-
-    @Override
-    public void restoreState(Parcelable state, ClassLoader loader) {
-        Bundle bundle = (Bundle)state;
-        if (state != null) {
-            savedPages = bundle.getSparseParcelableArray(KEY_SAVED_PAGES);
-        }
-    }
-
-    /**
-     * Returns the already instantiated Router in the specified position, if available.
-     */
-    @Nullable
-    public Router getRouter(int position) {
-        return visibleRouters.get(position);
-    }
-
-    public long getItemId(int position) {
-        return position;
-    }
-
-    private static String makeRouterName(int viewId, long id) {
-        return viewId + ":" + id;
-    }
-
-}

conductor/build.gradle

@@ -3,7 +3,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'de.mobilej.unmock:UnMockPlugin:0.3.6'
+        classpath 'de.mobilej.unmock:UnMockPlugin:0.6.5'
     }
 }
 
@@ -12,7 +12,6 @@ apply plugin: 'de.mobilej.unmock'
 
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion rootProject.ext.buildToolsVersion
 
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_1_7
@@ -33,22 +32,14 @@ configurations {
 }
 
 dependencies {
-    testCompile rootProject.ext.junit
-    testCompile rootProject.ext.roboelectric
+    testImplementation rootProject.ext.junit
+    testImplementation rootProject.ext.roboelectric
 
-    compile rootProject.ext.supportAnnotations
+    api rootProject.ext.androidxAnnotations
 
     lintChecks project(path: ':conductor-lint', configuration: 'lintChecks')
 }
 
-unMock {
-    downloadFrom 'https://oss.sonatype.org/content/groups/public/org/robolectric/android-all/4.3_r2-robolectric-0/android-all-4.3_r2-robolectric-0.jar'
-
-    keep "android.os.Bundle"
-    keep "android.os.BaseBundle"
-    keep "android.text.TextUtils"
-}
-
 task copyLintJar(type: Copy) {
     from(configurations.lintChecks) {
         rename { 'lint.jar' }

conductor/proguard-rules.txt

@@ -2,4 +2,7 @@
 -keepclassmembers public class * extends com.bluelinelabs.conductor.Controller {
    public <init>();
    public <init>(android.os.Bundle);
-}
+}
+-keepclassmembers public class * extends com.bluelinelabs.conductor.ControllerChangeHandler {
+   public <init>();
+}

conductor/src/main/AndroidManifest.xml

@@ -1,3 +1,3 @@
 <manifest package="com.bluelinelabs.conductor">
     <application />
-</manifest>
+</manifest>

conductor/src/main/java/com/bluelinelabs/conductor/ActivityHostedRouter.java

@@ -2,19 +2,23 @@ package com.bluelinelabs.conductor;
 
 import android.app.Activity;
 import android.content.Intent;
+import android.content.IntentSender;
+import android.content.IntentSender.SendIntentException;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
 import com.bluelinelabs.conductor.internal.LifecycleHandler;
+import com.bluelinelabs.conductor.internal.TransactionIndexer;
 
 import java.util.List;
 
 public class ActivityHostedRouter extends Router {
 
     private LifecycleHandler lifecycleHandler;
+    private final TransactionIndexer transactionIndexer = new TransactionIndexer();
 
     public final void setHost(@NonNull LifecycleHandler lifecycleHandler, @NonNull ViewGroup container) {
         if (this.lifecycleHandler != lifecycleHandler || this.container != container) {
@@ -28,9 +32,25 @@ public class ActivityHostedRouter extends Router {
 
             this.lifecycleHandler = lifecycleHandler;
             this.container = container;
+
+            watchContainerAttach();
         }
     }
 
+    @Override
+    public void saveInstanceState(@NonNull Bundle outState) {
+        super.saveInstanceState(outState);
+
+        transactionIndexer.saveInstanceState(outState);
+    }
+
+    @Override
+    public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
+        super.restoreInstanceState(savedInstanceState);
+
+        transactionIndexer.restoreInstanceState(savedInstanceState);
+    }
+
     @Override @Nullable
     public Activity getActivity() {
         return lifecycleHandler != null ? lifecycleHandler.getLifecycleActivity() : null;
@@ -69,6 +89,12 @@ public class ActivityHostedRouter extends Router {
         lifecycleHandler.startActivityForResult(instanceId, intent, requestCode, options);
     }
 
+    @Override
+    void startIntentSenderForResult(@NonNull String instanceId, @NonNull IntentSender intent, int requestCode, @Nullable Intent fillInIntent,
+                                    int flagsMask, int flagsValues, int extraFlags, @Nullable Bundle options) throws SendIntentException {
+        lifecycleHandler.startIntentSenderForResult(instanceId, intent, requestCode, fillInIntent, flagsMask, flagsValues, extraFlags, options);
+    }
+
     @Override
     void registerForActivityResult(@NonNull String instanceId, int requestCode) {
         lifecycleHandler.registerForActivityResult(instanceId, requestCode);
@@ -98,4 +124,15 @@ public class ActivityHostedRouter extends Router {
     Router getRootRouter() {
         return this;
     }
+
+    @Override @NonNull
+    TransactionIndexer getTransactionIndexer() {
+        return transactionIndexer;
+    }
+
+    @Override
+    public void onContextAvailable() {
+        super.onContextAvailable();
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/Backstack.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import java.util.ArrayDeque;
 import java.util.ArrayList;
@@ -18,16 +18,16 @@ class Backstack implements Iterable<RouterTransaction> {
     private final Deque<RouterTransaction> backstack = new ArrayDeque<>();
 
     @SuppressWarnings("BooleanMethodIsAlwaysInverted")
-    public boolean isEmpty() {
+    boolean isEmpty() {
         return backstack.isEmpty();
     }
 
-    public int size() {
+    int size() {
         return backstack.size();
     }
 
     @Nullable
-    public RouterTransaction root() {
+    RouterTransaction root() {
         return backstack.size() > 0 ? backstack.getLast() : null;
     }
 
@@ -37,12 +37,12 @@ class Backstack implements Iterable<RouterTransaction> {
     }
 
     @NonNull
-    public Iterator<RouterTransaction> reverseIterator() {
+    Iterator<RouterTransaction> reverseIterator() {
         return backstack.descendingIterator();
     }
 
     @NonNull
-    public List<RouterTransaction> popTo(@NonNull RouterTransaction transaction) {
+    List<RouterTransaction> popTo(@NonNull RouterTransaction transaction) {
         List<RouterTransaction> popped = new ArrayList<>();
         if (backstack.contains(transaction)) {
             while (backstack.peek() != transaction) {
@@ -56,27 +56,23 @@ class Backstack implements Iterable<RouterTransaction> {
     }
 
     @NonNull
-    public RouterTransaction pop() {
+    RouterTransaction pop() {
         RouterTransaction popped = backstack.pop();
         popped.controller.destroy();
         return popped;
     }
 
     @Nullable
-    public RouterTransaction peek() {
+    RouterTransaction peek() {
         return backstack.peek();
     }
 
-    public void remove(@NonNull RouterTransaction transaction) {
-        backstack.removeFirstOccurrence(transaction);
-    }
-
-    public void push(@NonNull RouterTransaction transaction) {
+    void push(@NonNull RouterTransaction transaction) {
         backstack.push(transaction);
     }
 
     @NonNull
-    public List<RouterTransaction> popAll() {
+    List<RouterTransaction> popAll() {
         List<RouterTransaction> list = new ArrayList<>();
         while (!isEmpty()) {
             list.add(pop());
@@ -84,28 +80,23 @@ class Backstack implements Iterable<RouterTransaction> {
         return list;
     }
 
-    public void setBackstack(@NonNull List<RouterTransaction> backstack) {
-        for (RouterTransaction existingTransaction : this.backstack) {
-            boolean contains = false;
-            for (RouterTransaction newTransaction : backstack) {
-                if (existingTransaction.controller == newTransaction.controller) {
-                    contains = true;
-                    break;
-                }
-            }
-
-            if (!contains) {
-                existingTransaction.controller.destroy();
-            }
-        }
-
+    void setBackstack(@NonNull List<RouterTransaction> backstack) {
         this.backstack.clear();
         for (RouterTransaction transaction : backstack) {
             this.backstack.push(transaction);
         }
     }
 
-    public void saveInstanceState(@NonNull Bundle outState) {
+    boolean contains(@NonNull Controller controller) {
+        for (RouterTransaction transaction : backstack) {
+            if (controller == transaction.controller) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    void saveInstanceState(@NonNull Bundle outState) {
         ArrayList<Bundle> entryBundles = new ArrayList<>(backstack.size());
         for (RouterTransaction entry : backstack) {
             entryBundles.add(entry.saveInstanceState());
@@ -114,7 +105,7 @@ class Backstack implements Iterable<RouterTransaction> {
         outState.putParcelableArrayList(KEY_ENTRIES, entryBundles);
     }
 
-    public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
+    void restoreInstanceState(@NonNull Bundle savedInstanceState) {
         ArrayList<Bundle> entryBundles = savedInstanceState.getParcelableArrayList(KEY_ENTRIES);
         if (entryBundles != null) {
             Collections.reverse(entryBundles);

conductor/src/main/java/com/bluelinelabs/conductor/ChangeHandlerFrameLayout.java

@@ -3,8 +3,8 @@ package com.bluelinelabs.conductor;
 import android.annotation.TargetApi;
 import android.content.Context;
 import android.os.Build;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.ViewGroup;

conductor/src/main/java/com/bluelinelabs/conductor/Conductor.java

@@ -2,20 +2,21 @@ package com.bluelinelabs.conductor;
 
 import android.app.Activity;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.support.annotation.UiThread;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.internal.LifecycleHandler;
+import com.bluelinelabs.conductor.internal.ThreadUtils;
 
 /**
  * Point of initial interaction with Conductor. Used to attach a {@link Router} to your Activity.
  */
 public final class Conductor {
-    
+
     private Conductor() {}
-    
+
     /**
      * Conductor will create a {@link Router} that has been initialized for your Activity and containing ViewGroup.
      * If an existing {@link Router} is already associated with this Activity/ViewGroup pair, either in memory
@@ -30,6 +31,8 @@ public final class Conductor {
      */
     @NonNull @UiThread
     public static Router attachRouter(@NonNull Activity activity, @NonNull ViewGroup container, @Nullable Bundle savedInstanceState) {
+        ThreadUtils.ensureMainThread();
+
         LifecycleHandler lifecycleHandler = LifecycleHandler.install(activity);
 
         Router router = lifecycleHandler.getRouter(container, savedInstanceState);

conductor/src/main/java/com/bluelinelabs/conductor/Controller.java

@@ -4,13 +4,11 @@ import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
+import android.content.IntentSender;
 import android.content.res.Resources;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Parcelable;
-import android.support.annotation.IdRes;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
 import android.text.TextUtils;
 import android.util.SparseArray;
 import android.view.LayoutInflater;
@@ -20,7 +18,6 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 
-import com.bluelinelabs.conductor.Router.OnControllerPushedListener;
 import com.bluelinelabs.conductor.internal.ClassUtils;
 import com.bluelinelabs.conductor.internal.RouterRequiringFunc;
 import com.bluelinelabs.conductor.internal.ViewAttachHandler;
@@ -30,10 +27,15 @@ import java.lang.ref.WeakReference;
 import java.lang.reflect.Constructor;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.UUID;
 
+import androidx.annotation.IdRes;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 /**
  * A Controller manages portions of the UI. It is similar to an Activity or Fragment in that it manages its
  * own lifecycle and controls interactions between the UI and whatever logic is required. It is, however,
@@ -45,7 +47,6 @@ public abstract class Controller {
     private static final String KEY_CLASS_NAME = "Controller.className";
     private static final String KEY_VIEW_STATE = "Controller.viewState";
     private static final String KEY_CHILD_ROUTERS = "Controller.childRouters";
-    private static final String KEY_CHILD_BACKSTACK = "Controller.childBackstack";
     private static final String KEY_SAVED_STATE = "Controller.savedState";
     private static final String KEY_INSTANCE_ID = "Controller.instanceId";
     private static final String KEY_TARGET_INSTANCE_ID = "Controller.target.instanceId";
@@ -55,29 +56,30 @@ public abstract class Controller {
     private static final String KEY_OVERRIDDEN_PUSH_HANDLER = "Controller.overriddenPushHandler";
     private static final String KEY_OVERRIDDEN_POP_HANDLER = "Controller.overriddenPopHandler";
     private static final String KEY_VIEW_STATE_HIERARCHY = "Controller.viewState.hierarchy";
-    private static final String KEY_VIEW_STATE_BUNDLE = "Controller.viewState.bundle";
+    static final String KEY_VIEW_STATE_BUNDLE = "Controller.viewState.bundle";
     private static final String KEY_RETAIN_VIEW_MODE = "Controller.retainViewMode";
 
     private final Bundle args;
 
     Bundle viewState;
     private Bundle savedInstanceState;
-    private boolean isBeingDestroyed;
+    boolean isBeingDestroyed;
     private boolean destroyed;
     private boolean attached;
     private boolean hasOptionsMenu;
     private boolean optionsMenuHidden;
-    private boolean viewIsAttached;
-    private boolean viewWasDetached;
-    private Router router;
-    private View view;
+    boolean viewIsAttached;
+    boolean viewWasDetached;
+    Router router;
+    View view;
     private Controller parentController;
-    private String instanceId;
+    String instanceId;
     private String targetInstanceId;
     private boolean needsAttach;
     private boolean attachedToUnownedParent;
+    private boolean awaitingParentAttach;
     private boolean hasSavedViewState;
-    private boolean isDetachFrozen;
+    boolean isDetachFrozen;
     private ControllerChangeHandler overriddenPushHandler;
     private ControllerChangeHandler overriddenPopHandler;
     private RetainViewMode retainViewMode = RetainViewMode.RELEASE_DETACH;
@@ -86,30 +88,35 @@ public abstract class Controller {
     private final List<LifecycleListener> lifecycleListeners = new ArrayList<>();
     private final ArrayList<String> requestedPermissions = new ArrayList<>();
     private final ArrayList<RouterRequiringFunc> onRouterSetListeners = new ArrayList<>();
-    private final List<Controller> childBackstack = new LinkedList<>();
     private WeakReference<View> destroyedView;
-
-    private final OnControllerPushedListener onControllerPushedListener = new OnControllerPushedListener() {
-        @Override
-        public void onControllerPushed(Controller controller) {
-            onChildControllerPushed(controller);
-        }
-    };
+    private boolean isPerformingExitTransition;
+    private boolean isContextAvailable;
 
     @NonNull
     static Controller newInstance(@NonNull Bundle bundle) {
         final String className = bundle.getString(KEY_CLASS_NAME);
         //noinspection ConstantConditions
-        Constructor[] constructors = ClassUtils.classForName(className, false).getConstructors();
+        Class cls = ClassUtils.classForName(className, false);
+        Constructor[] constructors = cls.getConstructors();
         Constructor bundleConstructor = getBundleConstructor(constructors);
 
+        Bundle args = bundle.getBundle(KEY_ARGS);
+        if (args != null) {
+            args.setClassLoader(cls.getClassLoader());
+        }
+
         Controller controller;
         try {
             if (bundleConstructor != null) {
-                controller = (Controller)bundleConstructor.newInstance(bundle.getBundle(KEY_ARGS));
+                controller = (Controller)bundleConstructor.newInstance(args);
             } else {
                 //noinspection ConstantConditions
                 controller = (Controller)getDefaultConstructor(constructors).newInstance();
+
+                // Restore the args that existed before the last process death
+                if (args != null) {
+                    controller.args.putAll(args);
+                }
             }
         } catch (Exception e) {
             throw new RuntimeException("An exception occurred while creating a new instance of " + className + ". " + e.getMessage(), e);
@@ -132,7 +139,7 @@ public abstract class Controller {
      * @param args Any arguments that need to be retained.
      */
     protected Controller(@Nullable Bundle args) {
-        this.args = args != null ? args : new Bundle();
+        this.args = args != null ? args : new Bundle(getClass().getClassLoader());
         instanceId = UUID.randomUUID().toString();
         ensureRequiredConstructor();
     }
@@ -183,7 +190,7 @@ public abstract class Controller {
      * the same container unless you have a great reason to do so (ex: ViewPagers).
      *
      * @param container The ViewGroup that hosts the child Router
-     * @param tag The router's tag
+     * @param tag The router's tag or {@code null} if none is needed
      */
     @NonNull
     public final Router getChildRouter(@NonNull ViewGroup container, @Nullable String tag) {
@@ -195,10 +202,12 @@ public abstract class Controller {
      * Retrieves the child {@link Router} for the given container/tag combination. Note that multiple
      * routers should not exist in the same container unless a lot of care is taken to maintain order
      * between them. Avoid using the same container unless you have a great reason to do so (ex: ViewPagers).
+     * The only time this method will return {@code null} is when the child router does not exist prior
+     * to calling this method and the createIfNeeded parameter is set to false.
      *
      * @param container The ViewGroup that hosts the child Router
-     * @param tag The router's tag
-     * @param createIfNeeded If true, a router will be created if one does not yet exist. Else false will be returned in this case.
+     * @param tag The router's tag or {@code null} if none is needed
+     * @param createIfNeeded If true, a router will be created if one does not yet exist. Else {@code null} will be returned in this case.
      */
     @Nullable
     public final Router getChildRouter(@NonNull ViewGroup container, @Nullable String tag, boolean createIfNeeded) {
@@ -215,19 +224,27 @@ public abstract class Controller {
         if (childRouter == null) {
             if (createIfNeeded) {
                 childRouter = new ControllerHostedRouter(container.getId(), tag);
-                monitorChildRouter(childRouter);
                 childRouter.setHost(this, container);
                 childRouters.add(childRouter);
+
+                if (isPerformingExitTransition) {
+                    childRouter.setDetachFrozen(true);
+                }
             }
         } else if (!childRouter.hasHost()) {
             childRouter.setHost(this, container);
-            monitorChildRouter(childRouter);
             childRouter.rebindIfNeeded();
         }
 
         return childRouter;
     }
 
+    /**
+     * Removes a child {@link Router} from this Controller. When removed, all Controllers currently managed by
+     * the {@link Router} will be destroyed.
+     *
+     * @param childRouter The router to be removed
+     */
     public final void removeChildRouter(@NonNull Router childRouter) {
         if ((childRouter instanceof ControllerHostedRouter) && childRouters.remove(childRouter)) {
             childRouter.destroy(true);
@@ -256,7 +273,8 @@ public abstract class Controller {
     }
 
     /**
-     * Return this Controller's View, if available.
+     * Return this Controller's View or {@code null} if it has not yet been created or has been
+     * destroyed.
      */
     @Nullable
     public final View getView() {
@@ -264,15 +282,17 @@ public abstract class Controller {
     }
 
     /**
-     * Returns the host Activity of this Controller's {@link Router}
+     * Returns the host Activity of this Controller's {@link Router} or {@code null} if this
+     * Controller has not yet been attached to an Activity or if the Activity has been destroyed.
      */
     @Nullable
     public final Activity getActivity() {
-        return router.getActivity();
+        return router != null ? router.getActivity() : null;
     }
 
     /**
-     * Returns the Resources from the host Activity
+     * Returns the Resources from the host Activity or {@code null} if this Controller has not
+     * yet been attached to an Activity or if the Activity has been destroyed.
      */
     @Nullable
     public final Resources getResources() {
@@ -281,7 +301,8 @@ public abstract class Controller {
     }
 
     /**
-     * Returns the Application Context derived from the host Activity
+     * Returns the Application Context derived from the host Activity or {@code null} if this Controller
+     * has not yet been attached to an Activity or if the Activity has been destroyed.
      */
     @Nullable
     public final Context getApplicationContext() {
@@ -290,7 +311,8 @@ public abstract class Controller {
     }
 
     /**
-     * Returns this Controller's parent Controller if it is a child Controller.
+     * Returns this Controller's parent Controller if it is a child Controller or {@code null} if
+     * it has no parent.
      */
     @Nullable
     public final Controller getParentController() {
@@ -307,10 +329,10 @@ public abstract class Controller {
     }
 
     /**
-     * Returns the Controller with the given instance id, if available.
-     * May return the controller itself or a matching descendant
+     * Returns the Controller with the given instance id or {@code null} if no such Controller
+     * exists. May return the Controller itself or a matching descendant
+     *
      * @param instanceId The instance ID being searched for
-     * @return The matching Controller, if one exists
      */
     @Nullable
     final Controller findController(@NonNull String instanceId) {
@@ -332,10 +354,8 @@ public abstract class Controller {
      */
     @NonNull
     public final List<Router> getChildRouters() {
-        List<Router> routers = new ArrayList<>();
-        for (Router router : childRouters) {
-            routers.add(router);
-        }
+        List<Router> routers = new ArrayList<>(childRouters.size());
+        routers.addAll(childRouters);
         return routers;
     }
 
@@ -355,7 +375,8 @@ public abstract class Controller {
     }
 
     /**
-     * Returns the target Controller that was set with the {@link #setTargetController(Controller)} method
+     * Returns the target Controller that was set with the {@link #setTargetController(Controller)}
+     * method or {@code null} if this Controller has no target.
      *
      * @return This Controller's target
      */
@@ -391,6 +412,19 @@ public abstract class Controller {
      */
     protected void onChangeEnded(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) { }
 
+    /**
+     * Called when this Controller has a Context available to it. This will happen very early on in the lifecycle
+     * (before a view is created). If the host activity is re-created (ex: for orientation change), this will be
+     * called again when the new context is available.
+     */
+    protected void onContextAvailable(@NonNull Context context) { }
+
+    /**
+     * Called when this Controller's Context is no longer available. This can happen when the Controller is
+     * destroyed or when the host Activity is destroyed.
+     */
+    protected void onContextUnavailable() { }
+
     /**
      * Called when this Controller is attached to its host ViewGroup
      *
@@ -491,6 +525,14 @@ public abstract class Controller {
         });
     }
 
+    /**
+     * Calls startIntentSenderForResult(IntentSender, int, Intent, int, int, int, Bundle) from this Controller's host Activity.
+     */
+    public final void startIntentSenderForResult(@NonNull final IntentSender intent, final int requestCode, @Nullable final Intent fillInIntent, final int flagsMask,
+                                                 final int flagsValues, final int extraFlags, @Nullable final Bundle options) throws IntentSender.SendIntentException {
+        router.startIntentSenderForResult(instanceId, intent, requestCode, fillInIntent, flagsMask, flagsValues, extraFlags, options);
+    }
+
     /**
      * Registers this Controller to handle onActivityResult responses. Calling this method is NOT
      * necessary when calling {@link #startActivityForResult(Intent, int)}
@@ -534,7 +576,7 @@ public abstract class Controller {
      * @param permission A permission this Controller has requested
      */
     public boolean shouldShowRequestPermissionRationale(@NonNull String permission) {
-        return false;
+        return Build.VERSION.SDK_INT >= 23 && getActivity().shouldShowRequestPermissionRationale(permission);
     }
 
     /**
@@ -552,8 +594,22 @@ public abstract class Controller {
      * @return True if this Controller has consumed the back button press, otherwise false
      */
     public boolean handleBack() {
-        for (int i = childBackstack.size() - 1; i >= 0; i--) {
-            Controller childController = childBackstack.get(i);
+        List<RouterTransaction> childTransactions = new ArrayList<>();
+
+        for (ControllerHostedRouter childRouter : childRouters) {
+            childTransactions.addAll(childRouter.getBackstack());
+        }
+
+        Collections.sort(childTransactions, new Comparator<RouterTransaction>() {
+            @Override
+            public int compare(RouterTransaction o1, RouterTransaction o2) {
+                return o2.transactionIndex - o1.transactionIndex;
+            }
+        });
+
+        for (RouterTransaction transaction : childTransactions) {
+            Controller childController = transaction.controller;
+
             if (childController.isAttached() && childController.getRouter().handleBack()) {
                 return true;
             }
@@ -567,7 +623,7 @@ public abstract class Controller {
      *
      * @param lifecycleListener The listener
      */
-    public void addLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
+    public final void addLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
         if (!lifecycleListeners.contains(lifecycleListener)) {
             lifecycleListeners.add(lifecycleListener);
         }
@@ -578,7 +634,7 @@ public abstract class Controller {
      *
      * @param lifecycleListener The listener to be removed
      */
-    public void removeLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
+    public final void removeLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
         lifecycleListeners.remove(lifecycleListener);
     }
 
@@ -695,8 +751,8 @@ public abstract class Controller {
         return false;
     }
 
-    final void setNeedsAttach() {
-        needsAttach = true;
+    final void setNeedsAttach(boolean needsAttach) {
+        this.needsAttach = needsAttach;
     }
 
     final void prepareForHostDetach() {
@@ -735,6 +791,29 @@ public abstract class Controller {
         }
     }
 
+    final void onContextAvailable() {
+        final Context context = router.getActivity();
+
+        if (context != null && !isContextAvailable) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.preContextAvailable(this);
+            }
+
+            isContextAvailable = true;
+            onContextAvailable(context);
+
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.postContextAvailable(this, context);
+            }
+        }
+
+        for (Router childRouter : childRouters) {
+            childRouter.onContextAvailable();
+        }
+    }
+
     final void executeWithRouter(@NonNull RouterRequiringFunc listener) {
         if (router != null) {
             listener.execute();
@@ -744,6 +823,10 @@ public abstract class Controller {
     }
 
     final void activityStarted(@NonNull Activity activity) {
+        if (viewAttachHandler != null) {
+            viewAttachHandler.onActivityStarted();
+        }
+
         onActivityStarted(activity);
     }
 
@@ -763,23 +846,55 @@ public abstract class Controller {
     }
 
     final void activityStopped(@NonNull Activity activity) {
+        final boolean attached = this.attached;
+
+        if (viewAttachHandler != null) {
+            viewAttachHandler.onActivityStopped();
+        }
+
+        if (attached && activity.isChangingConfigurations()) {
+            needsAttach = true;
+        }
+
         onActivityStopped(activity);
     }
 
-    final void activityDestroyed(boolean isChangingConfigurations) {
-        if (isChangingConfigurations) {
-            detach(view, true);
+    final void activityDestroyed(@NonNull Activity activity) {
+        if (activity.isChangingConfigurations()) {
+            detach(view, true, false);
         } else {
             destroy(true);
         }
+
+        if (isContextAvailable) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.preContextUnavailable(this, activity);
+            }
+
+            isContextAvailable = false;
+            onContextUnavailable();
+
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.postContextUnavailable(this);
+            }
+        }
     }
 
-    private void attach(@NonNull View view) {
+    void attach(@NonNull View view) {
         attachedToUnownedParent = router == null || view.getParent() != router.container;
-        if (attachedToUnownedParent) {
+        if (attachedToUnownedParent || isBeingDestroyed) {
             return;
         }
 
+        if (parentController != null && !parentController.attached) {
+            awaitingParentAttach = true;
+            return;
+        } else {
+            awaitingParentAttach = false;
+        }
+
         hasSavedViewState = false;
 
         List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
@@ -788,7 +903,7 @@ public abstract class Controller {
         }
 
         attached = true;
-        needsAttach = false;
+        needsAttach = router.isActivityStopped;
 
         onAttach(view);
 
@@ -798,18 +913,26 @@ public abstract class Controller {
 
         listeners = new ArrayList<>(lifecycleListeners);
         for (LifecycleListener lifecycleListener : listeners) {
-            lifecycleListener.postAttach(this, view);
+            lifecycleListener.postAttach(Controller.this, view);
+        }
+
+        for (ControllerHostedRouter childRouter : childRouters) {
+            for (RouterTransaction childTransaction : childRouter.backstack) {
+                if (childTransaction.controller.awaitingParentAttach) {
+                    childTransaction.controller.attach(childTransaction.controller.view);
+                }
+            }
         }
     }
 
-    void detach(@NonNull View view, boolean forceViewRefRemoval) {
+    void detach(@NonNull View view, boolean forceViewRefRemoval, boolean blockViewRefRemoval) {
         if (!attachedToUnownedParent) {
             for (ControllerHostedRouter router : childRouters) {
                 router.prepareForHostDetach();
             }
         }
 
-        final boolean removeViewRef = forceViewRefRemoval || retainViewMode == RetainViewMode.RELEASE_DETACH || isBeingDestroyed;
+        final boolean removeViewRef = !blockViewRefRemoval && (forceViewRefRemoval || retainViewMode == RetainViewMode.RELEASE_DETACH || isBeingDestroyed);
 
         if (attached) {
             List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
@@ -818,7 +941,10 @@ public abstract class Controller {
             }
 
             attached = false;
-            onDetach(view);
+
+            if (!awaitingParentAttach) {
+                onDetach(view);
+            }
 
             if (hasOptionsMenu && !optionsMenuHidden) {
                 router.invalidateOptionsMenu();
@@ -874,7 +1000,7 @@ public abstract class Controller {
 
     final View inflate(@NonNull ViewGroup parent) {
         if (view != null && view.getParent() != null && view.getParent() != parent) {
-            detach(view, true);
+            detach(view, true, false);
             removeViewReference();
         }
 
@@ -898,21 +1024,26 @@ public abstract class Controller {
 
             viewAttachHandler = new ViewAttachHandler(new ViewAttachListener() {
                 @Override
-                public void onAttached(View v) {
-                    if (v == view) {
-                        viewIsAttached = true;
-                        viewWasDetached = false;
-                    }
-                    attach(v);
+                public void onAttached() {
+                    viewIsAttached = true;
+                    viewWasDetached = false;
+                    attach(view);
                 }
 
                 @Override
-                public void onDetached(View v) {
+                public void onDetached(boolean fromActivityStop) {
                     viewIsAttached = false;
                     viewWasDetached = true;
 
                     if (!isDetachFrozen) {
-                        detach(v, false);
+                        detach(view, false, fromActivityStop);
+                    }
+                }
+
+                @Override
+                public void onViewDetachAfterStop() {
+                    if (!isDetachFrozen) {
+                        detach(view, false, false);
                     }
                 }
             });
@@ -931,7 +1062,6 @@ public abstract class Controller {
 
                 if (containerView != null && containerView instanceof ViewGroup) {
                     childRouter.setHost(this, (ViewGroup)containerView);
-                    monitorChildRouter(childRouter);
                     childRouter.rebindIfNeeded();
                 }
             }
@@ -939,6 +1069,21 @@ public abstract class Controller {
     }
 
     private void performDestroy() {
+        if (isContextAvailable) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.preContextUnavailable(this, getActivity());
+            }
+
+            isContextAvailable = false;
+            onContextUnavailable();
+
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
+                lifecycleListener.postContextUnavailable(this);
+            }
+        }
+
         if (!destroyed) {
             List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
             for (LifecycleListener lifecycleListener : listeners) {
@@ -976,7 +1121,7 @@ public abstract class Controller {
         if (!attached) {
             removeViewReference();
         } else if (removeViews) {
-            detach(view, true);
+            detach(view, true, false);
         }
     }
 
@@ -989,7 +1134,7 @@ public abstract class Controller {
         view.saveHierarchyState(hierarchyState);
         viewState.putSparseParcelableArray(KEY_VIEW_STATE_HIERARCHY, hierarchyState);
 
-        Bundle stateBundle = new Bundle();
+        Bundle stateBundle = new Bundle(getClass().getClassLoader());
         onSaveViewState(view, stateBundle);
         viewState.putBundle(KEY_VIEW_STATE_BUNDLE, stateBundle);
 
@@ -1002,7 +1147,9 @@ public abstract class Controller {
     private void restoreViewState(@NonNull View view) {
         if (viewState != null) {
             view.restoreHierarchyState(viewState.getSparseParcelableArray(KEY_VIEW_STATE_HIERARCHY));
-            onRestoreViewState(view, viewState.getBundle(KEY_VIEW_STATE_BUNDLE));
+            Bundle savedViewState = viewState.getBundle(KEY_VIEW_STATE_BUNDLE);
+            savedViewState.setClassLoader(getClass().getClassLoader());
+            onRestoreViewState(view, savedViewState);
 
             restoreChildControllerHosts();
 
@@ -1035,7 +1182,7 @@ public abstract class Controller {
             outState.putBundle(KEY_OVERRIDDEN_POP_HANDLER, overriddenPopHandler.toBundle());
         }
 
-        ArrayList<Bundle> childBundles = new ArrayList<>();
+        ArrayList<Bundle> childBundles = new ArrayList<>(childRouters.size());
         for (ControllerHostedRouter childRouter : childRouters) {
             Bundle routerBundle = new Bundle();
             childRouter.saveInstanceState(routerBundle);
@@ -1043,13 +1190,7 @@ public abstract class Controller {
         }
         outState.putParcelableArrayList(KEY_CHILD_ROUTERS, childBundles);
 
-        ArrayList<String> childBackstack = new ArrayList<>();
-        for (Controller controller : this.childBackstack) {
-            childBackstack.add(controller.instanceId);
-        }
-        outState.putStringArrayList(KEY_CHILD_BACKSTACK, childBackstack);
-
-        Bundle savedState = new Bundle();
+        Bundle savedState = new Bundle(getClass().getClassLoader());
         onSaveInstanceState(savedState);
 
         List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
@@ -1080,19 +1221,13 @@ public abstract class Controller {
         for (Bundle childBundle : childBundles) {
             ControllerHostedRouter childRouter = new ControllerHostedRouter();
             childRouter.restoreInstanceState(childBundle);
-            monitorChildRouter(childRouter);
             childRouters.add(childRouter);
         }
 
-        List<String> childBackstackIds = savedInstanceState.getStringArrayList(KEY_CHILD_BACKSTACK);
-        for (String controllerId : childBackstackIds) {
-            Controller childController = findController(controllerId);
-            if (childController != null) {
-                childBackstack.add(childController);
-            }
-        }
-
         this.savedInstanceState = savedInstanceState.getBundle(KEY_SAVED_STATE);
+        if (this.savedInstanceState != null) {
+            this.savedInstanceState.setClassLoader(getClass().getClassLoader());
+        }
         performOnRestoreInstanceState();
     }
 
@@ -1111,6 +1246,7 @@ public abstract class Controller {
 
     final void changeStarted(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
         if (!changeType.isEnter) {
+            isPerformingExitTransition = true;
             for (ControllerHostedRouter router : childRouters) {
                 router.setDetachFrozen(true);
             }
@@ -1126,6 +1262,7 @@ public abstract class Controller {
 
     final void changeEnded(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
         if (!changeType.isEnter) {
+            isPerformingExitTransition = false;
             for (ControllerHostedRouter router : childRouters) {
                 router.setDetachFrozen(false);
             }
@@ -1145,6 +1282,8 @@ public abstract class Controller {
             }
             destroyedView = null;
         }
+
+        changeHandler.onEnd();
     }
 
     final void setDetachFrozen(boolean frozen) {
@@ -1156,7 +1295,7 @@ public abstract class Controller {
             }
 
             if (!frozen && view != null && viewWasDetached) {
-                detach(view, false);
+                detach(view, false, false);
             }
         }
     }
@@ -1177,22 +1316,6 @@ public abstract class Controller {
         return attached && hasOptionsMenu && !optionsMenuHidden && onOptionsItemSelected(item);
     }
 
-    private void monitorChildRouter(@NonNull ControllerHostedRouter childRouter) {
-        childRouter.setOnControllerPushedListener(onControllerPushedListener);
-    }
-
-    private void onChildControllerPushed(@NonNull Controller controller) {
-        if (!childBackstack.contains(controller)) {
-            childBackstack.add(controller);
-            controller.addLifecycleListener(new LifecycleListener() {
-                @Override
-                public void postDestroy(@NonNull Controller controller) {
-                    childBackstack.remove(controller);
-                }
-            });
-        }
-    }
-
     final void setParentController(@Nullable Controller controller) {
         parentController = controller;
     }
@@ -1253,6 +1376,12 @@ public abstract class Controller {
         public void preDestroy(@NonNull Controller controller) { }
         public void postDestroy(@NonNull Controller controller) { }
 
+        public void preContextAvailable(@NonNull Controller controller) { }
+        public void postContextAvailable(@NonNull Controller controller, @NonNull Context context) { }
+
+        public void preContextUnavailable(@NonNull Controller controller, @NonNull Context context) { }
+        public void postContextUnavailable(@NonNull Controller controller) { }
+
         public void onSaveInstanceState(@NonNull Controller controller, @NonNull Bundle outState) { }
         public void onRestoreInstanceState(@NonNull Controller controller, @NonNull Bundle savedInstanceState) { }
 

conductor/src/main/java/com/bluelinelabs/conductor/ControllerChangeHandler.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewParent;
@@ -10,7 +10,6 @@ import android.view.ViewParent;
 import com.bluelinelabs.conductor.changehandler.SimpleSwapChangeHandler;
 import com.bluelinelabs.conductor.internal.ClassUtils;
 
-import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -25,17 +24,17 @@ public abstract class ControllerChangeHandler {
     private static final String KEY_CLASS_NAME = "ControllerChangeHandler.className";
     private static final String KEY_SAVED_STATE = "ControllerChangeHandler.savedState";
 
-    private static final Map<String, ControllerChangeHandler> inProgressPushHandlers = new HashMap<>();
+    static final Map<String, ChangeHandlerData> inProgressChangeHandlers = new HashMap<>();
 
-    private boolean forceRemoveViewOnPush;
+    boolean forceRemoveViewOnPush;
     private boolean hasBeenUsed;
 
     /**
      * Responsible for swapping Views from one Controller to another.
      *
      * @param container      The container these Views are hosted in.
-     * @param from           The previous View in the container, if any.
-     * @param to             The next View that should be put in the container, if any.
+     * @param from           The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to             The next View that should be put in the container or {@code null} if no Controller is being transitioned to
      * @param isPush         True if this is a push transaction, false if it's a pop.
      * @param changeListener This listener must be called when any transitions or animations are completed.
      */
@@ -63,8 +62,9 @@ public abstract class ControllerChangeHandler {
      * Will be called on change handlers that push a controller if the controller being pushed is
      * popped before it has completed.
      *
-     * @param newHandler the change handler that has caused this push to be aborted
-     * @param newTop     the controller that will now be at the top of the backstack
+     * @param newHandler The change handler that has caused this push to be aborted
+     * @param newTop     The Controller that will now be at the top of the backstack or {@code null}
+     *                   if there will be no new Controller at the top
      */
     public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) { }
 
@@ -127,33 +127,34 @@ public abstract class ControllerChangeHandler {
         }
     }
 
-    static boolean completePushImmediately(@NonNull String controllerInstanceId) {
-        ControllerChangeHandler changeHandler = inProgressPushHandlers.get(controllerInstanceId);
-        if (changeHandler != null) {
-            changeHandler.completeImmediately();
-            inProgressPushHandlers.remove(controllerInstanceId);
+    static boolean completeHandlerImmediately(@NonNull String controllerInstanceId) {
+        ChangeHandlerData changeHandlerData = inProgressChangeHandlers.get(controllerInstanceId);
+        if (changeHandlerData != null) {
+            changeHandlerData.changeHandler.completeImmediately();
+            inProgressChangeHandlers.remove(controllerInstanceId);
             return true;
         }
         return false;
     }
 
-    public static void abortPush(@NonNull Controller toAbort, @Nullable Controller newController, @NonNull ControllerChangeHandler newChangeHandler) {
-        ControllerChangeHandler handlerForPush = inProgressPushHandlers.get(toAbort.getInstanceId());
-        if (handlerForPush != null) {
-            handlerForPush.onAbortPush(newChangeHandler, newController);
-            inProgressPushHandlers.remove(toAbort.getInstanceId());
+    static void abortOrComplete(@NonNull Controller toAbort, @Nullable Controller newController, @NonNull ControllerChangeHandler newChangeHandler) {
+        ChangeHandlerData changeHandlerData = inProgressChangeHandlers.get(toAbort.getInstanceId());
+        if (changeHandlerData != null) {
+            if (changeHandlerData.isPush) {
+                changeHandlerData.changeHandler.onAbortPush(newChangeHandler, newController);
+            } else {
+                changeHandlerData.changeHandler.completeImmediately();
+            }
+
+            inProgressChangeHandlers.remove(toAbort.getInstanceId());
         }
     }
 
-    public static void executeChange(@Nullable final Controller to, @Nullable final Controller from, boolean isPush, @NonNull ViewGroup container, @NonNull ControllerChangeHandler inHandler) {
-        executeChange(to, from, isPush, container, inHandler, new ArrayList<ControllerChangeListener>());
+    static void executeChange(@NonNull final ChangeTransaction transaction) {
+        executeChange(transaction.to, transaction.from, transaction.isPush, transaction.container, transaction.changeHandler, transaction.listeners);
     }
 
-    public static void executeChange(@Nullable final Controller to, @Nullable final Controller from, final boolean isPush, @Nullable final ViewGroup container, @Nullable final ControllerChangeHandler inHandler, @NonNull final List<ControllerChangeListener> listeners) {
-        if (isPush && to != null && to.isDestroyed()) {
-            throw new IllegalStateException("Trying to push a controller that has already been destroyed. (" + to.getClass().getSimpleName() + ")");
-        }
-
+    private static void executeChange(@Nullable final Controller to, @Nullable final Controller from, final boolean isPush, @Nullable final ViewGroup container, @Nullable final ControllerChangeHandler inHandler, @NonNull final List<ControllerChangeListener> listeners) {
         if (container != null) {
             final ControllerChangeHandler handler;
             if (inHandler == null) {
@@ -165,14 +166,16 @@ public abstract class ControllerChangeHandler {
             }
             handler.hasBeenUsed = true;
 
-            if (isPush && to != null) {
-                inProgressPushHandlers.put(to.getInstanceId(), handler);
-
-                if (from != null) {
-                    completePushImmediately(from.getInstanceId());
+            if (from != null) {
+                if (isPush) {
+                    completeHandlerImmediately(from.getInstanceId());
+                } else {
+                    abortOrComplete(from, to, handler);
                 }
-            } else if (!isPush && from != null) {
-                abortPush(from, to, handler);
+            }
+
+            if (to != null) {
+                inProgressChangeHandlers.put(to.getInstanceId(), new ChangeHandlerData(handler, isPush));
             }
 
             for (ControllerChangeListener listener : listeners) {
@@ -206,7 +209,7 @@ public abstract class ControllerChangeHandler {
                     }
 
                     if (to != null) {
-                        inProgressPushHandlers.remove(to.getInstanceId());
+                        inProgressChangeHandlers.remove(to.getInstanceId());
                         to.changeEnded(handler, toChangeType);
                     }
 
@@ -220,11 +223,17 @@ public abstract class ControllerChangeHandler {
                             ((ViewGroup)fromParent).removeView(fromView);
                         }
                     }
+
+                    if (handler.removesFromViewOnPush() && from != null) {
+                        from.setNeedsAttach(false);
+                    }
                 }
             });
         }
     }
 
+    protected void onEnd(){ }
+
     public boolean removesFromViewOnPush() {
         return true;
     }
@@ -233,6 +242,24 @@ public abstract class ControllerChangeHandler {
         forceRemoveViewOnPush = force;
     }
 
+    static class ChangeTransaction {
+        @Nullable final Controller to;
+        @Nullable final Controller from;
+        final boolean isPush;
+        @Nullable final ViewGroup container;
+        @Nullable final ControllerChangeHandler changeHandler;
+        @NonNull final List<ControllerChangeListener> listeners;
+
+        public ChangeTransaction(@Nullable Controller to, @Nullable Controller from, boolean isPush, @Nullable ViewGroup container, @Nullable ControllerChangeHandler changeHandler, @NonNull List<ControllerChangeListener> listeners) {
+            this.to = to;
+            this.from = from;
+            this.isPush = isPush;
+            this.container = container;
+            this.changeHandler = changeHandler;
+            this.listeners = listeners;
+        }
+    }
+
     /**
      * A listener interface useful for allowing external classes to be notified of change events.
      */
@@ -240,8 +267,8 @@ public abstract class ControllerChangeHandler {
         /**
          * Called when a {@link ControllerChangeHandler} has started changing {@link Controller}s
          *
-         * @param to        The new Controller
-         * @param from      The old Controller
+         * @param to        The new Controller or {@code null} if no Controller is being transitioned to
+         * @param from      The old Controller or {@code null} if there was no Controller before this transition
          * @param isPush    True if this is a push operation, or false if it's a pop.
          * @param container The containing ViewGroup
          * @param handler   The change handler being used.
@@ -251,9 +278,9 @@ public abstract class ControllerChangeHandler {
         /**
          * Called when a {@link ControllerChangeHandler} has completed changing {@link Controller}s
          *
-         * @param to        The new Controller
-         * @param from      The old Controller
-         * @param isPush    True if this was a push operation, or false if it's a pop.
+         * @param to        The new Controller or {@code null} if no Controller is being transitioned to
+         * @param from      The old Controller or {@code null} if there was no Controller before this transition
+         * @param isPush    True if this was a push operation, or false if it's a pop
          * @param container The containing ViewGroup
          * @param handler   The change handler that was used.
          */
@@ -271,4 +298,14 @@ public abstract class ControllerChangeHandler {
         void onChangeCompleted();
     }
 
+    private static class ChangeHandlerData {
+        public final ControllerChangeHandler changeHandler;
+        public final boolean isPush;
+
+        public ChangeHandlerData(ControllerChangeHandler changeHandler, boolean isPush) {
+            this.changeHandler = changeHandler;
+            this.isPush = isPush;
+        }
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/ControllerHostedRouter.java

@@ -2,16 +2,20 @@ package com.bluelinelabs.conductor;
 
 import android.app.Activity;
 import android.content.Intent;
+import android.content.IntentSender;
+import android.content.IntentSender.SendIntentException;
 import android.os.Bundle;
-import android.support.annotation.IdRes;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.IdRes;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
+import com.bluelinelabs.conductor.internal.TransactionIndexer;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 class ControllerHostedRouter extends Router {
 
@@ -22,6 +26,7 @@ class ControllerHostedRouter extends Router {
 
     @IdRes private int hostId;
     private String tag;
+    private boolean isDetachFrozen;
 
     ControllerHostedRouter() { }
 
@@ -40,6 +45,12 @@ class ControllerHostedRouter extends Router {
 
             hostController = controller;
             this.container = container;
+
+            for (RouterTransaction transaction : backstack) {
+                transaction.controller.setParentController(controller);
+            }
+
+            watchContainerAttach();
         }
     }
 
@@ -51,12 +62,12 @@ class ControllerHostedRouter extends Router {
         final List<Controller> controllersToDestroy = new ArrayList<>(destroyingControllers);
         for (Controller controller : controllersToDestroy) {
             if (controller.getView() != null) {
-                controller.detach(controller.getView(), true);
+                controller.detach(controller.getView(), true, false);
             }
         }
         for (RouterTransaction transaction : backstack) {
             if (transaction.controller.getView() != null) {
-                transaction.controller.detach(transaction.controller.getView(), true);
+                transaction.controller.detach(transaction.controller.getView(), true, false);
             }
         }
 
@@ -66,6 +77,7 @@ class ControllerHostedRouter extends Router {
     }
 
     final void setDetachFrozen(boolean frozen) {
+        isDetachFrozen = frozen;
         for (RouterTransaction transaction : backstack) {
             transaction.controller.setDetachFrozen(frozen);
         }
@@ -77,6 +89,24 @@ class ControllerHostedRouter extends Router {
         super.destroy(popViews);
     }
 
+    @Override
+    protected void pushToBackstack(@NonNull RouterTransaction entry) {
+        if (isDetachFrozen) {
+            entry.controller.setDetachFrozen(true);
+        }
+        super.pushToBackstack(entry);
+    }
+
+    @Override
+    public void setBackstack(@NonNull List<RouterTransaction> newBackstack, @Nullable ControllerChangeHandler changeHandler) {
+        if (isDetachFrozen) {
+            for (RouterTransaction transaction : newBackstack) {
+                transaction.controller.setDetachFrozen(true);
+            }
+        }
+        super.setBackstack(newBackstack, changeHandler);
+    }
+
     @Override @Nullable
     public Activity getActivity() {
         return hostController != null ? hostController.getActivity() : null;
@@ -124,6 +154,13 @@ class ControllerHostedRouter extends Router {
         }
     }
 
+    @Override
+    void startIntentSenderForResult(@NonNull String instanceId, @NonNull IntentSender intent, int requestCode, @Nullable Intent fillInIntent, int flagsMask, int flagsValues, int extraFlags, @Nullable Bundle options) throws SendIntentException {
+        if (hostController != null && hostController.getRouter() != null) {
+            hostController.getRouter().startIntentSenderForResult(instanceId, intent, requestCode, fillInIntent, flagsMask, flagsValues, extraFlags, options);
+        }
+    }
+
     @Override
     void registerForActivityResult(@NonNull String instanceId, int requestCode) {
         if (hostController != null && hostController.getRouter() != null) {
@@ -168,8 +205,8 @@ class ControllerHostedRouter extends Router {
 
     @Override
     void setControllerRouter(@NonNull Controller controller) {
-        super.setControllerRouter(controller);
         controller.setParentController(hostController);
+        super.setControllerRouter(controller);
     }
 
     int getHostId() {
@@ -197,4 +234,22 @@ class ControllerHostedRouter extends Router {
             return this;
         }
     }
+
+    @Override @NonNull
+    TransactionIndexer getTransactionIndexer() {
+        Router rootRouter = getRootRouter();
+        if (rootRouter == this) {
+            String debugInfo;
+            if (hostController != null) {
+                debugInfo = String.format(Locale.ENGLISH, "%s (attached? %b, destroyed? %b, parent: %s)",
+                        hostController.getClass().getSimpleName(), hostController.isAttached(), hostController.isBeingDestroyed, hostController.getParentController());
+            } else {
+                debugInfo = "null host controller";
+            }
+            throw new IllegalStateException("Unable to retrieve TransactionIndexer from " + debugInfo);
+        } else {
+            return getRootRouter().getTransactionIndexer();
+        }
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/RestoreViewOnCreateController.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -32,7 +32,7 @@ abstract public class RestoreViewOnCreateController extends Controller {
 
     @Override @NonNull
     protected final View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
-        return onCreateView(inflater, container, viewState);
+        return onCreateView(inflater, container, viewState == null ? null : viewState.getBundle(KEY_VIEW_STATE_BUNDLE));
     }
 
     /**
@@ -45,7 +45,7 @@ abstract public class RestoreViewOnCreateController extends Controller {
      *                       This Controller's view should NOT be added in this method. It is simply passed in
      *                       so that valid LayoutParams can be used during inflation.
      * @param savedViewState A bundle for the view's state, which would have been created in {@link #onSaveViewState(View, Bundle)},
-     *                       or null if no saved state exists.
+     *                       or {@code null} if no saved state exists.
      */
     @NonNull
     protected abstract View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container, @Nullable Bundle savedViewState);

conductor/src/main/java/com/bluelinelabs/conductor/Router.java

@@ -2,10 +2,8 @@ package com.bluelinelabs.conductor;
 
 import android.app.Activity;
 import android.content.Intent;
+import android.content.IntentSender;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.support.annotation.UiThread;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
@@ -13,15 +11,22 @@ import android.view.View;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.Controller.LifecycleListener;
+import com.bluelinelabs.conductor.ControllerChangeHandler.ChangeTransaction;
 import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
 import com.bluelinelabs.conductor.changehandler.SimpleSwapChangeHandler;
 import com.bluelinelabs.conductor.internal.NoOpControllerChangeHandler;
+import com.bluelinelabs.conductor.internal.ThreadUtils;
+import com.bluelinelabs.conductor.internal.TransactionIndexer;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+
 /**
  * A Router implements navigation and backstack handling for {@link Controller}s. Router objects are attached
  * to Activity/containing ViewGroup pairs. Routers do not directly render or push Views to the container ViewGroup,
@@ -32,17 +37,20 @@ public abstract class Router {
     private static final String KEY_BACKSTACK = "Router.backstack";
     private static final String KEY_POPS_LAST_VIEW = "Router.popsLastView";
 
-    protected final Backstack backstack = new Backstack();
-    private OnControllerPushedListener onControllerPushedListener;
+    final Backstack backstack = new Backstack();
     private final List<ControllerChangeListener> changeListeners = new ArrayList<>();
+    private final List<ChangeTransaction> pendingControllerChanges = new ArrayList<>();
     final List<Controller> destroyingControllers = new ArrayList<>();
 
     private boolean popsLastView = false;
+    boolean containerFullyAttached = false;
+    boolean isActivityStopped = false;
 
     ViewGroup container;
 
     /**
-     * Returns this Router's host Activity
+     * Returns this Router's host Activity or {@code null} if it has either not yet been attached to
+     * an Activity or if the Activity has been destroyed.
      */
     @Nullable
     public abstract Activity getActivity();
@@ -52,8 +60,8 @@ public abstract class Router {
      * of the controller that called startActivityForResult is not known.
      *
      * @param requestCode The Activity's onActivityResult requestCode
-     * @param resultCode The Activity's onActivityResult resultCode
-     * @param data The Activity's onActivityResult data
+     * @param resultCode  The Activity's onActivityResult resultCode
+     * @param data        The Activity's onActivityResult data
      */
     public abstract void onActivityResult(int requestCode, int resultCode, @Nullable Intent data);
 
@@ -61,9 +69,9 @@ public abstract class Router {
      * This should be called by the host Activity when its onRequestPermissionsResult method is called. The call will be forwarded
      * to the {@link Controller} with the instanceId passed in.
      *
-     * @param instanceId The instanceId of the Controller to which this result should be forwarded
-     * @param requestCode The Activity's onRequestPermissionsResult requestCode
-     * @param permissions The Activity's onRequestPermissionsResult permissions
+     * @param instanceId   The instanceId of the Controller to which this result should be forwarded
+     * @param requestCode  The Activity's onRequestPermissionsResult requestCode
+     * @param permissions  The Activity's onRequestPermissionsResult permissions
      * @param grantResults The Activity's onRequestPermissionsResult grantResults
      */
     public void onRequestPermissionsResult(@NonNull String instanceId, int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
@@ -81,6 +89,8 @@ public abstract class Router {
      */
     @UiThread
     public boolean handleBack() {
+        ThreadUtils.ensureMainThread();
+
         if (!backstack.isEmpty()) {
             //noinspection ConstantConditions
             if (backstack.peek().controller.handleBack()) {
@@ -98,8 +108,11 @@ public abstract class Router {
      *
      * @return Whether or not this Router still has controllers remaining on it after popping.
      */
+    @SuppressWarnings("WeakerAccess")
     @UiThread
     public boolean popCurrentController() {
+        ThreadUtils.ensureMainThread();
+
         RouterTransaction transaction = backstack.peek();
         if (transaction == null) {
             throw new IllegalStateException("Trying to pop the current controller when there are none on the backstack.");
@@ -115,26 +128,44 @@ public abstract class Router {
      */
     @UiThread
     public boolean popController(@NonNull Controller controller) {
-        RouterTransaction topController = backstack.peek();
-        boolean poppingTopController = topController != null && topController.controller == controller;
+        ThreadUtils.ensureMainThread();
+
+        RouterTransaction topTransaction = backstack.peek();
+        boolean poppingTopController = topTransaction != null && topTransaction.controller == controller;
 
         if (poppingTopController) {
             trackDestroyingController(backstack.pop());
+            performControllerChange(backstack.peek(), topTransaction, false);
         } else {
-            for (RouterTransaction transaction : backstack) {
+            RouterTransaction removedTransaction = null;
+            RouterTransaction nextTransaction = null;
+            Iterator<RouterTransaction> iterator = backstack.iterator();
+            ControllerChangeHandler topPushHandler = topTransaction != null ? topTransaction.pushChangeHandler() : null;
+            final boolean needsNextTransactionAttach = topPushHandler != null ? !topPushHandler.removesFromViewOnPush() : false;
+
+            while (iterator.hasNext()) {
+                RouterTransaction transaction = iterator.next();
                 if (transaction.controller == controller) {
-                    backstack.remove(transaction);
+                    if (controller.isAttached()) {
+                        trackDestroyingController(transaction);
+                    }
+                    iterator.remove();
+                    removedTransaction = transaction;
+                } else if (removedTransaction != null) {
+                    if (needsNextTransactionAttach && !transaction.controller.isAttached()) {
+                        nextTransaction = transaction;
+                    }
                     break;
                 }
             }
-        }
 
-        if (poppingTopController) {
-            performControllerChange(backstack.peek(), topController, false);
+            if (removedTransaction != null) {
+                performControllerChange(nextTransaction, removedTransaction, false);
+            }
         }
 
         if (popsLastView) {
-            return topController != null;
+            return topTransaction != null;
         } else {
             return !backstack.isEmpty();
         }
@@ -148,6 +179,8 @@ public abstract class Router {
      */
     @UiThread
     public void pushController(@NonNull RouterTransaction transaction) {
+        ThreadUtils.ensureMainThread();
+
         RouterTransaction from = backstack.peek();
         pushToBackstack(transaction);
         performControllerChange(transaction, from, true);
@@ -159,8 +192,11 @@ public abstract class Router {
      * @param transaction The transaction detailing what should be pushed, including the {@link Controller},
      *                    and its push and pop {@link ControllerChangeHandler}, and its tag.
      */
+    @SuppressWarnings("WeakerAccess")
     @UiThread
     public void replaceTopController(@NonNull RouterTransaction transaction) {
+        ThreadUtils.ensureMainThread();
+
         RouterTransaction topTransaction = backstack.peek();
         if (!backstack.isEmpty()) {
             trackDestroyingController(backstack.pop());
@@ -168,11 +204,12 @@ public abstract class Router {
 
         final ControllerChangeHandler handler = transaction.pushChangeHandler();
         if (topTransaction != null) {
+            //noinspection ConstantConditions
             final boolean oldHandlerRemovedViews = topTransaction.pushChangeHandler() == null || topTransaction.pushChangeHandler().removesFromViewOnPush();
             final boolean newHandlerRemovesViews = handler == null || handler.removesFromViewOnPush();
             if (!oldHandlerRemovedViews && newHandlerRemovesViews) {
                 for (RouterTransaction visibleTransaction : getVisibleTransactions(backstack.iterator())) {
-                    performControllerChange(null, visibleTransaction.controller, true, handler);
+                    performControllerChange(null, visibleTransaction, true, handler);
                 }
             }
         }
@@ -187,12 +224,24 @@ public abstract class Router {
 
     void destroy(boolean popViews) {
         popsLastView = true;
-        List<RouterTransaction> poppedControllers = backstack.popAll();
+        final List<RouterTransaction> poppedControllers = backstack.popAll();
+        trackDestroyingControllers(poppedControllers);
 
         if (popViews && poppedControllers.size() > 0) {
-            trackDestroyingControllers(poppedControllers);
+            RouterTransaction topTransaction = poppedControllers.get(0);
+            topTransaction.controller().addLifecycleListener(new LifecycleListener() {
+                @Override
+                public void onChangeEnd(@NonNull Controller controller, @NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
+                    if (changeType == ControllerChangeType.POP_EXIT) {
+                        for (int i = poppedControllers.size() - 1; i > 0; i--) {
+                            RouterTransaction transaction = poppedControllers.get(i);
+                            performControllerChange(null, transaction, true, new SimpleSwapChangeHandler());
+                        }
+                    }
+                }
+            });
 
-            performControllerChange(null, poppedControllers.get(0).controller, false, poppedControllers.get(0).popChangeHandler());
+            performControllerChange(null, topTransaction, false, topTransaction.popChangeHandler());
         }
     }
 
@@ -218,6 +267,8 @@ public abstract class Router {
      */
     @UiThread
     public boolean popToRoot() {
+        ThreadUtils.ensureMainThread();
+
         return popToRoot(null);
     }
 
@@ -227,8 +278,11 @@ public abstract class Router {
      * @param changeHandler The {@link ControllerChangeHandler} to handle this transaction
      * @return Whether or not any {@link Controller}s were popped in order to get to the root transaction
      */
+    @SuppressWarnings("WeakerAccess")
     @UiThread
     public boolean popToRoot(@Nullable ControllerChangeHandler changeHandler) {
+        ThreadUtils.ensureMainThread();
+
         if (backstack.size() > 1) {
             //noinspection ConstantConditions
             popToTransaction(backstack.root(), changeHandler);
@@ -246,18 +300,23 @@ public abstract class Router {
      */
     @UiThread
     public boolean popToTag(@NonNull String tag) {
+        ThreadUtils.ensureMainThread();
+
         return popToTag(tag, null);
     }
 
     /**
      * Pops all {@link Controller}s until the {@link Controller} with the passed tag is at the top
      *
-     * @param tag The tag being popped to
+     * @param tag           The tag being popped to
      * @param changeHandler The {@link ControllerChangeHandler} to handle this transaction
      * @return Whether or not the {@link Controller} with the passed tag is now at the top
      */
+    @SuppressWarnings("WeakerAccess")
     @UiThread
     public boolean popToTag(@NonNull String tag, @Nullable ControllerChangeHandler changeHandler) {
+        ThreadUtils.ensureMainThread();
+
         for (RouterTransaction transaction : backstack) {
             if (tag.equals(transaction.tag())) {
                 popToTransaction(transaction, changeHandler);
@@ -275,16 +334,17 @@ public abstract class Router {
      */
     @UiThread
     public void setRoot(@NonNull RouterTransaction transaction) {
-        List<RouterTransaction> transactions = new ArrayList<>();
-        transactions.add(transaction);
+        ThreadUtils.ensureMainThread();
+
+        List<RouterTransaction> transactions = Collections.singletonList(transaction);
         setBackstack(transactions, transaction.pushChangeHandler());
     }
 
     /**
-     * Returns the hosted Controller with the given instance id, if available.
+     * Returns the hosted Controller with the given instance id or {@code null} if no such
+     * Controller exists in this Router.
      *
      * @param instanceId The instance ID being searched for
-     * @return The matching Controller, if one exists
      */
     @Nullable
     public Controller getControllerWithInstanceId(@NonNull String instanceId) {
@@ -298,10 +358,10 @@ public abstract class Router {
     }
 
     /**
-     * Returns the hosted Controller that was pushed with the given tag, if available.
+     * Returns the hosted Controller that was pushed with the given tag or {@code null} if no
+     * such Controller exists in this Router.
      *
      * @param tag The tag being searched for
-     * @return The matching Controller, if one exists
      */
     @Nullable
     public Controller getControllerWithTag(@NonNull String tag) {
@@ -316,6 +376,7 @@ public abstract class Router {
     /**
      * Returns the number of {@link Controller}s currently in the backstack
      */
+    @SuppressWarnings("WeakerAccess")
     public int getBackstackSize() {
         return backstack.size();
     }
@@ -325,7 +386,7 @@ public abstract class Router {
      */
     @NonNull
     public List<RouterTransaction> getBackstack() {
-        List<RouterTransaction> list = new ArrayList<>();
+        List<RouterTransaction> list = new ArrayList<>(backstack.size());
         Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             list.add(backstackIterator.next());
@@ -337,52 +398,113 @@ public abstract class Router {
      * Sets the backstack, transitioning from the current top controller to the top of the new stack (if different)
      * using the passed {@link ControllerChangeHandler}
      *
-     * @param newBackstack The new backstack
+     * @param newBackstack  The new backstack
      * @param changeHandler An optional change handler to be used to handle the root view of transition
      */
+    @SuppressWarnings("WeakerAccess")
     @UiThread
     public void setBackstack(@NonNull List<RouterTransaction> newBackstack, @Nullable ControllerChangeHandler changeHandler) {
+        ThreadUtils.ensureMainThread();
+
+        List<RouterTransaction> oldTransactions = getBackstack();
         List<RouterTransaction> oldVisibleTransactions = getVisibleTransactions(backstack.iterator());
 
         removeAllExceptVisibleAndUnowned();
+        ensureOrderedTransactionIndices(newBackstack);
+        ensureNoDuplicateControllers(newBackstack);
 
         backstack.setBackstack(newBackstack);
-        for (RouterTransaction transaction : backstack) {
+
+        List<RouterTransaction> transactionsToBeRemoved = new ArrayList<>();
+        for (RouterTransaction oldTransaction : oldTransactions) {
+            boolean contains = false;
+            for (RouterTransaction newTransaction : newBackstack) {
+                if (oldTransaction.controller == newTransaction.controller) {
+                    contains = true;
+                    break;
+                }
+            }
+
+            if (!contains) {
+                // Inform the controller that it will be destroyed soon
+                oldTransaction.controller.isBeingDestroyed = true;
+                transactionsToBeRemoved.add(oldTransaction);
+            }
+        }
+
+        // Ensure all new controllers have a valid router set
+        Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
+        while (backstackIterator.hasNext()) {
+            RouterTransaction transaction = backstackIterator.next();
             transaction.onAttachedToRouter();
+            setControllerRouter(transaction.controller);
         }
 
         if (newBackstack.size() > 0) {
             List<RouterTransaction> reverseNewBackstack = new ArrayList<>(newBackstack);
             Collections.reverse(reverseNewBackstack);
             List<RouterTransaction> newVisibleTransactions = getVisibleTransactions(reverseNewBackstack.iterator());
+            boolean newRootRequiresPush = !(newVisibleTransactions.size() > 0 && oldTransactions.contains(newVisibleTransactions.get(0)));
 
             boolean visibleTransactionsChanged = !backstacksAreEqual(newVisibleTransactions, oldVisibleTransactions);
             if (visibleTransactionsChanged) {
-                Controller rootController = oldVisibleTransactions.size() > 0 ? oldVisibleTransactions.get(0).controller : null;
-                performControllerChange(newVisibleTransactions.get(0).controller, rootController, true, changeHandler);
+                RouterTransaction oldRootTransaction = oldVisibleTransactions.size() > 0 ? oldVisibleTransactions.get(0) : null;
+                RouterTransaction newRootTransaction = newVisibleTransactions.get(0);
 
-                for (int i = oldVisibleTransactions.size() - 1; i > 0; i--) {
-                    RouterTransaction transaction = oldVisibleTransactions.get(i);
-                    ControllerChangeHandler localHandler = changeHandler != null ? changeHandler.copy() : new SimpleSwapChangeHandler();
-                    localHandler.setForceRemoveViewOnPush(true);
-                    performControllerChange(null, transaction.controller, true, localHandler);
+                // Replace the old root with the new one
+                if (oldRootTransaction == null || oldRootTransaction.controller != newRootTransaction.controller) {
+                    // Ensure the existing root controller is fully pushed to the view hierarchy
+                    if (oldRootTransaction != null) {
+                        ControllerChangeHandler.completeHandlerImmediately(oldRootTransaction.controller.getInstanceId());
+                    }
+                    performControllerChange(newRootTransaction, oldRootTransaction, newRootRequiresPush, changeHandler);
                 }
 
+                // Remove all visible controllers that were previously on the backstack
+                for (int i = oldVisibleTransactions.size() - 1; i > 0; i--) {
+                    RouterTransaction transaction = oldVisibleTransactions.get(i);
+                    if (!newVisibleTransactions.contains(transaction)) {
+                        ControllerChangeHandler localHandler = changeHandler != null ? changeHandler.copy() : new SimpleSwapChangeHandler();
+                        localHandler.setForceRemoveViewOnPush(true);
+                        ControllerChangeHandler.completeHandlerImmediately(transaction.controller.getInstanceId());
+                        performControllerChange(null, transaction, newRootRequiresPush, localHandler);
+                    }
+                }
+
+                // Add any new controllers to the backstack
                 for (int i = 1; i < newVisibleTransactions.size(); i++) {
                     RouterTransaction transaction = newVisibleTransactions.get(i);
-                    performControllerChange(transaction.controller, newVisibleTransactions.get(i - 1).controller, true, transaction.pushChangeHandler());
+                    if (!oldVisibleTransactions.contains(transaction)) {
+                        performControllerChange(transaction, newVisibleTransactions.get(i - 1), true, transaction.pushChangeHandler());
+                    }
                 }
             }
 
-            // Ensure all new controllers have a valid router set
-            for (RouterTransaction transaction : newBackstack) {
-                transaction.controller.setRouter(this);
+        } else {
+            // Remove all visible controllers that were previously on the backstack
+            for (int i = oldVisibleTransactions.size() - 1; i >= 0; i--) {
+                RouterTransaction transaction = oldVisibleTransactions.get(i);
+                ControllerChangeHandler localHandler = changeHandler != null ? changeHandler.copy() : new SimpleSwapChangeHandler();
+                ControllerChangeHandler.completeHandlerImmediately(transaction.controller.getInstanceId());
+                performControllerChange(null, transaction, false, localHandler);
             }
         }
 
-        if (onControllerPushedListener != null) {
-            for (RouterTransaction transaction : newBackstack) {
-                onControllerPushedListener.onControllerPushed(transaction.controller);
+        // Destroy all old controllers that are no longer on the backstack. We don't do this when we initially
+        // set the backstack to prevent the possibility that they'll be destroyed before the controller
+        // change handler runs.
+        for (RouterTransaction removedTransaction : transactionsToBeRemoved) {
+
+            // Still need to ensure the controller isn't queued up to be removed later on.
+            boolean willBeRemoved = false;
+            for (ChangeTransaction pendingTransaction : pendingControllerChanges) {
+                if (pendingTransaction.from == removedTransaction.controller) {
+                    willBeRemoved = true;
+                }
+            }
+
+            if (!willBeRemoved) {
+                removedTransaction.controller.destroy();
             }
         }
     }
@@ -399,6 +521,7 @@ public abstract class Router {
      *
      * @param changeListener The listener
      */
+    @SuppressWarnings("WeakerAccess")
     public void addChangeListener(@NonNull ControllerChangeListener changeListener) {
         if (!changeListeners.contains(changeListener)) {
             changeListeners.add(changeListener);
@@ -410,6 +533,7 @@ public abstract class Router {
      *
      * @param changeListener The listener to be removed
      */
+    @SuppressWarnings("WeakerAccess")
     public void removeChangeListener(@NonNull ControllerChangeListener changeListener) {
         changeListeners.remove(changeListener);
     }
@@ -419,12 +543,16 @@ public abstract class Router {
      */
     @UiThread
     public void rebindIfNeeded() {
+        ThreadUtils.ensureMainThread();
+
         Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             RouterTransaction transaction = backstackIterator.next();
 
             if (transaction.controller.getNeedsAttach()) {
-                performControllerChange(transaction.controller, null, true, new SimpleSwapChangeHandler(false));
+                performControllerChange(transaction, null, true, new SimpleSwapChangeHandler(false));
+            } else {
+                setControllerRouter(transaction.controller);
             }
         }
     }
@@ -437,6 +565,8 @@ public abstract class Router {
     }
 
     public final void onActivityStarted(@NonNull Activity activity) {
+        isActivityStopped = false;
+
         for (RouterTransaction transaction : backstack) {
             transaction.controller.activityStarted(activity);
 
@@ -474,6 +604,8 @@ public abstract class Router {
                 childRouter.onActivityStopped(activity);
             }
         }
+
+        isActivityStopped = true;
     }
 
     public void onActivityDestroyed(@NonNull Activity activity) {
@@ -481,7 +613,7 @@ public abstract class Router {
         changeListeners.clear();
 
         for (RouterTransaction transaction : backstack) {
-            transaction.controller.activityDestroyed(activity.isChangingConfigurations());
+            transaction.controller.activityDestroyed(activity);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
                 childRouter.onActivityDestroyed(activity);
@@ -490,7 +622,7 @@ public abstract class Router {
 
         for (int index = destroyingControllers.size() - 1; index >= 0; index--) {
             Controller controller = destroyingControllers.get(index);
-            controller.activityDestroyed(activity.isChangingConfigurations());
+            controller.activityDestroyed(activity);
 
             for (Router childRouter : controller.getChildRouters()) {
                 childRouter.onActivityDestroyed(activity);
@@ -502,16 +634,14 @@ public abstract class Router {
 
     public void prepareForHostDetach() {
         for (RouterTransaction transaction : backstack) {
-            if (ControllerChangeHandler.completePushImmediately(transaction.controller.getInstanceId())) {
-                transaction.controller.setNeedsAttach();
+            if (ControllerChangeHandler.completeHandlerImmediately(transaction.controller.getInstanceId())) {
+                transaction.controller.setNeedsAttach(true);
             }
             transaction.controller.prepareForHostDetach();
         }
     }
 
     public void saveInstanceState(@NonNull Bundle outState) {
-        prepareForHostDetach();
-
         Bundle backstackState = new Bundle();
         backstack.saveInstanceState(backstackState);
 
@@ -521,6 +651,7 @@ public abstract class Router {
 
     public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
         Bundle backstackBundle = savedInstanceState.getParcelable(KEY_BACKSTACK);
+        //noinspection ConstantConditions
         backstack.restoreInstanceState(backstackBundle);
         popsLastView = savedInstanceState.getBoolean(KEY_POPS_LAST_VIEW);
 
@@ -566,32 +697,54 @@ public abstract class Router {
     }
 
     private void popToTransaction(@NonNull RouterTransaction transaction, @Nullable ControllerChangeHandler changeHandler) {
-        RouterTransaction topTransaction = backstack.peek();
-        List<RouterTransaction> poppedTransactions = backstack.popTo(transaction);
-        trackDestroyingControllers(poppedTransactions);
+        if (backstack.size() > 0) {
+            RouterTransaction topTransaction = backstack.peek();
+
+            List<RouterTransaction> updatedBackstack = new ArrayList<>();
+            Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
+            while (backstackIterator.hasNext()) {
+                RouterTransaction existingTransaction = backstackIterator.next();
+                updatedBackstack.add(existingTransaction);
+                if (existingTransaction == transaction) {
+                    break;
+                }
+            }
 
-        if (poppedTransactions.size() > 0) {
             if (changeHandler == null) {
+                //noinspection ConstantConditions
                 changeHandler = topTransaction.popChangeHandler();
             }
 
-            performControllerChange(backstack.peek().controller, topTransaction.controller, false, changeHandler);
+            setBackstack(updatedBackstack, changeHandler);
         }
     }
 
-    final void setOnControllerPushedListener(OnControllerPushedListener listener) {
-        onControllerPushedListener = listener;
+    void watchContainerAttach() {
+        container.post(new Runnable() {
+            @Override
+            public void run() {
+                containerFullyAttached = true;
+            }
+        });
     }
 
     void prepareForContainerRemoval() {
+        containerFullyAttached = false;
+
         if (container != null) {
             container.setOnHierarchyChangeListener(null);
         }
     }
 
+    void onContextAvailable() {
+        for (RouterTransaction transaction : backstack) {
+            transaction.controller.onContextAvailable();
+        }
+    }
+
     @NonNull
     final List<Controller> getControllers() {
-        List<Controller> controllers = new ArrayList<>();
+        List<Controller> controllers = new ArrayList<>(backstack.size());
 
         Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
@@ -626,30 +779,72 @@ public abstract class Router {
             changeHandler = null;
         }
 
+        performControllerChange(to, from, isPush, changeHandler);
+    }
+
+    void performControllerChange(@Nullable RouterTransaction to, @Nullable RouterTransaction from, boolean isPush, @Nullable ControllerChangeHandler changeHandler) {
         Controller toController = to != null ? to.controller : null;
         Controller fromController = from != null ? from.controller : null;
+        boolean forceDetachDestroy = false;
+
+        if (to != null) {
+            to.ensureValidIndex(getTransactionIndexer());
+            setControllerRouter(toController);
+        } else if (backstack.size() == 0 && !popsLastView) {
+            // We're emptying out the backstack. Views get weird if you transition them out, so just no-op it. The host
+            // Activity or controller should be handling this by finishing or at least hiding this view.
+            changeHandler = new NoOpControllerChangeHandler();
+            forceDetachDestroy = true;
+        }
 
         performControllerChange(toController, fromController, isPush, changeHandler);
+
+        if (forceDetachDestroy && fromController != null && fromController.getView() != null) {
+            fromController.detach(fromController.getView(), true, false);
+        }
     }
 
-    private void performControllerChange(@Nullable final Controller to, @Nullable final Controller from, boolean isPush, @Nullable ControllerChangeHandler changeHandler) {
-        if (to != null) {
-            setControllerRouter(to);
-        } else if (backstack.size() == 0 && !popsLastView) {
-            // We're emptying out the backstack. Views get weird if you transition them out, so just no-op it. The hosting
-            // Activity should be handling this by finishing or at least hiding this view.
-            changeHandler = new NoOpControllerChangeHandler();
+    private void performControllerChange(@Nullable final Controller to, @Nullable final Controller from, final boolean isPush, @Nullable final ControllerChangeHandler changeHandler) {
+        if (isPush && to != null && to.isDestroyed()) {
+            throw new IllegalStateException("Trying to push a controller that has already been destroyed. (" + to.getClass().getSimpleName() + ")");
         }
 
-        ControllerChangeHandler.executeChange(to, from, isPush, container, changeHandler, changeListeners);
+        final ChangeTransaction transaction = new ChangeTransaction(to, from, isPush, container, changeHandler, new ArrayList<>(changeListeners));
+
+        if (pendingControllerChanges.size() > 0) {
+            // If we already have changes queued up (awaiting full container attach), queue this one up as well so they don't happen
+            // out of order.
+            pendingControllerChanges.add(transaction);
+        } else if (from != null && (changeHandler == null || changeHandler.removesFromViewOnPush()) && !containerFullyAttached) {
+            // If the change handler will remove the from view, we have to make sure the container is fully attached first so we avoid NPEs
+            // within ViewGroup (details on issue #287). Post this to the container to ensure the attach is complete before we try to remove
+            // anything.
+            pendingControllerChanges.add(transaction);
+            container.post(new Runnable() {
+                @Override
+                public void run() {
+                    performPendingControllerChanges();
+                }
+            });
+        } else {
+            ControllerChangeHandler.executeChange(transaction);
+        }
     }
 
-    private void pushToBackstack(@NonNull RouterTransaction entry) {
+    void performPendingControllerChanges() {
+        // We're intentionally using dynamic size checking (list.size()) here so we can account for changes
+        // that occur during this loop (ex: if a controller is popped from within onAttach)
+        for (int i = 0; i < pendingControllerChanges.size(); i++) {
+            ControllerChangeHandler.executeChange(pendingControllerChanges.get(i));
+        }
+        pendingControllerChanges.clear();
+    }
+
+    protected void pushToBackstack(@NonNull RouterTransaction entry) {
+        if (backstack.contains(entry.controller)) {
+            throw new IllegalStateException("Trying to push a controller that already exists on the backstack.");
+        }
         backstack.push(entry);
-
-        if (onControllerPushedListener != null) {
-            onControllerPushedListener.onControllerPushed(entry.controller);
-        }
     }
 
     private void trackDestroyingController(@NonNull RouterTransaction transaction) {
@@ -687,7 +882,7 @@ public abstract class Router {
         }
 
         final int childCount = container.getChildCount();
-        for (int i = 0; i < childCount; i++) {
+        for (int i = childCount - 1; i >= 0; i--) {
             final View child = container.getChildAt(i);
             if (!views.contains(child)) {
                 container.removeView(child);
@@ -695,6 +890,33 @@ public abstract class Router {
         }
     }
 
+    // Swap around transaction indices to ensure they don't get thrown out of order by the
+    // developer rearranging the backstack at runtime.
+    private void ensureOrderedTransactionIndices(List<RouterTransaction> backstack) {
+        List<Integer> indices = new ArrayList<>(backstack.size());
+        for (RouterTransaction transaction : backstack) {
+            transaction.ensureValidIndex(getTransactionIndexer());
+            indices.add(transaction.transactionIndex);
+        }
+
+        Collections.sort(indices);
+
+        for (int i = 0; i < backstack.size(); i++) {
+            backstack.get(i).transactionIndex = indices.get(i);
+        }
+    }
+
+    private void ensureNoDuplicateControllers(List<RouterTransaction> backstack) {
+        for (int i = 0; i < backstack.size(); i++) {
+            Controller controller = backstack.get(i).controller;
+            for (int j = i + 1; j < backstack.size(); j++) {
+                if (backstack.get(j).controller == controller) {
+                    throw new IllegalStateException("Trying to push the same controller to the backstack more than once.");
+                }
+            }
+        }
+    }
+
     private void addRouterViewsToList(@NonNull Router router, @NonNull List<View> list) {
         for (Controller controller : router.getControllers()) {
             if (controller.getView() != null) {
@@ -713,6 +935,7 @@ public abstract class Router {
             RouterTransaction transaction = backstackIterator.next();
             transactions.add(transaction);
 
+            //noinspection ConstantConditions
             if (transaction.pushChangeHandler() == null || transaction.pushChangeHandler().removesFromViewOnPush()) {
                 break;
             }
@@ -738,20 +961,21 @@ public abstract class Router {
 
     void setControllerRouter(@NonNull Controller controller) {
         controller.setRouter(this);
+        controller.onContextAvailable();
     }
 
     abstract void invalidateOptionsMenu();
     abstract void startActivity(@NonNull Intent intent);
     abstract void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode);
     abstract void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode, @Nullable Bundle options);
+    abstract void startIntentSenderForResult(@NonNull String instanceId, @NonNull IntentSender intent, int requestCode, @Nullable Intent fillInIntent, int flagsMask,
+                                             int flagsValues, int extraFlags, @Nullable Bundle options) throws IntentSender.SendIntentException;
     abstract void registerForActivityResult(@NonNull String instanceId, int requestCode);
     abstract void unregisterForActivityResults(@NonNull String instanceId);
     abstract void requestPermissions(@NonNull String instanceId, @NonNull String[] permissions, int requestCode);
     abstract boolean hasHost();
     @NonNull abstract List<Router> getSiblingRouters();
     @NonNull abstract Router getRootRouter();
+    @NonNull abstract TransactionIndexer getTransactionIndexer();
 
-    interface OnControllerPushedListener {
-        void onControllerPushed(Controller controller);
-    }
 }

conductor/src/main/java/com/bluelinelabs/conductor/RouterTransaction.java

@@ -1,18 +1,23 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.bluelinelabs.conductor.internal.TransactionIndexer;
 
 /**
  * Metadata used for adding {@link Controller}s to a {@link Router}.
  */
 public class RouterTransaction {
 
+    private static int INVALID_INDEX = -1;
+
     private static final String KEY_VIEW_CONTROLLER_BUNDLE = "RouterTransaction.controller.bundle";
     private static final String KEY_PUSH_TRANSITION = "RouterTransaction.pushControllerChangeHandler";
     private static final String KEY_POP_TRANSITION = "RouterTransaction.popControllerChangeHandler";
     private static final String KEY_TAG = "RouterTransaction.tag";
+    private static final String KEY_INDEX = "RouterTransaction.transactionIndex";
     private static final String KEY_ATTACHED_TO_ROUTER = "RouterTransaction.attachedToRouter";
 
     @NonNull final Controller controller;
@@ -21,6 +26,7 @@ public class RouterTransaction {
     private ControllerChangeHandler pushControllerChangeHandler;
     private ControllerChangeHandler popControllerChangeHandler;
     private boolean attachedToRouter;
+    int transactionIndex = INVALID_INDEX;
 
     @NonNull
     public static RouterTransaction with(@NonNull Controller controller) {
@@ -36,6 +42,7 @@ public class RouterTransaction {
         pushControllerChangeHandler = ControllerChangeHandler.fromBundle(bundle.getBundle(KEY_PUSH_TRANSITION));
         popControllerChangeHandler = ControllerChangeHandler.fromBundle(bundle.getBundle(KEY_POP_TRANSITION));
         tag = bundle.getString(KEY_TAG);
+        transactionIndex = bundle.getInt(KEY_INDEX);
         attachedToRouter = bundle.getBoolean(KEY_ATTACHED_TO_ROUTER);
     }
 
@@ -101,6 +108,12 @@ public class RouterTransaction {
         }
     }
 
+    void ensureValidIndex(@NonNull TransactionIndexer indexer) {
+        if (transactionIndex == INVALID_INDEX) {
+            transactionIndex = indexer.nextIndex();
+        }
+    }
+
     /**
      * Used to serialize this transaction into a Bundle
      */
@@ -118,9 +131,10 @@ public class RouterTransaction {
         }
 
         bundle.putString(KEY_TAG, tag);
+        bundle.putInt(KEY_INDEX, transactionIndex);
         bundle.putBoolean(KEY_ATTACHED_TO_ROUTER, attachedToRouter);
 
         return bundle;
     }
 
-}
+}

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/AnimatorChangeHandler.java

@@ -4,8 +4,8 @@ import android.animation.Animator;
 import android.animation.Animator.AnimatorListener;
 import android.animation.AnimatorListenerAdapter;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewTreeObserver;
@@ -21,23 +21,28 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
     private static final String KEY_DURATION = "AnimatorChangeHandler.duration";
     private static final String KEY_REMOVES_FROM_ON_PUSH = "AnimatorChangeHandler.removesFromViewOnPush";
 
+    @SuppressWarnings("WeakerAccess")
     public static final long DEFAULT_ANIMATION_DURATION = -1;
 
     private long animationDuration;
-    private boolean removesFromViewOnPush;
-    private boolean canceled;
-    private boolean needsImmediateCompletion;
+    boolean removesFromViewOnPush;
+    boolean canceled;
+    boolean needsImmediateCompletion;
     private boolean completed;
-    private Animator animator;
+    Animator animator;
+    private OnAnimationReadyOrAbortedListener onAnimationReadyOrAbortedListener;
 
+    @SuppressWarnings("WeakerAccess")
     public AnimatorChangeHandler() {
         this(DEFAULT_ANIMATION_DURATION, true);
     }
 
+    @SuppressWarnings("WeakerAccess")
     public AnimatorChangeHandler(boolean removesFromViewOnPush) {
         this(DEFAULT_ANIMATION_DURATION, removesFromViewOnPush);
     }
 
+    @SuppressWarnings("WeakerAccess")
     public AnimatorChangeHandler(long duration) {
         this(duration, true);
     }
@@ -68,6 +73,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         canceled = true;
         if (animator != null) {
             animator.cancel();
+        } else if (onAnimationReadyOrAbortedListener != null) {
+            onAnimationReadyOrAbortedListener.onReadyOrAborted();
         }
     }
 
@@ -78,6 +85,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         needsImmediateCompletion = true;
         if (animator != null) {
             animator.end();
+        } else if (onAnimationReadyOrAbortedListener != null) {
+            onAnimationReadyOrAbortedListener.onReadyOrAborted();
         }
     }
 
@@ -94,8 +103,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
      * Should be overridden to return the Animator to use while replacing Views.
      *
      * @param container The container these Views are hosted in.
-     * @param from The previous View in the container, if any.
-     * @param to The next View that should be put in the container, if any.
+     * @param from The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to The next View that should be put in the container or {@code null} if no Controller is being transitioned to
      * @param isPush True if this is a push transaction, false if it's a pop.
      * @param toAddedToContainer True if the "to" view was added to the container as a part of this ChangeHandler. False if it was already in the hierarchy.
      */
@@ -121,17 +130,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
 
             if (to.getWidth() <= 0 && to.getHeight() <= 0) {
                 readyToAnimate = false;
-                to.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
-                    @Override
-                    public boolean onPreDraw() {
-                        final ViewTreeObserver observer = to.getViewTreeObserver();
-                        if (observer.isAlive()) {
-                            observer.removeOnPreDrawListener(this);
-                        }
-                        performAnimation(container, from, to, isPush, addingToView, changeListener);
-                        return true;
-                    }
-                });
+                onAnimationReadyOrAbortedListener = new OnAnimationReadyOrAbortedListener(container, from, to, isPush, true, changeListener);
+                to.getViewTreeObserver().addOnPreDrawListener(onAnimationReadyOrAbortedListener);
             }
         }
 
@@ -140,7 +140,7 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         }
     }
 
-    private void complete(@NonNull ControllerChangeCompletedListener changeListener, @Nullable AnimatorListener animatorListener) {
+    void complete(@NonNull ControllerChangeCompletedListener changeListener, @Nullable AnimatorListener animatorListener) {
         if (!completed) {
             completed = true;
             changeListener.onChangeCompleted();
@@ -150,16 +150,28 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
             if (animatorListener != null) {
                 animator.removeListener(animatorListener);
             }
-            animator.end();
+            animator.cancel();
             animator = null;
         }
+
+        onAnimationReadyOrAbortedListener = null;
     }
 
-    private void performAnimation(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, final boolean isPush, final boolean toAddedToContainer, @NonNull final ControllerChangeCompletedListener changeListener) {
+    void performAnimation(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, final boolean isPush, final boolean toAddedToContainer, @NonNull final ControllerChangeCompletedListener changeListener) {
         if (canceled) {
             complete(changeListener, null);
             return;
         }
+        if (needsImmediateCompletion) {
+            if (from != null && (!isPush || removesFromViewOnPush)) {
+                container.removeView(from);
+            }
+            complete(changeListener, null);
+            if (isPush && from != null) {
+                resetFromView(from);
+            }
+            return;
+        }
 
         animator = getAnimator(container, from, to, isPush, toAddedToContainer);
 
@@ -170,8 +182,12 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         animator.addListener(new AnimatorListenerAdapter() {
             @Override
             public void onAnimationCancel(Animator animation) {
-                if (from != null && (!isPush || removesFromViewOnPush) && needsImmediateCompletion) {
-                    container.removeView(from);
+                if (from != null) {
+                    resetFromView(from);
+                }
+
+                if (to != null && to.getParent() == container) {
+                    container.removeView(to);
                 }
 
                 complete(changeListener, this);
@@ -196,4 +212,46 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         animator.start();
     }
 
+    private class OnAnimationReadyOrAbortedListener implements ViewTreeObserver.OnPreDrawListener {
+        @NonNull final ViewGroup container;
+        @Nullable final View from;
+        @Nullable final View to;
+        final boolean isPush;
+        final boolean addingToView;
+        @NonNull final ControllerChangeCompletedListener changeListener;
+        private boolean hasRun;
+
+        OnAnimationReadyOrAbortedListener(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, boolean addingToView, @NonNull ControllerChangeCompletedListener changeListener) {
+            this.container = container;
+            this.from = from;
+            this.to = to;
+            this.isPush = isPush;
+            this.addingToView = addingToView;
+            this.changeListener = changeListener;
+        }
+
+        @Override
+        public boolean onPreDraw() {
+            onReadyOrAborted();
+
+            return true;
+        }
+
+        void onReadyOrAborted() {
+            if (!hasRun) {
+                hasRun = true;
+
+                if (to != null) {
+                    final ViewTreeObserver observer = to.getViewTreeObserver();
+                    if (observer.isAlive()) {
+                        observer.removeOnPreDrawListener(this);
+                    }
+                }
+
+                performAnimation(container, from, to, isPush, addingToView, changeListener);
+            }
+        }
+
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/AutoTransitionChangeHandler.java

@@ -1,30 +0,0 @@
-package com.bluelinelabs.conductor.changehandler;
-
-import android.annotation.TargetApi;
-import android.os.Build;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-import android.transition.AutoTransition;
-import android.transition.Transition;
-import android.view.View;
-import android.view.ViewGroup;
-
-import com.bluelinelabs.conductor.ControllerChangeHandler;
-
-/**
- * A change handler that will use an AutoTransition.
- */
-@TargetApi(Build.VERSION_CODES.LOLLIPOP)
-public class AutoTransitionChangeHandler extends TransitionChangeHandler {
-
-    @Override @NonNull
-    protected Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
-        return new AutoTransition();
-    }
-
-    @Override @NonNull
-    public ControllerChangeHandler copy() {
-        return new AutoTransitionChangeHandler();
-    }
-
-}

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/FadeChangeHandler.java

@@ -3,8 +3,8 @@ package com.bluelinelabs.conductor.changehandler;
 import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -32,11 +32,12 @@ public class FadeChangeHandler extends AnimatorChangeHandler {
     @Override @NonNull
     protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, boolean toAddedToContainer) {
         AnimatorSet animator = new AnimatorSet();
-        if (to != null && toAddedToContainer) {
-            animator.play(ObjectAnimator.ofFloat(to, View.ALPHA, 0, 1));
+        if (to != null) {
+            float start = toAddedToContainer ? 0 : to.getAlpha();
+            animator.play(ObjectAnimator.ofFloat(to, View.ALPHA, start, 1));
         }
 
-        if (from != null) {
+        if (from != null && (!isPush || removesFromViewOnPush())) {
             animator.play(ObjectAnimator.ofFloat(from, View.ALPHA, 0));
         }
 

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/HorizontalChangeHandler.java

@@ -3,8 +3,8 @@ package com.bluelinelabs.conductor.changehandler;
 import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -45,7 +45,9 @@ public class HorizontalChangeHandler extends AnimatorChangeHandler {
                 animatorSet.play(ObjectAnimator.ofFloat(from, View.TRANSLATION_X, from.getWidth()));
             }
             if (to != null) {
-                animatorSet.play(ObjectAnimator.ofFloat(to, View.TRANSLATION_X, -to.getWidth(), 0));
+                // Allow this to have a nice transition when coming off an aborted push animation
+                float fromLeft = from != null ? from.getTranslationX() : 0;
+                animatorSet.play(ObjectAnimator.ofFloat(to, View.TRANSLATION_X, fromLeft - to.getWidth(), 0));
             }
         }
 

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/SharedElementTransitionChangeHandler.java

@@ -0,0 +1,658 @@
+package com.bluelinelabs.conductor.changehandler;
+
+import android.annotation.TargetApi;
+import android.app.SharedElementCallback;
+import android.graphics.Rect;
+import android.os.Build;
+import android.transition.Transition;
+import android.transition.Transition.TransitionListener;
+import android.transition.TransitionSet;
+import android.util.ArrayMap;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.ViewTreeObserver;
+import android.view.ViewTreeObserver.OnPreDrawListener;
+
+import com.bluelinelabs.conductor.Controller;
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+import com.bluelinelabs.conductor.internal.LegacyTransitionUtils;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+/**
+ * A TransitionChangeHandler that facilitates using different Transitions for the entering view, the exiting view,
+ * and shared elements between the two.
+ *
+ * @deprecated See {@link TransitionChangeHandler}
+ */
+// Much of this class is based on FragmentTransition.java and FragmentTransitionCompat21.java from the Android support library
+@TargetApi(Build.VERSION_CODES.LOLLIPOP)
+@Deprecated
+public abstract class SharedElementTransitionChangeHandler extends TransitionChangeHandler {
+
+    // A map of from -> to names. Generally these will be the same.
+    @NonNull  final ArrayMap<String, String> sharedElementNames = new ArrayMap<>();
+
+    @NonNull  final List<String> waitForTransitionNames = new ArrayList<>();
+    @NonNull  final List<ViewParentPair> removedViews = new ArrayList<>();
+
+    @Nullable Transition exitTransition;
+    @Nullable Transition enterTransition;
+    @Nullable Transition sharedElementTransition;
+    @Nullable private SharedElementCallback exitTransitionCallback;
+    @Nullable private SharedElementCallback enterTransitionCallback;
+
+    @NonNull
+    @Override
+    protected final Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        exitTransition = getExitTransition(container, from, to, isPush);
+        enterTransition = getEnterTransition(container, from, to, isPush);
+        sharedElementTransition = getSharedElementTransition(container, from, to, isPush);
+        exitTransitionCallback = getExitTransitionCallback(container, from, to, isPush);
+        enterTransitionCallback = getEnterTransitionCallback(container, from, to, isPush);
+
+        if (enterTransition == null && sharedElementTransition == null && exitTransition == null) {
+            throw new IllegalStateException("SharedElementTransitionChangeHandler must have at least one transaction.");
+        }
+
+        return mergeTransitions(isPush);
+    }
+
+    @Override
+    public void prepareForTransition(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, @NonNull final Transition transition, final boolean isPush, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        OnTransitionPreparedListener listener = new OnTransitionPreparedListener() {
+            @Override
+            public void onPrepared() {
+                configureTransition(container, from, to, transition, isPush);
+                onTransitionPreparedListener.onPrepared();
+            }
+        };
+
+        configureSharedElements(container, from, to, isPush);
+
+        if (to != null && to.getParent() == null && waitForTransitionNames.size() > 0) {
+            waitOnAllTransitionNames(to, listener);
+            container.addView(to);
+        } else {
+            listener.onPrepared();
+        }
+    }
+
+    @Override
+    public final void executePropertyChanges(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @Nullable Transition transition, boolean isPush) {
+        if (to != null && removedViews.size() > 0) {
+            to.setVisibility(View.VISIBLE);
+
+            for (ViewParentPair removedView : removedViews) {
+                removedView.parent.addView(removedView.view);
+            }
+
+            removedViews.clear();
+        }
+
+        super.executePropertyChanges(container, from, to, transition, isPush);
+    }
+
+    @Override
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
+        super.onAbortPush(newHandler, newTop);
+
+        removedViews.clear();
+    }
+
+    void configureTransition(@NonNull final ViewGroup container, @Nullable View from, @Nullable View to, @NonNull final Transition transition, boolean isPush) {
+        final View nonExistentView = new View(container.getContext());
+
+        List<View> fromSharedElements = new ArrayList<>();
+        List<View> toSharedElements = new ArrayList<>();
+
+        configureSharedElements(container, nonExistentView, to, from, isPush, fromSharedElements, toSharedElements);
+
+        List<View> exitingViews = exitTransition != null ? configureEnteringExitingViews(exitTransition, from, fromSharedElements, nonExistentView) : null;
+        if (exitingViews == null || exitingViews.isEmpty()) {
+            exitTransition = null;
+        }
+
+        if (enterTransition != null) {
+            enterTransition.addTarget(nonExistentView);
+        }
+
+        final List<View> enteringViews = new ArrayList<>();
+        scheduleRemoveTargets(transition, enterTransition, enteringViews, exitTransition, exitingViews, sharedElementTransition, toSharedElements);
+        scheduleTargetChange(container, to, nonExistentView, toSharedElements, enteringViews, exitingViews);
+
+        setNameOverrides(container, toSharedElements);
+        scheduleNameReset(container, toSharedElements);
+    }
+
+    private void waitOnAllTransitionNames(@NonNull final View to, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        OnPreDrawListener onPreDrawListener = new OnPreDrawListener() {
+            boolean addedSubviewListeners;
+
+            @Override
+            public boolean onPreDraw() {
+                List<View> foundViews = new ArrayList<>();
+                boolean allViewsFound = true;
+                for (String transitionName : waitForTransitionNames) {
+                    View namedView = LegacyTransitionUtils.findNamedView(to, transitionName);
+                    if (namedView != null) {
+                        foundViews.add(LegacyTransitionUtils.findNamedView(to, transitionName));
+                    } else {
+                        allViewsFound = false;
+                        break;
+                    }
+                }
+
+                if (allViewsFound && !addedSubviewListeners) {
+                    addedSubviewListeners = true;
+                    waitOnChildTransitionNames(to, foundViews, this, onTransitionPreparedListener);
+                }
+
+                return false;
+            }
+        };
+
+        to.getViewTreeObserver().addOnPreDrawListener(onPreDrawListener);
+    }
+
+    void waitOnChildTransitionNames(@NonNull final View to, @NonNull List<View> foundViews, @NonNull final OnPreDrawListener parentPreDrawListener, @NonNull final OnTransitionPreparedListener onTransitionPreparedListener) {
+        for (final View view : foundViews) {
+            OneShotPreDrawListener.add(true, view, new Runnable() {
+                @Override
+                public void run() {
+                    waitForTransitionNames.remove(view.getTransitionName());
+
+                    removedViews.add(new ViewParentPair(view, (ViewGroup)view.getParent()));
+                    ((ViewGroup)view.getParent()).removeView(view);
+
+                    if (waitForTransitionNames.size() == 0) {
+                        to.getViewTreeObserver().removeOnPreDrawListener(parentPreDrawListener);
+                        to.setVisibility(View.INVISIBLE);
+                        onTransitionPreparedListener.onPrepared();
+                    }
+                }
+            });
+        }
+    }
+
+    private void scheduleTargetChange(@NonNull final ViewGroup container, @Nullable final View to, @NonNull final View nonExistentView,
+                                      @NonNull final List<View> toSharedElements, @NonNull final List<View> enteringViews, @Nullable final List<View> exitingViews) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                if (enterTransition != null) {
+                    enterTransition.removeTarget(nonExistentView);
+                    List<View> views = configureEnteringExitingViews(enterTransition, to, toSharedElements, nonExistentView);
+                    enteringViews.addAll(views);
+                }
+
+                if (exitingViews != null) {
+                    if (exitTransition != null) {
+                        List<View> tempExiting = new ArrayList<>();
+                        tempExiting.add(nonExistentView);
+                        LegacyTransitionUtils.replaceTargets(exitTransition, exitingViews, tempExiting);
+                    }
+                    exitingViews.clear();
+                    exitingViews.add(nonExistentView);
+                }
+            }
+        });
+    }
+
+    private Transition mergeTransitions(boolean isPush) {
+        boolean overlap = enterTransition == null || exitTransition == null || allowTransitionOverlap(isPush);
+
+        if (overlap) {
+            return LegacyTransitionUtils.mergeTransitions(TransitionSet.ORDERING_TOGETHER, exitTransition, enterTransition, sharedElementTransition);
+        } else {
+            Transition staggered = LegacyTransitionUtils.mergeTransitions(TransitionSet.ORDERING_SEQUENTIAL, exitTransition, enterTransition);
+            return LegacyTransitionUtils.mergeTransitions(TransitionSet.ORDERING_TOGETHER, staggered, sharedElementTransition);
+        }
+    }
+
+    @NonNull List<View> configureEnteringExitingViews(@NonNull Transition transition, @Nullable View view, @NonNull List<View> sharedElements, @NonNull View nonExistentView) {
+        List<View> viewList = new ArrayList<>();
+        if (view != null) {
+            captureTransitioningViews(viewList, view);
+        }
+        viewList.removeAll(sharedElements);
+        if (!viewList.isEmpty()) {
+            viewList.add(nonExistentView);
+            LegacyTransitionUtils.addTargets(transition, viewList);
+        }
+        return viewList;
+    }
+
+    private void configureSharedElements(@NonNull ViewGroup container, @NonNull final View nonExistentView, @Nullable final View to, @Nullable View from,
+                                         final boolean isPush, @NonNull final List<View> fromSharedElements, @NonNull final List<View> toSharedElements) {
+
+        if (to == null || from == null) {
+            return;
+        }
+
+        ArrayMap<String, View> capturedFromSharedElements = captureFromSharedElements(from);
+
+        if (sharedElementNames.isEmpty()) {
+            sharedElementTransition = null;
+        } else if (capturedFromSharedElements != null) {
+            fromSharedElements.addAll(capturedFromSharedElements.values());
+        }
+
+        if (enterTransition == null && exitTransition == null && sharedElementTransition == null) {
+            return;
+        }
+
+        callSharedElementStartEnd(capturedFromSharedElements, true);
+
+        final Rect toEpicenter;
+        if (sharedElementTransition != null) {
+            toEpicenter = new Rect();
+            LegacyTransitionUtils.setTargets(sharedElementTransition, nonExistentView, fromSharedElements);
+            setFromEpicenter(capturedFromSharedElements);
+            if (enterTransition != null) {
+                enterTransition.setEpicenterCallback(new Transition.EpicenterCallback() {
+                    @Override
+                    public Rect onGetEpicenter(Transition transition) {
+                        if (toEpicenter.isEmpty()) {
+                            return null;
+                        }
+                        return toEpicenter;
+                    }
+                });
+            }
+        } else {
+            toEpicenter = null;
+        }
+
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                ArrayMap<String, View> capturedToSharedElements = captureToSharedElements(to, isPush);
+
+                if (capturedToSharedElements != null) {
+                    toSharedElements.addAll(capturedToSharedElements.values());
+                    toSharedElements.add(nonExistentView);
+                }
+
+                callSharedElementStartEnd(capturedToSharedElements, false);
+                if (sharedElementTransition != null) {
+                    sharedElementTransition.getTargets().clear();
+                    sharedElementTransition.getTargets().addAll(toSharedElements);
+                    LegacyTransitionUtils.replaceTargets(sharedElementTransition, fromSharedElements, toSharedElements);
+
+                    final View toEpicenterView = getToEpicenterView(capturedToSharedElements);
+                    if (toEpicenterView != null && toEpicenter != null) {
+                        LegacyTransitionUtils.getBoundsOnScreen(toEpicenterView, toEpicenter);
+                    }
+                }
+            }
+        });
+    }
+
+    @Nullable View getToEpicenterView(@Nullable ArrayMap<String, View> toSharedElements) {
+        if (enterTransition != null && sharedElementNames.size() > 0 && toSharedElements != null) {
+            return toSharedElements.get(sharedElementNames.valueAt(0));
+        }
+        return null;
+    }
+
+    private void setFromEpicenter(@Nullable ArrayMap<String, View> fromSharedElements) {
+        if (sharedElementNames.size() > 0 && fromSharedElements != null) {
+            final View fromEpicenterView = fromSharedElements.get(sharedElementNames.keyAt(0));
+
+            if (sharedElementTransition != null) {
+                LegacyTransitionUtils.setEpicenter(sharedElementTransition, fromEpicenterView);
+            }
+
+            if (exitTransition != null) {
+                LegacyTransitionUtils.setEpicenter(exitTransition, fromEpicenterView);
+            }
+        }
+    }
+
+    @Nullable ArrayMap<String, View> captureToSharedElements(@Nullable final View to, boolean isPush) {
+        if (sharedElementNames.isEmpty() || sharedElementTransition == null || to == null) {
+            sharedElementNames.clear();
+            return null;
+        }
+
+        final ArrayMap<String, View> toSharedElements = new ArrayMap<>();
+        LegacyTransitionUtils.findNamedViews(toSharedElements, to);
+        for (ViewParentPair removedView : removedViews) {
+            toSharedElements.put(removedView.view.getTransitionName(), removedView.view);
+        }
+
+        final List<String> names = new ArrayList<>(sharedElementNames.values());
+
+        toSharedElements.retainAll(names);
+        if (enterTransitionCallback != null) {
+            enterTransitionCallback.onMapSharedElements(names, toSharedElements);
+            for (int i = names.size() - 1; i >= 0; i--) {
+                String name = names.get(i);
+                View view = toSharedElements.get(name);
+                if (view == null) {
+                    String key = findKeyForValue(sharedElementNames, name);
+                    if (key != null) {
+                        sharedElementNames.remove(key);
+                    }
+                } else if (!name.equals(view.getTransitionName())) {
+                    String key = findKeyForValue(sharedElementNames, name);
+                    if (key != null) {
+                        sharedElementNames.put(key, view.getTransitionName());
+                    }
+                }
+            }
+        } else {
+            for (int i = sharedElementNames.size() - 1; i >= 0; i--) {
+                final String targetName = sharedElementNames.valueAt(i);
+                if (!toSharedElements.containsKey(targetName)) {
+                    sharedElementNames.removeAt(i);
+                }
+            }
+        }
+        return toSharedElements;
+    }
+
+    @Nullable String findKeyForValue(@NonNull ArrayMap<String, String> map, @NonNull String value) {
+        final int numElements = map.size();
+        for (int i = 0; i < numElements; i++) {
+            if (value.equals(map.valueAt(i))) {
+                return map.keyAt(i);
+            }
+        }
+        return null;
+    }
+
+    @Nullable
+    private ArrayMap<String, View> captureFromSharedElements(@NonNull View from) {
+        if (sharedElementNames.isEmpty() || sharedElementTransition == null) {
+            sharedElementNames.clear();
+            return null;
+        }
+
+        final ArrayMap<String, View> fromSharedElements = new ArrayMap<>();
+        LegacyTransitionUtils.findNamedViews(fromSharedElements, from);
+
+        final List<String> names = new ArrayList<>(sharedElementNames.keySet());
+
+        fromSharedElements.retainAll(names);
+        if (exitTransitionCallback != null) {
+            exitTransitionCallback.onMapSharedElements(names, fromSharedElements);
+            for (int i = names.size() - 1; i >= 0; i--) {
+                String name = names.get(i);
+                View view = fromSharedElements.get(name);
+                if (view == null) {
+                    sharedElementNames.remove(name);
+                } else if (!name.equals(view.getTransitionName())) {
+                    String targetValue = sharedElementNames.remove(name);
+                    sharedElementNames.put(view.getTransitionName(), targetValue);
+                }
+            }
+        } else {
+            sharedElementNames.retainAll(fromSharedElements.keySet());
+        }
+        return fromSharedElements;
+    }
+
+    void callSharedElementStartEnd(@Nullable ArrayMap<String, View> sharedElements, boolean isStart) {
+        if (enterTransitionCallback != null) {
+            final int count = sharedElements == null ? 0 : sharedElements.size();
+            List<View> views = new ArrayList<>(count);
+            List<String> names = new ArrayList<>(count);
+            for (int i = 0; i < count; i++) {
+                names.add(sharedElements.keyAt(i));
+                views.add(sharedElements.valueAt(i));
+            }
+            if (isStart) {
+                enterTransitionCallback.onSharedElementStart(names, views, null);
+            } else {
+                enterTransitionCallback.onSharedElementEnd(names, views, null);
+            }
+        }
+    }
+
+    private void captureTransitioningViews(@NonNull List<View> transitioningViews, @NonNull View view) {
+        if (view.getVisibility() == View.VISIBLE) {
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                if (viewGroup.isTransitionGroup()) {
+                    transitioningViews.add(viewGroup);
+                } else {
+                    int count = viewGroup.getChildCount();
+                    for (int i = 0; i < count; i++) {
+                        View child = viewGroup.getChildAt(i);
+                        captureTransitioningViews(transitioningViews, child);
+                    }
+                }
+            } else {
+                transitioningViews.add(view);
+            }
+        }
+    }
+
+    private void scheduleRemoveTargets(@NonNull final Transition overallTransition,
+                                       @Nullable final Transition enterTransition, @Nullable final List<View> enteringViews,
+                                       @Nullable final Transition exitTransition, @Nullable final List<View> exitingViews,
+                                       @Nullable final Transition sharedElementTransition, @Nullable final List<View> toSharedElements) {
+        overallTransition.addListener(new TransitionListener() {
+            @Override
+            public void onTransitionStart(Transition transition) {
+                if (enterTransition != null && enteringViews != null) {
+                    LegacyTransitionUtils.replaceTargets(enterTransition, enteringViews, null);
+                }
+                if (exitTransition != null && exitingViews != null) {
+                    LegacyTransitionUtils.replaceTargets(exitTransition, exitingViews, null);
+                }
+                if (sharedElementTransition != null && toSharedElements != null) {
+                    LegacyTransitionUtils.replaceTargets(sharedElementTransition, toSharedElements, null);
+                }
+            }
+
+            @Override
+            public void onTransitionEnd(Transition transition) { }
+
+            @Override
+            public void onTransitionCancel(Transition transition) { }
+
+            @Override
+            public void onTransitionPause(Transition transition) { }
+
+            @Override
+            public void onTransitionResume(Transition transition) { }
+        });
+    }
+
+    private void setNameOverrides(@NonNull final View container, @NonNull final List<View> toSharedElements) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                final int numSharedElements = toSharedElements.size();
+                for (int i = 0; i < numSharedElements; i++) {
+                    View view = toSharedElements.get(i);
+                    String name = view.getTransitionName();
+                    if (name != null) {
+                        String inName = findKeyForValue(sharedElementNames, name);
+                        view.setTransitionName(inName);
+                    }
+                }
+            }
+        });
+    }
+
+    private void scheduleNameReset(@NonNull final ViewGroup container, @NonNull final List<View> toSharedElements) {
+        OneShotPreDrawListener.add(true, container, new Runnable() {
+            @Override
+            public void run() {
+                final int numSharedElements = toSharedElements.size();
+                for (int i = 0; i < numSharedElements; i++) {
+                    final View view = toSharedElements.get(i);
+                    final String name = view.getTransitionName();
+                    final String inName = sharedElementNames.get(name);
+                    view.setTransitionName(inName);
+                }
+            }
+        });
+    }
+
+    /**
+     * Will be called when views are ready to have their shared elements configured. Within this method one of the addSharedElement methods
+     * should be called for each shared element that will be used. If one or more of these shared elements will not instantly be available in
+     * the incoming view (for ex, in a RecyclerView), waitOnSharedElementNamed can be called to delay the transition until everything is available.
+     */
+    public abstract void configureSharedElements(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on the exiting ("from") view, if one is desired.
+     */
+    @Nullable
+    public abstract Transition getExitTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on shared elements between the from and to views.
+     */
+    @Nullable
+    public abstract Transition getSharedElementTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return the transition that will be used on the entering ("to") view, if one is desired.
+     */
+    @Nullable
+    public abstract Transition getEnterTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
+
+    /**
+     * Should return a callback that can be used to customize transition behavior of the shared element transition for the "from" view.
+     */
+    @Nullable
+    public SharedElementCallback getExitTransitionCallback(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        return null;
+    }
+
+    /**
+     * Should return a callback that can be used to customize transition behavior of the shared element transition for the "to" view.
+     */
+    @Nullable
+    public SharedElementCallback getEnterTransitionCallback(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
+        return null;
+    }
+
+    /**
+     * Should return whether or not the the exit transition and enter transition should overlap. If true,
+     * the enter transition will start as soon as possible. Otherwise, the enter transition will wait until the
+     * completion of the exit transition. Defaults to true.
+     */
+    public boolean allowTransitionOverlap(boolean isPush) {
+        return true;
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition.
+     *
+     * @param name The transition name that is used for both the entering and exiting views.
+     */
+    protected final void addSharedElement(@NonNull String name) {
+        sharedElementNames.put(name, name);
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition. Maps the name used in the
+     * "from" view to the name used in the "to" view if they are not the same.
+     *
+     * @param fromName The transition name used in the "from" view
+     * @param toName The transition name used in the "to" view
+     */
+    protected final void addSharedElement(@NonNull String fromName, @NonNull String toName) {
+        sharedElementNames.put(fromName, toName);
+    }
+
+    /**
+     * Used to register an element that will take part in the shared element transition. Maps the name used in the
+     * "from" view to the name used in the "to" view if they are not the same.
+     *
+     * @param sharedElement The view from the "from" view that will take part in the shared element transition
+     * @param toName The transition name used in the "to" view
+     */
+    protected final void addSharedElement(@NonNull View sharedElement, @NonNull String toName) {
+        String transitionName = sharedElement.getTransitionName();
+        if (transitionName == null) {
+            throw new IllegalArgumentException("Unique transitionNames are required for all sharedElements");
+        }
+        sharedElementNames.put(transitionName, toName);
+    }
+
+    /**
+     * The transition will be delayed until the view with the name passed in is available in the "to" hierarchy. This is
+     * particularly useful for views that don't load instantly, like RecyclerViews. Note that using this method can
+     * potentially lock up your app indefinitely if the view never loads!
+     */
+    protected final void waitOnSharedElementNamed(@NonNull String name) {
+        if (!sharedElementNames.values().contains(name)) {
+            throw new IllegalStateException("Can't wait on a shared element that hasn't been registered using addSharedElement");
+        }
+        waitForTransitionNames.add(name);
+    }
+
+    private static class OneShotPreDrawListener implements OnPreDrawListener, View.OnAttachStateChangeListener {
+
+        private final View view;
+        private ViewTreeObserver viewTreeObserver;
+        private final Runnable runnable;
+        private final boolean preDrawReturnValue;
+
+        private OneShotPreDrawListener(boolean preDrawReturnValue, @NonNull View view, @NonNull Runnable runnable) {
+            this.preDrawReturnValue = preDrawReturnValue;
+            this.view = view;
+            viewTreeObserver = view.getViewTreeObserver();
+            this.runnable = runnable;
+        }
+
+        @NonNull
+        public static OneShotPreDrawListener add(boolean preDrawReturnValue, @NonNull View view, @NonNull Runnable runnable) {
+            OneShotPreDrawListener listener = new OneShotPreDrawListener(preDrawReturnValue, view, runnable);
+            view.getViewTreeObserver().addOnPreDrawListener(listener);
+            view.addOnAttachStateChangeListener(listener);
+            return listener;
+        }
+
+        @Override
+        public boolean onPreDraw() {
+            removeListener();
+            runnable.run();
+            return preDrawReturnValue;
+        }
+
+        private void removeListener() {
+            if (viewTreeObserver.isAlive()) {
+                viewTreeObserver.removeOnPreDrawListener(this);
+            } else {
+                view.getViewTreeObserver().removeOnPreDrawListener(this);
+            }
+            view.removeOnAttachStateChangeListener(this);
+        }
+
+        @Override
+        public void onViewAttachedToWindow(View v) {
+            viewTreeObserver = v.getViewTreeObserver();
+        }
+
+        @Override
+        public void onViewDetachedFromWindow(View v) {
+            removeListener();
+        }
+
+    }
+
+    private static class ViewParentPair {
+        @NonNull final View view;
+        @NonNull final ViewGroup parent;
+
+        ViewParentPair(@NonNull View view, ViewGroup parent) {
+            this.view = view;
+            this.parent = parent;
+        }
+    }
+
+}

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/SimpleSwapChangeHandler.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor.changehandler;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.View.OnAttachStateChangeListener;
 import android.view.ViewGroup;

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/TransitionChangeHandler.java

@@ -2,8 +2,8 @@ package com.bluelinelabs.conductor.changehandler;
 
 import android.annotation.TargetApi;
 import android.os.Build;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.transition.Transition;
 import android.transition.Transition.TransitionListener;
 import android.transition.TransitionManager;
@@ -15,19 +15,31 @@ import com.bluelinelabs.conductor.ControllerChangeHandler;
 
 /**
  * A base {@link ControllerChangeHandler} that facilitates using {@link android.transition.Transition}s to replace Controller Views.
+ *
+ * @deprecated Transitions are backported via
+ * <a href="https://developer.android.com/jetpack/androidx/releases/transition">AndroidX</a>.
+ * They have the same API, but are preferred to the built-in framework transitions as they fix
+ * platform-specific bugs, and even work on versions older than 5.0.
+ * The {@code androidx-transition} module provides an equivalent {@link ControllerChangeHandler}.
  */
 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
+@Deprecated
 public abstract class TransitionChangeHandler extends ControllerChangeHandler {
 
-    private boolean canceled;
+    public interface OnTransitionPreparedListener {
+        void onPrepared();
+    }
+
+    boolean canceled;
+    private boolean needsImmediateCompletion;
 
     /**
      * Should be overridden to return the Transition to use while replacing Views.
      *
-     * @param container The container these Views are hosted in.
-     * @param from The previous View in the container, if any.
-     * @param to The next View that should be put in the container, if any.
-     * @param isPush True if this is a push transaction, false if it's a pop.
+     * @param container The container these Views are hosted in
+     * @param from      The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to        The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param isPush    True if this is a push transaction, false if it's a pop
      */
     @NonNull
     protected abstract Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
@@ -40,25 +52,52 @@ public abstract class TransitionChangeHandler extends ControllerChangeHandler {
     }
 
     @Override
-    public void performChange(@NonNull final ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
+    public void completeImmediately() {
+        super.completeImmediately();
+
+        needsImmediateCompletion = true;
+    }
+
+    @Nullable
+    private ControllerChangeCompletedListener listener;
+
+    @Override
+    public void performChange(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, final boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
+        listener = changeListener;
         if (canceled) {
             changeListener.onChangeCompleted();
             return;
         }
+        if (needsImmediateCompletion) {
+            executePropertyChanges(container, from, to, null, isPush);
+            changeListener.onChangeCompleted();
+            return;
+        }
 
-        Transition transition = getTransition(container, from, to, isPush);
+        final Runnable onTransitionNotStarted = new Runnable() {
+            @Override
+            public void run() {
+                changeListener.onChangeCompleted();
+            }
+        };
+
+        final Transition transition = getTransition(container, from, to, isPush);
         transition.addListener(new TransitionListener() {
             @Override
-            public void onTransitionStart(Transition transition) { }
+            public void onTransitionStart(Transition transition) {
+                container.removeCallbacks(onTransitionNotStarted);
+            }
 
             @Override
             public void onTransitionEnd(Transition transition) {
-                changeListener.onChangeCompleted();
+                listener.onChangeCompleted();
+                listener = null;
             }
 
             @Override
             public void onTransitionCancel(Transition transition) {
-                changeListener.onChangeCompleted();
+                listener.onChangeCompleted();
+                listener = null;
             }
 
             @Override
@@ -68,8 +107,49 @@ public abstract class TransitionChangeHandler extends ControllerChangeHandler {
             public void onTransitionResume(Transition transition) { }
         });
 
-        TransitionManager.beginDelayedTransition(container, transition);
-        if (from != null) {
+        prepareForTransition(container, from, to, transition, isPush, new OnTransitionPreparedListener() {
+            @Override
+            public void onPrepared() {
+                if (!canceled) {
+                    TransitionManager.beginDelayedTransition(container, transition);
+                    executePropertyChanges(container, from, to, transition, isPush);
+                    container.post(onTransitionNotStarted);
+                }
+            }
+        });
+    }
+
+    @Override
+    public boolean removesFromViewOnPush() {
+        return true;
+    }
+
+    /**
+     * Called before a transition occurs. This can be used to reorder views, set their transition names, etc. The transition will begin
+     * when {@code onTransitionPreparedListener} is called.
+     *
+     * @param container  The container these Views are hosted in
+     * @param from       The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to         The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param transition The transition that is being prepared for
+     * @param isPush     True if this is a push transaction, false if it's a pop
+     */
+    public void prepareForTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @NonNull Transition transition, boolean isPush, @NonNull OnTransitionPreparedListener onTransitionPreparedListener) {
+        onTransitionPreparedListener.onPrepared();
+    }
+
+    /**
+     * This should set all view properties needed for the transition to work properly. By default it removes the "from" view
+     * and adds the "to" view.
+     *
+     * @param container  The container these Views are hosted in
+     * @param from       The previous View in the container or {@code null} if there was no Controller before this transition
+     * @param to         The next View that should be put in the container or {@code null} if no Controller is being transitioned to
+     * @param transition The transition with which {@code TransitionManager.beginDelayedTransition} has been called. This will be null only if another ControllerChangeHandler immediately overrides this one.
+     * @param isPush     True if this is a push transaction, false if it's a pop
+     */
+    public void executePropertyChanges(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, @Nullable Transition transition, boolean isPush) {
+        if (from != null && (removesFromViewOnPush() || !isPush) && from.getParent() == container) {
             container.removeView(from);
         }
         if (to != null && to.getParent() == null) {
@@ -77,9 +157,4 @@ public abstract class TransitionChangeHandler extends ControllerChangeHandler {
         }
     }
 
-    @Override
-    public final boolean removesFromViewOnPush() {
-        return true;
-    }
-
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/TransitionChangeHandlerCompat.java

@@ -2,11 +2,12 @@ package com.bluelinelabs.conductor.changehandler;
 
 import android.os.Build;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.Controller;
 import com.bluelinelabs.conductor.ControllerChangeHandler;
 import com.bluelinelabs.conductor.internal.ClassUtils;
 
@@ -19,6 +20,7 @@ public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
     private static final String KEY_CHANGE_HANDLER_CLASS = "TransitionChangeHandlerCompat.changeHandler.class";
     private static final String KEY_HANDLER_STATE = "TransitionChangeHandlerCompat.changeHandler.state";
 
+    @Nullable 
     private ControllerChangeHandler changeHandler;
 
     public TransitionChangeHandlerCompat() { }
@@ -40,17 +42,23 @@ public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
 
     @Override
     public void performChange(@NonNull final ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
-        changeHandler.performChange(container, from, to, isPush, changeListener);
+        if (changeHandler != null) {
+            changeHandler.performChange(container, from, to, isPush, changeListener);
+        }
     }
 
     @Override
     public void saveToBundle(@NonNull Bundle bundle) {
         super.saveToBundle(bundle);
 
-        bundle.putString(KEY_CHANGE_HANDLER_CLASS, changeHandler.getClass().getName());
+        if (changeHandler != null) {
+            bundle.putString(KEY_CHANGE_HANDLER_CLASS, changeHandler.getClass().getName());
+        }
 
         Bundle stateBundle = new Bundle();
-        changeHandler.saveToBundle(stateBundle);
+        if (changeHandler != null) {
+            changeHandler.saveToBundle(stateBundle);
+        }
         bundle.putBundle(KEY_HANDLER_STATE, stateBundle);
     }
 
@@ -66,7 +74,10 @@ public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
 
     @Override
     public boolean removesFromViewOnPush() {
-        return changeHandler.removesFromViewOnPush();
+        if (changeHandler != null) {
+            return changeHandler.removesFromViewOnPush();
+        }
+        return true;
     }
 
     @Override @NonNull
@@ -78,4 +89,29 @@ public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
         }
     }
 
+    @Override
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
+        if (changeHandler != null) {
+            changeHandler.onAbortPush(newHandler, newTop);
+        }
+    }
+
+    @Override
+    public void completeImmediately() {
+      if (changeHandler != null) {
+        changeHandler.completeImmediately();
+      }
+    }
+
+    @Override
+    public void setForceRemoveViewOnPush(boolean force) {
+      if (changeHandler != null) {
+        changeHandler.setForceRemoveViewOnPush(force);
+      }
+    }
+
+    @Override 
+    protected void onEnd() {
+        changeHandler = null;
+    }
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/VerticalChangeHandler.java

@@ -3,8 +3,8 @@ package com.bluelinelabs.conductor.changehandler;
 import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 

conductor/src/main/java/com/bluelinelabs/conductor/internal/ClassUtils.java

@@ -1,7 +1,7 @@
 package com.bluelinelabs.conductor.internal;
 
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.text.TextUtils;
 
 public class ClassUtils {

conductor/src/main/java/com/bluelinelabs/conductor/internal/LegacyTransitionUtils.java

@@ -0,0 +1,185 @@
+package com.bluelinelabs.conductor.internal;
+
+import android.annotation.TargetApi;
+import android.graphics.Rect;
+import android.os.Build;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import android.transition.Transition;
+import android.transition.TransitionSet;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.List;
+import java.util.Map;
+
+@TargetApi(Build.VERSION_CODES.LOLLIPOP)
+public class LegacyTransitionUtils {
+
+    public static void findNamedViews(@NonNull Map<String, View> namedViews, View view) {
+        if (view.getVisibility() == View.VISIBLE) {
+            String transitionName = view.getTransitionName();
+            if (transitionName != null) {
+                namedViews.put(transitionName, view);
+            }
+
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                int childCount = viewGroup.getChildCount();
+                for (int i = 0; i < childCount; i++) {
+                    View child = viewGroup.getChildAt(i);
+                    findNamedViews(namedViews, child);
+                }
+            }
+        }
+    }
+
+    @Nullable
+    public static View findNamedView(@NonNull View view, @NonNull String transitionName) {
+        if (transitionName.equals(view.getTransitionName())) {
+            return view;
+        }
+
+        if (view instanceof ViewGroup) {
+            ViewGroup viewGroup = (ViewGroup) view;
+            int childCount = viewGroup.getChildCount();
+            for (int i = 0; i < childCount; i++) {
+                View viewWithTransitionName = findNamedView(viewGroup.getChildAt(i), transitionName);
+                if (viewWithTransitionName != null) {
+                    return viewWithTransitionName;
+                }
+            }
+        }
+
+        return null;
+    }
+
+    public static void setEpicenter(@NonNull Transition transition, @Nullable View view) {
+        if (view != null) {
+            final Rect epicenter = new Rect();
+            getBoundsOnScreen(view, epicenter);
+            transition.setEpicenterCallback(new Transition.EpicenterCallback() {
+                @Override
+                public Rect onGetEpicenter(Transition transition) {
+                    return epicenter;
+                }
+            });
+        }
+    }
+
+    public static void getBoundsOnScreen(@NonNull View view, @NonNull Rect epicenter) {
+        int[] loc = new int[2];
+        view.getLocationOnScreen(loc);
+        epicenter.set(loc[0], loc[1], loc[0] + view.getWidth(), loc[1] + view.getHeight());
+    }
+
+    public static void setTargets(@NonNull Transition transition, @NonNull View nonExistentView, @NonNull List<View> sharedViews) {
+        final List<View> views = transition.getTargets();
+        views.clear();
+        final int count = sharedViews.size();
+        for (int i = 0; i < count; i++) {
+            final View view = sharedViews.get(i);
+            bfsAddViewChildren(views, view);
+        }
+        views.add(nonExistentView);
+        sharedViews.add(nonExistentView);
+        addTargets(transition, sharedViews);
+    }
+
+    public static void addTargets(@Nullable Transition transition, @NonNull List<View> views) {
+        if (transition == null) {
+            return;
+        }
+        if (transition instanceof TransitionSet) {
+            TransitionSet set = (TransitionSet) transition;
+            int numTransitions = set.getTransitionCount();
+            for (int i = 0; i < numTransitions; i++) {
+                Transition child = set.getTransitionAt(i);
+                addTargets(child, views);
+            }
+        } else if (!hasSimpleTarget(transition)) {
+            List<View> targets = transition.getTargets();
+            if (isNullOrEmpty(targets)) {
+                int numViews = views.size();
+                for (int i = 0; i < numViews; i++) {
+                    transition.addTarget(views.get(i));
+                }
+            }
+        }
+    }
+
+    public static void replaceTargets(@NonNull Transition transition, @NonNull List<View> oldTargets, @Nullable List<View> newTargets) {
+        if (transition instanceof TransitionSet) {
+            TransitionSet set = (TransitionSet) transition;
+            int numTransitions = set.getTransitionCount();
+            for (int i = 0; i < numTransitions; i++) {
+                Transition child = set.getTransitionAt(i);
+                replaceTargets(child, oldTargets, newTargets);
+            }
+        } else if (!LegacyTransitionUtils.hasSimpleTarget(transition)) {
+            List<View> targets = transition.getTargets();
+            if (targets != null && targets.size() == oldTargets.size() && targets.containsAll(oldTargets)) {
+                final int targetCount = newTargets == null ? 0 : newTargets.size();
+                for (int i = 0; i < targetCount; i++) {
+                    transition.addTarget(newTargets.get(i));
+                }
+                for (int i = oldTargets.size() - 1; i >= 0; i--) {
+                    transition.removeTarget(oldTargets.get(i));
+                }
+            }
+        }
+    }
+
+    private static void bfsAddViewChildren(@NonNull final List<View> views, @NonNull final View startView) {
+        final int startIndex = views.size();
+        if (containedBeforeIndex(views, startView, startIndex)) {
+            return; // This child is already in the list, so all its children are also.
+        }
+        views.add(startView);
+        for (int index = startIndex; index < views.size(); index++) {
+            final View view = views.get(index);
+            if (view instanceof ViewGroup) {
+                ViewGroup viewGroup = (ViewGroup) view;
+                final int childCount = viewGroup.getChildCount();
+                for (int childIndex = 0; childIndex < childCount; childIndex++) {
+                    final View child = viewGroup.getChildAt(childIndex);
+                    if (!containedBeforeIndex(views, child, startIndex)) {
+                        views.add(child);
+                    }
+                }
+            }
+        }
+    }
+
+    private static boolean containedBeforeIndex(@NonNull List<View> views, View view, int maxIndex) {
+        for (int i = 0; i < maxIndex; i++) {
+            if (views.get(i) == view) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static boolean hasSimpleTarget(@NonNull Transition transition) {
+        return !isNullOrEmpty(transition.getTargetIds())
+                || !isNullOrEmpty(transition.getTargetNames())
+                || !isNullOrEmpty(transition.getTargetTypes());
+    }
+
+    private static boolean isNullOrEmpty(@Nullable List list) {
+        return list == null || list.isEmpty();
+    }
+
+    @NonNull
+    public static TransitionSet mergeTransitions(int ordering, Transition... transitions) {
+        TransitionSet transitionSet = new TransitionSet();
+        for (Transition transition : transitions) {
+            if (transition != null) {
+                transitionSet.addTransition(transition);
+            }
+        }
+        transitionSet.setOrdering(ordering);
+        return transitionSet;
+    }
+
+}

conductor/src/main/java/com/bluelinelabs/conductor/internal/LifecycleHandler.java

@@ -6,12 +6,11 @@ import android.app.Application.ActivityLifecycleCallbacks;
 import android.app.Fragment;
 import android.content.Context;
 import android.content.Intent;
+import android.content.IntentSender;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
 import android.util.SparseArray;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -26,6 +25,9 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 public class LifecycleHandler extends Fragment implements ActivityLifecycleCallbacks {
 
     private static final String FRAGMENT_TAG = "LifecycleHandler";
@@ -39,7 +41,9 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     private boolean hasRegisteredCallbacks;
     private boolean destroyed;
     private boolean attached;
+    private boolean hasPreparedForHostDetach;
 
+    private static final Map<Activity, LifecycleHandler> activeLifecycleHandlers = new HashMap<>();
     private SparseArray<String> permissionRequestMap = new SparseArray<>();
     private SparseArray<String> activityRequestMap = new SparseArray<>();
     private ArrayList<PendingPermissionRequest> pendingPermissionRequests = new ArrayList<>();
@@ -53,7 +57,10 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
     @Nullable
     private static LifecycleHandler findInActivity(@NonNull Activity activity) {
-        LifecycleHandler lifecycleHandler = (LifecycleHandler)activity.getFragmentManager().findFragmentByTag(FRAGMENT_TAG);
+        LifecycleHandler lifecycleHandler = activeLifecycleHandlers.get(activity);
+        if (lifecycleHandler == null) {
+            lifecycleHandler = (LifecycleHandler)activity.getFragmentManager().findFragmentByTag(FRAGMENT_TAG);
+        }
         if (lifecycleHandler != null) {
             lifecycleHandler.registerActivityListener(activity);
         }
@@ -112,6 +119,11 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         if (!hasRegisteredCallbacks) {
             hasRegisteredCallbacks = true;
             activity.getApplication().registerActivityLifecycleCallbacks(this);
+
+            // Since Fragment transactions are async, we have to keep an <Activity, LifecycleHandler> map in addition
+            // to trying to find the LifecycleHandler fragment in the Activity to handle the case of the developer
+            // trying to immediately get > 1 router in the same Activity. See issue #299.
+            activeLifecycleHandlers.put(activity, this);
         }
     }
 
@@ -146,6 +158,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
         if (activity != null) {
             activity.getApplication().unregisterActivityLifecycleCallbacks(this);
+            activeLifecycleHandlers.remove(activity);
             destroyRouters();
             activity = null;
         }
@@ -183,6 +196,10 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
                 requestPermissions(request.instanceId, request.permissions, request.requestCode);
             }
         }
+
+        for (ActivityHostedRouter router : new ArrayList<>(routerMap.values())) {
+            router.onContextAvailable();
+        }
     }
 
     private void destroyRouters() {
@@ -190,7 +207,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
             destroyed = true;
 
             if (activity != null) {
-                for (Router router : routerMap.values()) {
+                for (Router router : getRouters()) {
                     router.onActivityDestroyed(activity);
                 }
             }
@@ -203,7 +220,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
         String instanceId = activityRequestMap.get(requestCode);
         if (instanceId != null) {
-            for (Router router : routerMap.values()) {
+            for (Router router : getRouters()) {
                 router.onActivityResult(instanceId, requestCode, resultCode, data);
             }
         }
@@ -215,7 +232,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
         String instanceId = permissionRequestMap.get(requestCode);
         if (instanceId != null) {
-            for (Router router : routerMap.values()) {
+            for (Router router : getRouters()) {
                 router.onRequestPermissionsResult(instanceId, requestCode, permissions, grantResults);
             }
         }
@@ -223,7 +240,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
     @Override
     public boolean shouldShowRequestPermissionRationale(@NonNull String permission) {
-        for (Router router : routerMap.values()) {
+        for (Router router : getRouters()) {
             Boolean handled = router.handleRequestedPermission(permission);
             if (handled != null) {
                 return handled;
@@ -236,7 +253,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
         super.onCreateOptionsMenu(menu, inflater);
 
-        for (Router router : routerMap.values()) {
+        for (Router router : getRouters()) {
             router.onCreateOptionsMenu(menu, inflater);
         }
     }
@@ -245,14 +262,14 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     public void onPrepareOptionsMenu(Menu menu) {
         super.onPrepareOptionsMenu(menu);
 
-        for (Router router : routerMap.values()) {
+        for (Router router : getRouters()) {
             router.onPrepareOptionsMenu(menu);
         }
     }
 
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
-        for (Router router : routerMap.values()) {
+        for (Router router : getRouters()) {
             if (router.onOptionsItemSelected(item)) {
                 return true;
             }
@@ -283,6 +300,14 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         startActivityForResult(intent, requestCode, options);
     }
 
+    @TargetApi(Build.VERSION_CODES.N)
+    public void startIntentSenderForResult(@NonNull String instanceId, @NonNull IntentSender intent, int requestCode,
+                                           @Nullable Intent fillInIntent, int flagsMask, int flagsValues, int extraFlags,
+                                           @Nullable Bundle options) throws IntentSender.SendIntentException {
+        registerForActivityResult(instanceId, requestCode);
+        startIntentSenderForResult(intent, requestCode, fillInIntent, flagsMask, flagsValues, extraFlags, options);
+    }
+
     @TargetApi(Build.VERSION_CODES.M)
     public void requestPermissions(@NonNull String instanceId, @NonNull String[] permissions, int requestCode) {
         if (attached) {
@@ -297,13 +322,19 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
         if (this.activity == null && findInActivity(activity) == LifecycleHandler.this) {
             this.activity = activity;
+
+            for (ActivityHostedRouter router : new ArrayList<>(routerMap.values())) {
+                router.onContextAvailable();
+            }
         }
     }
 
     @Override
     public void onActivityStarted(Activity activity) {
         if (this.activity == activity) {
-            for (Router router : routerMap.values()) {
+            hasPreparedForHostDetach = false;
+
+            for (Router router : getRouters()) {
                 router.onActivityStarted(activity);
             }
         }
@@ -312,7 +343,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     @Override
     public void onActivityResumed(Activity activity) {
         if (this.activity == activity) {
-            for (Router router : routerMap.values()) {
+            for (Router router : getRouters()) {
                 router.onActivityResumed(activity);
             }
         }
@@ -321,7 +352,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     @Override
     public void onActivityPaused(Activity activity) {
         if (this.activity == activity) {
-            for (Router router : routerMap.values()) {
+            for (Router router : getRouters()) {
                 router.onActivityPaused(activity);
             }
         }
@@ -330,7 +361,9 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     @Override
     public void onActivityStopped(Activity activity) {
         if (this.activity == activity) {
-            for (Router router : routerMap.values()) {
+            prepareForHostDetachIfNeeded();
+
+            for (Router router : getRouters()) {
                 router.onActivityStopped(activity);
             }
         }
@@ -339,7 +372,9 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     @Override
     public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
         if (this.activity == activity) {
-            for (Router router : routerMap.values()) {
+            prepareForHostDetachIfNeeded();
+
+            for (Router router : getRouters()) {
                 Bundle bundle = new Bundle();
                 router.saveInstanceState(bundle);
                 outState.putBundle(KEY_ROUTER_STATE_PREFIX + router.getContainerId(), bundle);
@@ -348,7 +383,19 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     }
 
     @Override
-    public void onActivityDestroyed(Activity activity) { }
+    public void onActivityDestroyed(Activity activity) {
+        activeLifecycleHandlers.remove(activity);
+    }
+
+    private void prepareForHostDetachIfNeeded() {
+        if (!hasPreparedForHostDetach) {
+            hasPreparedForHostDetach = true;
+
+            for (Router router : getRouters()) {
+                router.prepareForHostDetach();
+            }
+        }
+    }
 
     private static class PendingPermissionRequest implements Parcelable {
         final String instanceId;
@@ -361,7 +408,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
             this.requestCode = requestCode;
         }
 
-        private PendingPermissionRequest(Parcel in) {
+        PendingPermissionRequest(Parcel in) {
             instanceId = in.readString();
             permissions = in.createStringArray();
             requestCode = in.readInt();

conductor/src/main/java/com/bluelinelabs/conductor/internal/NoOpControllerChangeHandler.java

@@ -1,7 +1,7 @@
 package com.bluelinelabs.conductor.internal;
 
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -24,4 +24,4 @@ public class NoOpControllerChangeHandler extends ControllerChangeHandler {
     public boolean isReusable() {
         return true;
     }
-}
+}

conductor/src/main/java/com/bluelinelabs/conductor/internal/StringSparseArrayParceler.java

@@ -2,7 +2,7 @@ package com.bluelinelabs.conductor.internal;
 
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 import android.util.SparseArray;
 
 public class StringSparseArrayParceler implements Parcelable {
@@ -13,7 +13,7 @@ public class StringSparseArrayParceler implements Parcelable {
         this.stringSparseArray = stringSparseArray;
     }
 
-    private StringSparseArrayParceler(@NonNull Parcel in) {
+    StringSparseArrayParceler(@NonNull Parcel in) {
         stringSparseArray = new SparseArray<>();
 
         final int size = in.readInt();

conductor/src/main/java/com/bluelinelabs/conductor/internal/ThreadUtils.java

@@ -0,0 +1,20 @@
+package com.bluelinelabs.conductor.internal;
+
+import android.os.Looper;
+import android.util.AndroidRuntimeException;
+
+public class ThreadUtils {
+
+    public static void ensureMainThread() {
+        if (Looper.getMainLooper().getThread() != Thread.currentThread()) {
+            throw new CalledFromWrongThreadException("Methods that affect the view hierarchy can can only be called from the main thread.");
+        }
+    }
+
+    private static final class CalledFromWrongThreadException extends AndroidRuntimeException {
+        CalledFromWrongThreadException(String msg) {
+            super(msg);
+        }
+    }
+
+}

conductor/src/main/java/com/bluelinelabs/conductor/internal/TransactionIndexer.java

@@ -0,0 +1,24 @@
+package com.bluelinelabs.conductor.internal;
+
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+
+public class TransactionIndexer {
+
+    private static final String KEY_INDEX = "TransactionIndexer.currentIndex";
+
+    private int currentIndex;
+
+    public int nextIndex() {
+        return ++currentIndex;
+    }
+
+    public void saveInstanceState(@NonNull Bundle outState) {
+        outState.putInt(KEY_INDEX, currentIndex);
+    }
+
+    public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
+        currentIndex = savedInstanceState.getInt(KEY_INDEX);
+    }
+
+}

conductor/src/main/java/com/bluelinelabs/conductor/internal/ViewAttachHandler.java

@@ -4,67 +4,107 @@ import android.view.View;
 import android.view.View.OnAttachStateChangeListener;
 import android.view.ViewGroup;
 
-public class ViewAttachHandler {
+public class ViewAttachHandler implements OnAttachStateChangeListener {
+
+    private enum ReportedState {
+        VIEW_DETACHED,
+        ACTIVITY_STOPPED,
+        ATTACHED
+    }
 
     public interface ViewAttachListener {
-        void onAttached(View view);
-        void onDetached(View view);
+        void onAttached();
+        void onDetached(boolean fromActivityStop);
+        void onViewDetachAfterStop();
     }
 
     private interface ChildAttachListener {
         void onAttached();
     }
 
+    private boolean rootAttached = false;
+    boolean childrenAttached = false;
+    private boolean activityStopped = false;
+    private ReportedState reportedState = ReportedState.VIEW_DETACHED;
     private ViewAttachListener attachListener;
-    private OnAttachStateChangeListener rootOnAttachStateChangeListener = new OnAttachStateChangeListener() {
-        boolean rootAttached = false;
-        boolean childrenAttached = false;
-
-        @Override
-        public void onViewAttachedToWindow(final View v) {
-            if (rootAttached) {
-                return;
-            }
-
-            rootAttached = true;
-            listenForDeepestChildAttach(v, new ChildAttachListener() {
-                @Override
-                public void onAttached() {
-                    childrenAttached = true;
-                    attachListener.onAttached(v);
-                }
-            });
-
-        }
-
-        @Override
-        public void onViewDetachedFromWindow(View v) {
-            rootAttached = false;
-            if (childrenAttached) {
-                childrenAttached = false;
-                attachListener.onDetached(v);
-            }
-        }
-    };
-    private OnAttachStateChangeListener childOnAttachStateChangeListener;
+    OnAttachStateChangeListener childOnAttachStateChangeListener;
 
     public ViewAttachHandler(ViewAttachListener attachListener) {
         this.attachListener = attachListener;
     }
 
+    @Override
+    public void onViewAttachedToWindow(final View v) {
+        if (rootAttached) {
+            return;
+        }
+
+        rootAttached = true;
+        listenForDeepestChildAttach(v, new ChildAttachListener() {
+            @Override
+            public void onAttached() {
+                childrenAttached = true;
+                reportAttached();
+
+            }
+        });
+    }
+
+    @Override
+    public void onViewDetachedFromWindow(View v) {
+        rootAttached = false;
+        if (childrenAttached) {
+            childrenAttached = false;
+            reportDetached(false);
+        }
+    }
+
     public void listenForAttach(final View view) {
-        view.addOnAttachStateChangeListener(rootOnAttachStateChangeListener);
+        view.addOnAttachStateChangeListener(this);
     }
 
     public void unregisterAttachListener(View view) {
-        view.removeOnAttachStateChangeListener(rootOnAttachStateChangeListener);
+        view.removeOnAttachStateChangeListener(this);
 
         if (childOnAttachStateChangeListener != null && view instanceof ViewGroup) {
             findDeepestChild((ViewGroup)view).removeOnAttachStateChangeListener(childOnAttachStateChangeListener);
         }
     }
 
-    void listenForDeepestChildAttach(final View view, final ChildAttachListener attachListener) {
+    public void onActivityStarted() {
+        activityStopped = false;
+        reportAttached();
+    }
+
+    public void onActivityStopped() {
+        activityStopped = true;
+        reportDetached(true);
+    }
+
+    void reportAttached() {
+        if (rootAttached && childrenAttached && !activityStopped && reportedState != ReportedState.ATTACHED) {
+            reportedState = ReportedState.ATTACHED;
+            attachListener.onAttached();
+        }
+    }
+
+    private void reportDetached(boolean detachedForActivity) {
+        boolean wasDetachedForActivity = reportedState == ReportedState.ACTIVITY_STOPPED;
+
+        if (detachedForActivity) {
+            reportedState = ReportedState.ACTIVITY_STOPPED;
+        } else {
+            reportedState = ReportedState.VIEW_DETACHED;
+        }
+
+        if (wasDetachedForActivity && !detachedForActivity) {
+            attachListener.onViewDetachAfterStop();
+        } else {
+            attachListener.onDetached(detachedForActivity);
+        }
+    }
+
+    private void listenForDeepestChildAttach(final View view, final ChildAttachListener attachListener) {
         if (!(view instanceof ViewGroup)) {
             attachListener.onAttached();
             return;

conductor/src/test/java/com/bluelinelabs/conductor/ControllerLifecycleActivityReferenceTests.java

@@ -0,0 +1,269 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.bluelinelabs.conductor.util.ActivityProxy;
+import com.bluelinelabs.conductor.util.MockChangeHandler;
+import com.bluelinelabs.conductor.util.TestController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class ControllerLifecycleActivityReferenceTests {
+
+    private Router router;
+
+    private ActivityProxy activityProxy;
+
+    public void createActivityController(Bundle savedInstanceState, boolean includeStartAndResume) {
+        activityProxy = new ActivityProxy().create(savedInstanceState);
+
+        if (includeStartAndResume) {
+            activityProxy.start().resume();
+        }
+
+        router = Conductor.attachRouter(activityProxy.getActivity(), activityProxy.getView(), savedInstanceState);
+        router.setPopsLastView(true);
+        if (!router.hasRootController()) {
+            router.setRoot(RouterTransaction.with(new TestController()));
+        }
+    }
+
+    @Before
+    public void setup() {
+        createActivityController(null, true);
+    }
+
+    @Test
+    public void testSingleControllerActivityOnPush() {
+        Controller controller = new TestController();
+
+        assertNull(controller.getActivity());
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        controller.addLifecycleListener(listener);
+
+        router.pushController(RouterTransaction.with(controller)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        assertEquals(Collections.singletonList(true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.emptyList(), listener.postDetachReferences);
+        assertEquals(Collections.emptyList(), listener.postDestroyViewReferences);
+        assertEquals(Collections.emptyList(), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testChildControllerActivityOnPush() {
+        Controller parent = new TestController();
+        router.pushController(RouterTransaction.with(parent)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        TestController child = new TestController();
+
+        assertNull(child.getActivity());
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        child.addLifecycleListener(listener);
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter.pushController(RouterTransaction.with(child)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        assertEquals(Collections.singletonList(true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.emptyList(), listener.postDetachReferences);
+        assertEquals(Collections.emptyList(), listener.postDestroyViewReferences);
+        assertEquals(Collections.emptyList(), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testSingleControllerActivityOnPop() {
+        Controller controller = new TestController();
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        controller.addLifecycleListener(listener);
+
+        router.pushController(RouterTransaction.with(controller)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        router.popCurrentController();
+
+        assertEquals(Arrays.asList(true, true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDetachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testChildControllerActivityOnPop() {
+        Controller parent = new TestController();
+
+        router.pushController(RouterTransaction.with(parent)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        TestController child = new TestController();
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        child.addLifecycleListener(listener);
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
+        childRouter.pushController(RouterTransaction.with(child)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        childRouter.popCurrentController();
+
+        assertEquals(Arrays.asList(true, true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDetachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testChildControllerActivityOnParentPop() {
+        Controller parent = new TestController();
+
+        router.pushController(RouterTransaction.with(parent)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        TestController child = new TestController();
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        child.addLifecycleListener(listener);
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
+        childRouter.pushController(RouterTransaction.with(child)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        router.popCurrentController();
+
+        assertEquals(Collections.singletonList(true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDetachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testSingleControllerActivityOnDestroy() {
+        Controller controller = new TestController();
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        controller.addLifecycleListener(listener);
+
+        router.pushController(RouterTransaction.with(controller)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        activityProxy.pause().stop(false).destroy();
+
+        assertEquals(Collections.singletonList(true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDetachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyReferences);
+    }
+
+    @Test
+    public void testChildControllerActivityOnDestroy() {
+        Controller parent = new TestController();
+
+        router.pushController(RouterTransaction.with(parent)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        TestController child = new TestController();
+
+        ActivityReferencingLifecycleListener listener = new ActivityReferencingLifecycleListener();
+        child.addLifecycleListener(listener);
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
+        childRouter.pushController(RouterTransaction.with(child)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        activityProxy.pause().stop(false).destroy();
+
+        assertEquals(Collections.singletonList(true), listener.changeEndReferences);
+        assertEquals(Collections.singletonList(true), listener.postCreateViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postAttachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDetachReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyViewReferences);
+        assertEquals(Collections.singletonList(true), listener.postDestroyReferences);
+    }
+
+    static class ActivityReferencingLifecycleListener extends Controller.LifecycleListener {
+        final List<Boolean> changeEndReferences = new ArrayList<>();
+        final List<Boolean> postCreateViewReferences = new ArrayList<>();
+        final List<Boolean> postAttachReferences = new ArrayList<>();
+        final List<Boolean> postDetachReferences = new ArrayList<>();
+        final List<Boolean> postDestroyViewReferences = new ArrayList<>();
+        final List<Boolean> postDestroyReferences = new ArrayList<>();
+
+        @Override
+        public void onChangeEnd(@NonNull Controller controller, @NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
+            changeEndReferences.add(controller.getActivity() != null);
+        }
+
+        @Override
+        public void postCreateView(@NonNull Controller controller, @NonNull View view) {
+            postCreateViewReferences.add(controller.getActivity() != null);
+        }
+
+        @Override
+        public void postAttach(@NonNull Controller controller, @NonNull View view) {
+            postAttachReferences.add(controller.getActivity() != null);
+        }
+
+        @Override
+        public void postDetach(@NonNull Controller controller, @NonNull View view) {
+            postDetachReferences.add(controller.getActivity() != null);
+        }
+
+        @Override
+        public void postDestroyView(@NonNull Controller controller) {
+            postDestroyViewReferences.add(controller.getActivity() != null);
+        }
+
+        @Override
+        public void postDestroy(@NonNull Controller controller) {
+            postDestroyReferences.add(controller.getActivity() != null);
+        }
+    }
+
+}

conductor/src/test/java/com/bluelinelabs/conductor/ControllerLifecycleCallbacksTests.java

@@ -1,16 +1,20 @@
 package com.bluelinelabs.conductor;
 
+import android.content.Context;
 import android.os.Bundle;
-import android.support.annotation.NonNull;
+import androidx.annotation.NonNull;
 import android.view.View;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.Controller.LifecycleListener;
+import com.bluelinelabs.conductor.Controller.RetainViewMode;
+import com.bluelinelabs.conductor.changehandler.SimpleSwapChangeHandler;
 import com.bluelinelabs.conductor.util.ActivityProxy;
 import com.bluelinelabs.conductor.util.CallState;
 import com.bluelinelabs.conductor.util.MockChangeHandler;
 import com.bluelinelabs.conductor.util.MockChangeHandler.ChangeHandlerListener;
 import com.bluelinelabs.conductor.util.TestController;
+import com.bluelinelabs.conductor.util.ViewUtils;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -19,11 +23,14 @@ import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
-public class ControllerLifecycleTests {
+public class ControllerLifecycleCallbacksTests {
 
     private Router router;
 
@@ -47,7 +54,7 @@ public class ControllerLifecycleTests {
     public void setup() {
         createActivityController(null, true);
 
-        currentCallState = new CallState();
+        currentCallState = new CallState(false);
     }
 
     @Test
@@ -55,7 +62,7 @@ public class ControllerLifecycleTests {
         TestController controller = new TestController();
         attachLifecycleListener(controller);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, controller);
         router.pushController(RouterTransaction.with(controller)
@@ -72,11 +79,11 @@ public class ControllerLifecycleTests {
     }
 
     @Test
-    public void testLifecycleWithActivityDestroy() {
+    public void testLifecycleWithActivityStop() {
         TestController controller = new TestController();
         attachLifecycleListener(controller);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, controller);
         router.pushController(RouterTransaction.with(controller)
@@ -89,7 +96,38 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, controller);
 
-        activityProxy.stop();
+        activityProxy.stop(false);
+
+        expectedCallState.detachCalls++;
+        assertCalls(expectedCallState, controller);
+
+        assertNotNull(controller.getView());
+        ViewUtils.reportAttached(controller.getView(), false);
+
+        expectedCallState.saveViewStateCalls++;
+        expectedCallState.destroyViewCalls++;
+        assertCalls(expectedCallState, controller);
+    }
+
+    @Test
+    public void testLifecycleWithActivityDestroy() {
+        TestController controller = new TestController();
+        attachLifecycleListener(controller);
+
+        CallState expectedCallState = new CallState(false);
+
+        assertCalls(expectedCallState, controller);
+        router.pushController(RouterTransaction.with(controller)
+                .pushChangeHandler(getPushHandler(expectedCallState, controller)));
+
+        assertCalls(expectedCallState, controller);
+
+        activityProxy.getActivity().isDestroying = true;
+        activityProxy.pause();
+
+        assertCalls(expectedCallState, controller);
+
+        activityProxy.stop(true);
 
         expectedCallState.saveViewStateCalls++;
         expectedCallState.detachCalls++;
@@ -98,6 +136,7 @@ public class ControllerLifecycleTests {
 
         activityProxy.destroy();
 
+        expectedCallState.contextUnavailableCalls++;
         expectedCallState.destroyCalls++;
         assertCalls(expectedCallState, controller);
     }
@@ -107,7 +146,7 @@ public class ControllerLifecycleTests {
         TestController controller = new TestController();
         attachLifecycleListener(controller);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, controller);
         router.pushController(RouterTransaction.with(controller)
@@ -128,17 +167,19 @@ public class ControllerLifecycleTests {
         activityProxy.pause();
         assertCalls(expectedCallState, controller);
 
-        activityProxy.stop();
+        activityProxy.stop(true);
         expectedCallState.detachCalls++;
         expectedCallState.destroyViewCalls++;
         assertCalls(expectedCallState, controller);
 
         activityProxy.destroy();
+        expectedCallState.contextUnavailableCalls++;
         assertCalls(expectedCallState, controller);
 
         createActivityController(bundle, false);
         controller = (TestController)router.getControllerWithTag("root");
 
+        expectedCallState.contextAvailableCalls++;
         expectedCallState.restoreInstanceStateCalls++;
         expectedCallState.restoreViewStateCalls++;
         expectedCallState.changeStartCalls++;
@@ -151,6 +192,7 @@ public class ControllerLifecycleTests {
         currentCallState.changeEndCalls = controller.currentCallState.changeEndCalls;
         currentCallState.createViewCalls = controller.currentCallState.createViewCalls;
         currentCallState.attachCalls = controller.currentCallState.attachCalls;
+        currentCallState.contextAvailableCalls = controller.currentCallState.contextAvailableCalls;
 
         assertCalls(expectedCallState, controller);
 
@@ -171,7 +213,7 @@ public class ControllerLifecycleTests {
         TestController controller = new TestController();
         attachLifecycleListener(controller);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, controller);
         router.pushController(RouterTransaction.with(controller)
@@ -189,12 +231,14 @@ public class ControllerLifecycleTests {
         assertCalls(expectedCallState, controller);
 
         activityProxy.resume();
+
+        assertCalls(expectedCallState, controller);
     }
 
     @Test
     public void testLifecycleCallOrder() {
         final TestController testController = new TestController();
-        final CallState callState = new CallState();
+        final CallState callState = new CallState(false);
 
         testController.addLifecycleListener(new LifecycleListener() {
             @Override
@@ -410,7 +454,7 @@ public class ControllerLifecycleTests {
         TestController child = new TestController();
         attachLifecycleListener(child);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, child);
 
@@ -437,7 +481,7 @@ public class ControllerLifecycleTests {
         TestController child = new TestController();
         attachLifecycleListener(child);
 
-        CallState expectedCallState = new CallState();
+        CallState expectedCallState = new CallState(false);
 
         assertCalls(expectedCallState, child);
 
@@ -453,15 +497,49 @@ public class ControllerLifecycleTests {
 
         expectedCallState.detachCalls++;
         expectedCallState.destroyViewCalls++;
+        expectedCallState.contextUnavailableCalls++;
         expectedCallState.destroyCalls++;
 
         assertCalls(expectedCallState, child);
     }
 
+    @Test
+    public void testChildLifecycleOrderingAfterUnexpectedAttach() {
+        Controller parent = new TestController();
+        parent.setRetainViewMode(RetainViewMode.RETAIN_DETACH);
+        router.pushController(RouterTransaction.with(parent)
+                .pushChangeHandler(MockChangeHandler.defaultHandler())
+                .popChangeHandler(MockChangeHandler.defaultHandler()));
+
+        TestController child = new TestController();
+        child.setRetainViewMode(RetainViewMode.RETAIN_DETACH);
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter
+                .setRoot(RouterTransaction.with(child)
+                        .pushChangeHandler(new SimpleSwapChangeHandler())
+                        .popChangeHandler(new SimpleSwapChangeHandler()));
+
+        assertTrue(parent.isAttached());
+        assertTrue(child.isAttached());
+
+        ViewUtils.reportAttached(parent.getView(), false, true);
+        assertFalse(parent.isAttached());
+        assertFalse(child.isAttached());
+
+        ViewUtils.reportAttached(child.getView(), true);
+        assertFalse(parent.isAttached());
+        assertFalse(child.isAttached());
+
+        ViewUtils.reportAttached(parent.getView(), true);
+        assertTrue(parent.isAttached());
+        assertTrue(child.isAttached());
+    }
+
     private MockChangeHandler getPushHandler(final CallState expectedCallState, final TestController controller) {
         return MockChangeHandler.listeningChangeHandler(new ChangeHandlerListener() {
             @Override
             public void willStartChange() {
+                expectedCallState.contextAvailableCalls++;
                 expectedCallState.changeStartCalls++;
                 expectedCallState.createViewCalls++;
                 assertCalls(expectedCallState, controller);
@@ -493,6 +571,7 @@ public class ControllerLifecycleTests {
             public void didAttachOrDetach() {
                 expectedCallState.destroyViewCalls++;
                 expectedCallState.detachCalls++;
+                expectedCallState.contextUnavailableCalls++;
                 expectedCallState.destroyCalls++;
                 assertCalls(expectedCallState, controller);
             }
@@ -522,6 +601,16 @@ public class ControllerLifecycleTests {
                 currentCallState.changeEndCalls++;
             }
 
+            @Override
+            public void postContextAvailable(@NonNull Controller controller, @NonNull Context context) {
+                currentCallState.contextAvailableCalls++;
+            }
+
+            @Override
+            public void postContextUnavailable(@NonNull Controller controller) {
+                currentCallState.contextUnavailableCalls++;
+            }
+
             @Override
             public void postCreateView(@NonNull Controller controller, @NonNull View view) {
                 currentCallState.createViewCalls++;

conductor/src/test/java/com/bluelinelabs/conductor/ControllerTests.java

@@ -21,6 +21,7 @@ import org.robolectric.annotation.Config;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
@@ -362,6 +363,48 @@ public class ControllerTests {
         assertNull(child2.getParentController());
     }
 
+    @Test
+    public void testRestoredChildRouterBackstack() {
+        TestController parent = new TestController();
+        router.pushController(RouterTransaction.with(parent));
+        ViewUtils.reportAttached(parent.getView(), true);
+
+        RouterTransaction childTransaction1 = RouterTransaction.with(new TestController());
+        RouterTransaction childTransaction2 = RouterTransaction.with(new TestController());
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_1));
+        childRouter.setPopsLastView(true);
+        childRouter.setRoot(childTransaction1);
+        childRouter.pushController(childTransaction2);
+
+        Bundle savedState = new Bundle();
+        childRouter.saveInstanceState(savedState);
+        parent.removeChildRouter(childRouter);
+
+        childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_1));
+        assertEquals(0, childRouter.getBackstackSize());
+
+        childRouter.restoreInstanceState(savedState);
+        childRouter.rebindIfNeeded();
+
+        assertEquals(2, childRouter.getBackstackSize());
+
+        RouterTransaction restoredChildTransaction1 = childRouter.getBackstack().get(0);
+        RouterTransaction restoredChildTransaction2 = childRouter.getBackstack().get(1);
+
+        assertEquals(childTransaction1.transactionIndex, restoredChildTransaction1.transactionIndex);
+        assertEquals(childTransaction1.controller.getInstanceId(), restoredChildTransaction1.controller.getInstanceId());
+        assertEquals(childTransaction2.transactionIndex, restoredChildTransaction2.transactionIndex);
+        assertEquals(childTransaction2.controller.getInstanceId(), restoredChildTransaction2.controller.getInstanceId());
+
+        assertTrue(parent.handleBack());
+        assertEquals(1, childRouter.getBackstackSize());
+        assertEquals(restoredChildTransaction1, childRouter.getBackstack().get(0));
+
+        assertTrue(parent.handleBack());
+        assertEquals(0, childRouter.getBackstackSize());
+    }
+
     private void assertCalls(CallState callState, TestController controller) {
         assertEquals("Expected call counts and controller call counts do not match.", callState, controller.currentCallState);
     }

conductor/src/test/java/com/bluelinelabs/conductor/ReattachCaseTests.java

@@ -6,6 +6,7 @@ import android.view.ViewGroup;
 import com.bluelinelabs.conductor.util.ActivityProxy;
 import com.bluelinelabs.conductor.util.MockChangeHandler;
 import com.bluelinelabs.conductor.util.TestController;
+import com.bluelinelabs.conductor.util.ViewUtils;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -232,6 +233,60 @@ public class ReattachCaseTests {
         assertFalse(childController.isAttached());
     }
 
+    // Attempt to test https://github.com/bluelinelabs/Conductor/issues/367
+    @Test
+    public void testViewIsAttachedAfterStartedActivityIsRecreated() {
+        Controller controller1 = new TestController();
+        Controller controller2 = new TestController();
+
+        router.setRoot(RouterTransaction.with(controller1));
+        assertTrue(controller1.isAttached());
+
+        // Lock screen
+        Bundle bundle = new Bundle();
+        activityProxy.pause().saveInstanceState(bundle).stop(false);
+
+        // Push a 2nd controller, which will rotate the screen once it unlocked
+        router.pushController(RouterTransaction.with(controller2));
+        assertTrue(controller2.isAttached());
+        assertTrue(controller2.getNeedsAttach());
+
+        // Unlock screen and rotate
+        activityProxy.start();
+        activityProxy.rotate();
+
+        assertTrue(controller2.isAttached());
+    }
+
+    @Test
+    public void testPopMiddleControllerAttaches() {
+        Controller controller1 = new TestController();
+        Controller controller2 = new TestController();
+        Controller controller3 = new TestController();
+
+        router.setRoot(RouterTransaction.with(controller1));
+        router.pushController(RouterTransaction.with(controller2));
+        router.pushController(RouterTransaction.with(controller3));
+        router.popController(controller2);
+
+        assertFalse(controller1.isAttached());
+        assertFalse(controller2.isAttached());
+        assertTrue(controller3.isAttached());
+
+        controller1 = new TestController();
+        controller2 = new TestController();
+        controller3 = new TestController();
+
+        router.setRoot(RouterTransaction.with(controller1));
+        router.pushController(RouterTransaction.with(controller2));
+        router.pushController(RouterTransaction.with(controller3).pushChangeHandler(MockChangeHandler.noRemoveViewOnPushHandler()));
+        router.popController(controller2);
+
+        assertTrue(controller1.isAttached());
+        assertFalse(controller2.isAttached());
+        assertTrue(controller3.isAttached());
+    }
+
     private void sleepWakeDevice() {
         activityProxy.saveInstanceState(new Bundle()).pause();
         activityProxy.resume();

conductor/src/test/java/com/bluelinelabs/conductor/RouterChangeHandlerTests.java

@@ -3,7 +3,6 @@ package com.bluelinelabs.conductor;
 import android.view.View;
 
 import com.bluelinelabs.conductor.util.ActivityProxy;
-import com.bluelinelabs.conductor.util.ListUtils;
 import com.bluelinelabs.conductor.util.MockChangeHandler;
 import com.bluelinelabs.conductor.util.TestController;
 
@@ -13,6 +12,7 @@ import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
+import java.util.Arrays;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -142,7 +142,7 @@ public class RouterChangeHandlerTests {
         TestController newController2 = new TestController();
         MockChangeHandler setBackstackHandler = MockChangeHandler.taggedHandler("setBackstackHandler", true);
 
-        List<RouterTransaction> newBackstack = ListUtils.listOf(
+        List<RouterTransaction> newBackstack = Arrays.asList(
                 RouterTransaction.with(newController1),
                 RouterTransaction.with(newController2)
         );
@@ -193,10 +193,10 @@ public class RouterChangeHandlerTests {
         TestController newController1 = new TestController();
         TestController newController2 = new TestController();
         MockChangeHandler setBackstackHandler = MockChangeHandler.taggedHandler("setBackstackHandler", true);
-
-        List<RouterTransaction> newBackstack = ListUtils.listOf(
+        MockChangeHandler pushController2Handler = MockChangeHandler.noRemoveViewOnPushHandler("pushController2");
+        List<RouterTransaction> newBackstack = Arrays.asList(
                 RouterTransaction.with(newController1),
-                RouterTransaction.with(newController2).pushChangeHandler(MockChangeHandler.noRemoveViewOnPushHandler())
+                RouterTransaction.with(newController2).pushChangeHandler(pushController2Handler)
         );
 
         router.setBackstack(newBackstack, setBackstackHandler);
@@ -226,14 +226,129 @@ public class RouterChangeHandlerTests {
         assertEquals(newController2.getView(), newController1.changeHandlerHistory.latestToView());
         assertEquals(initialView1, newController1.changeHandlerHistory.fromViewAt(0));
         assertEquals(newController1.getView(), newController1.changeHandlerHistory.latestFromView());
-        assertEquals(setBackstackHandler.tag, newController1.changeHandlerHistory.latestChangeHandler().tag);
+        assertEquals(setBackstackHandler.tag, newController1.changeHandlerHistory.changeHandlerAt(0).tag);
+        assertEquals(pushController2Handler.tag, newController1.changeHandlerHistory.latestChangeHandler().tag);
         assertTrue(newController1.changeHandlerHistory.latestIsPush());
 
         assertNotNull(newController2.changeHandlerHistory.latestToView());
         assertEquals(newController2.getView(), newController2.changeHandlerHistory.latestToView());
         assertEquals(newController1.getView(), newController2.changeHandlerHistory.latestFromView());
-        assertEquals(setBackstackHandler.tag, newController2.changeHandlerHistory.latestChangeHandler().tag);
+        assertEquals(pushController2Handler.tag, newController2.changeHandlerHistory.latestChangeHandler().tag);
         assertTrue(newController2.changeHandlerHistory.latestIsPush());
     }
 
+    @Test
+    public void testSetBackstackForPushHandlers() {
+        TestController initialController = new TestController();
+        MockChangeHandler initialPushHandler = MockChangeHandler.taggedHandler("initialPush1", true);
+        MockChangeHandler initialPopHandler = MockChangeHandler.taggedHandler("initialPop1", true);
+        RouterTransaction initialTransaction = RouterTransaction.with(initialController).pushChangeHandler(initialPushHandler).popChangeHandler(initialPopHandler);
+        router.setRoot(initialTransaction);
+        View initialView = initialController.getView();
+
+        TestController newController = new TestController();
+        MockChangeHandler setBackstackHandler = MockChangeHandler.taggedHandler("setBackstackHandler", true);
+
+        List<RouterTransaction> newBackstack = Arrays.asList(
+                initialTransaction,
+                RouterTransaction.with(newController)
+        );
+
+        router.setBackstack(newBackstack, setBackstackHandler);
+
+        assertTrue(initialController.changeHandlerHistory.isValidHistory);
+        assertTrue(newController.changeHandlerHistory.isValidHistory);
+
+        assertEquals(2, initialController.changeHandlerHistory.size());
+        assertEquals(1, newController.changeHandlerHistory.size());
+
+        assertNotNull(initialController.changeHandlerHistory.latestToView());
+        assertEquals(newController.getView(), initialController.changeHandlerHistory.latestToView());
+        assertEquals(initialView, initialController.changeHandlerHistory.latestFromView());
+        assertEquals(setBackstackHandler.tag, initialController.changeHandlerHistory.latestChangeHandler().tag);
+        assertTrue(initialController.changeHandlerHistory.latestIsPush());
+        assertTrue(newController.changeHandlerHistory.latestIsPush());
+    }
+
+    @Test
+    public void testSetBackstackForInvertHandlersWithRemovesView() {
+        TestController initialController1 = new TestController();
+        MockChangeHandler initialPushHandler1 = MockChangeHandler.taggedHandler("initialPush1", true);
+        MockChangeHandler initialPopHandler1 = MockChangeHandler.taggedHandler("initialPop1", true);
+        RouterTransaction initialTransaction1 = RouterTransaction.with(initialController1).pushChangeHandler(initialPushHandler1).popChangeHandler(initialPopHandler1);
+        router.setRoot(initialTransaction1);
+        TestController initialController2 = new TestController();
+        MockChangeHandler initialPushHandler2 = MockChangeHandler.taggedHandler("initialPush2", true);
+        MockChangeHandler initialPopHandler2 = MockChangeHandler.taggedHandler("initialPop2", true);
+        RouterTransaction initialTransaction2 = RouterTransaction.with(initialController2).pushChangeHandler(initialPushHandler2).popChangeHandler(initialPopHandler2);
+        router.pushController(initialTransaction2);
+
+        View initialView2 = initialController2.getView();
+
+        MockChangeHandler setBackstackHandler = MockChangeHandler.taggedHandler("setBackstackHandler", true);
+        List<RouterTransaction> newBackstack = Arrays.asList(
+                initialTransaction2,
+                initialTransaction1
+        );
+
+        router.setBackstack(newBackstack, setBackstackHandler);
+
+        assertTrue(initialController1.changeHandlerHistory.isValidHistory);
+        assertTrue(initialController2.changeHandlerHistory.isValidHistory);
+
+        assertEquals(3, initialController1.changeHandlerHistory.size());
+        assertEquals(2, initialController2.changeHandlerHistory.size());
+
+        assertNotNull(initialController1.changeHandlerHistory.latestToView());
+        assertEquals(initialView2, initialController1.changeHandlerHistory.latestFromView());
+        assertEquals(setBackstackHandler.tag, initialController1.changeHandlerHistory.latestChangeHandler().tag);
+        assertFalse(initialController1.changeHandlerHistory.latestIsPush());
+
+        assertNotNull(initialController2.changeHandlerHistory.latestToView());
+        assertEquals(initialView2, initialController2.changeHandlerHistory.latestFromView());
+        assertEquals(setBackstackHandler.tag, initialController2.changeHandlerHistory.latestChangeHandler().tag);
+        assertFalse(initialController2.changeHandlerHistory.latestIsPush());
+    }
+
+    @Test
+    public void testSetBackstackForInvertHandlersWithoutRemovesView() {
+        TestController initialController1 = new TestController();
+        MockChangeHandler initialPushHandler1 = MockChangeHandler.taggedHandler("initialPush1", true);
+        MockChangeHandler initialPopHandler1 = MockChangeHandler.taggedHandler("initialPop1", true);
+        RouterTransaction initialTransaction1 = RouterTransaction.with(initialController1).pushChangeHandler(initialPushHandler1).popChangeHandler(initialPopHandler1);
+        router.setRoot(initialTransaction1);
+        TestController initialController2 = new TestController();
+        MockChangeHandler initialPushHandler2 = MockChangeHandler.taggedHandler("initialPush2", false);
+        MockChangeHandler initialPopHandler2 = MockChangeHandler.taggedHandler("initialPop2", false);
+        RouterTransaction initialTransaction2 = RouterTransaction.with(initialController2).pushChangeHandler(initialPushHandler2).popChangeHandler(initialPopHandler2);
+        router.pushController(initialTransaction2);
+
+        View initialView1 = initialController1.getView();
+        View initialView2 = initialController2.getView();
+
+        MockChangeHandler setBackstackHandler = MockChangeHandler.taggedHandler("setBackstackHandler", true);
+        List<RouterTransaction> newBackstack = Arrays.asList(
+                initialTransaction2,
+                initialTransaction1
+        );
+
+        router.setBackstack(newBackstack, setBackstackHandler);
+
+        assertTrue(initialController1.changeHandlerHistory.isValidHistory);
+        assertTrue(initialController2.changeHandlerHistory.isValidHistory);
+
+        assertEquals(2, initialController1.changeHandlerHistory.size());
+        assertEquals(2, initialController2.changeHandlerHistory.size());
+
+        assertNotNull(initialController1.changeHandlerHistory.latestToView());
+        assertEquals(initialView1, initialController1.changeHandlerHistory.latestFromView());
+        assertEquals(initialPushHandler2.tag, initialController1.changeHandlerHistory.latestChangeHandler().tag);
+        assertTrue(initialController1.changeHandlerHistory.latestIsPush());
+
+        assertNull(initialController2.changeHandlerHistory.latestToView());
+        assertEquals(initialView2, initialController2.changeHandlerHistory.latestFromView());
+        assertEquals(setBackstackHandler.tag, initialController2.changeHandlerHistory.latestChangeHandler().tag);
+        assertFalse(initialController2.changeHandlerHistory.latestIsPush());
+    }
+
 }

conductor/src/test/java/com/bluelinelabs/conductor/RouterTests.java

@@ -1,7 +1,13 @@
 package com.bluelinelabs.conductor;
 
+import androidx.annotation.NonNull;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.bluelinelabs.conductor.Controller.LifecycleListener;
+import com.bluelinelabs.conductor.changehandler.FadeChangeHandler;
+import com.bluelinelabs.conductor.changehandler.HorizontalChangeHandler;
 import com.bluelinelabs.conductor.util.ActivityProxy;
-import com.bluelinelabs.conductor.util.ListUtils;
 import com.bluelinelabs.conductor.util.MockChangeHandler;
 import com.bluelinelabs.conductor.util.TestController;
 
@@ -11,6 +17,7 @@ import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
+import java.util.Arrays;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -121,6 +128,31 @@ public class RouterTests {
         assertNull(router.getControllerWithTag(controller2Tag));
     }
 
+    @Test
+    public void testPopControllerConcurrentModificationException() {
+        int step = 1;
+        for (int i = 0; i < 10; i++, step++) {
+            router.pushController(RouterTransaction.with(new TestController()).tag("1"));
+            router.pushController(RouterTransaction.with(new TestController()).tag("2"));
+            router.pushController(RouterTransaction.with(new TestController()).tag("3"));
+
+            String tag;
+            if (step == 1) {
+                tag = "1";
+            } else if (step == 2) {
+                tag = "2";
+            } else {
+                tag = "3";
+                step = 0;
+            }
+            Controller controller = router.getControllerWithTag(tag);
+            if (controller != null) {
+                router.popController(controller);
+            }
+            router.popToRoot();
+        }
+    }
+
     @Test
     public void testPopToTag() {
         String controller1Tag = "controller1";
@@ -187,7 +219,7 @@ public class RouterTests {
         RouterTransaction middleTransaction = RouterTransaction.with(new TestController());
         RouterTransaction topTransaction = RouterTransaction.with(new TestController());
 
-        List<RouterTransaction> backstack = ListUtils.listOf(rootTransaction, middleTransaction, topTransaction);
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, middleTransaction, topTransaction);
         router.setBackstack(backstack, null);
 
         assertEquals(3, router.getBackstackSize());
@@ -208,7 +240,7 @@ public class RouterTests {
         RouterTransaction middleTransaction = RouterTransaction.with(new TestController());
         RouterTransaction topTransaction = RouterTransaction.with(new TestController());
 
-        List<RouterTransaction> backstack = ListUtils.listOf(rootTransaction, middleTransaction, topTransaction);
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, middleTransaction, topTransaction);
         router.setBackstack(backstack, null);
 
         assertEquals(3, router.getBackstackSize());
@@ -239,7 +271,7 @@ public class RouterTests {
         RouterTransaction middleTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(MockChangeHandler.noRemoveViewOnPushHandler());
         RouterTransaction topTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(MockChangeHandler.noRemoveViewOnPushHandler());
 
-        List<RouterTransaction> backstack = ListUtils.listOf(rootTransaction, middleTransaction, topTransaction);
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, middleTransaction, topTransaction);
         router.setBackstack(backstack, null);
 
         assertEquals(3, router.getBackstackSize());
@@ -256,12 +288,54 @@ public class RouterTests {
         assertTrue(topTransaction.controller.isAttached());
     }
 
+    @Test
+    public void testPopToRoot() {
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction transaction1 = RouterTransaction.with(new TestController());
+        RouterTransaction transaction2 = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, transaction1, transaction2);
+        router.setBackstack(backstack, null);
+
+        assertEquals(3, router.getBackstackSize());
+
+        router.popToRoot();
+
+        assertEquals(1, router.getBackstackSize());
+        assertEquals(rootTransaction, router.getBackstack().get(0));
+
+        assertTrue(rootTransaction.controller.isAttached());
+        assertFalse(transaction1.controller.isAttached());
+        assertFalse(transaction2.controller.isAttached());
+    }
+
+    @Test
+    public void testPopToRootWithNoRemoveViewOnPush() {
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new HorizontalChangeHandler(false));
+        RouterTransaction transaction1 = RouterTransaction.with(new TestController()).pushChangeHandler(new HorizontalChangeHandler(false));
+        RouterTransaction transaction2 = RouterTransaction.with(new TestController()).pushChangeHandler(new HorizontalChangeHandler(false));
+
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, transaction1, transaction2);
+        router.setBackstack(backstack, null);
+
+        assertEquals(3, router.getBackstackSize());
+
+        router.popToRoot();
+
+        assertEquals(1, router.getBackstackSize());
+        assertEquals(rootTransaction, router.getBackstack().get(0));
+
+        assertTrue(rootTransaction.controller.isAttached());
+        assertFalse(transaction1.controller.isAttached());
+        assertFalse(transaction2.controller.isAttached());
+    }
+
     @Test
     public void testReplaceTopController() {
         RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
         RouterTransaction topTransaction = RouterTransaction.with(new TestController());
 
-        List<RouterTransaction> backstack = ListUtils.listOf(rootTransaction, topTransaction);
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, topTransaction);
         router.setBackstack(backstack, null);
 
         assertEquals(2, router.getBackstackSize());
@@ -285,7 +359,7 @@ public class RouterTests {
         RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
         RouterTransaction topTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(MockChangeHandler.noRemoveViewOnPushHandler());
 
-        List<RouterTransaction> backstack = ListUtils.listOf(rootTransaction, topTransaction);
+        List<RouterTransaction> backstack = Arrays.asList(rootTransaction, topTransaction);
         router.setBackstack(backstack, null);
 
         assertEquals(2, router.getBackstackSize());
@@ -312,4 +386,110 @@ public class RouterTests {
         assertTrue(newTopTransaction.controller.isAttached());
     }
 
+    @Test
+    public void testRearrangeTransactionBackstack() {
+        RouterTransaction transaction1 = RouterTransaction.with(new TestController());
+        RouterTransaction transaction2 = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = Arrays.asList(transaction1, transaction2);
+        router.setBackstack(backstack, null);
+
+        assertEquals(1, transaction1.transactionIndex);
+        assertEquals(2, transaction2.transactionIndex);
+
+        backstack = Arrays.asList(transaction2, transaction1);
+        router.setBackstack(backstack, null);
+
+        assertEquals(1, transaction2.transactionIndex);
+        assertEquals(2, transaction1.transactionIndex);
+
+        router.handleBack();
+
+        assertEquals(1, router.getBackstackSize());
+        assertEquals(transaction2, router.getBackstack().get(0));
+
+        router.handleBack();
+        assertEquals(0, router.getBackstackSize());
+    }
+
+    @Test
+    public void testChildRouterRearrangeTransactionBackstack() {
+        Controller parent = new TestController();
+        router.setRoot(RouterTransaction.with(parent));
+
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_1));
+
+        RouterTransaction transaction1 = RouterTransaction.with(new TestController());
+        RouterTransaction transaction2 = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = Arrays.asList(transaction1, transaction2);
+        childRouter.setBackstack(backstack, null);
+
+        assertEquals(2, transaction1.transactionIndex);
+        assertEquals(3, transaction2.transactionIndex);
+
+        backstack = Arrays.asList(transaction2, transaction1);
+        childRouter.setBackstack(backstack, null);
+
+        assertEquals(2, transaction2.transactionIndex);
+        assertEquals(3, transaction1.transactionIndex);
+
+        childRouter.handleBack();
+
+        assertEquals(1, childRouter.getBackstackSize());
+        assertEquals(transaction2, childRouter.getBackstack().get(0));
+
+        childRouter.handleBack();
+        assertEquals(0, childRouter.getBackstackSize());
+    }
+
+    @Test
+    public void testRemovesAllViewsOnDestroy() {
+        Controller controller1 = new TestController();
+        Controller controller2 = new TestController();
+
+        router.setRoot(RouterTransaction.with(controller1));
+        router.pushController(RouterTransaction.with(controller2)
+                .pushChangeHandler(new FadeChangeHandler(false)));
+
+        assertEquals(2, router.container.getChildCount());
+
+        router.destroy(true);
+
+        assertEquals(0, router.container.getChildCount());
+    }
+
+    @Test
+    public void testIsBeingDestroyed() {
+        final LifecycleListener lifecycleListener = new LifecycleListener() {
+            @Override
+            public void preDestroyView(@NonNull Controller controller, @NonNull View view) {
+                assertTrue(controller.isBeingDestroyed());
+            }
+        };
+
+        Controller controller1 = new TestController();
+        Controller controller2 = new TestController();
+        controller2.addLifecycleListener(lifecycleListener);
+
+        router.setRoot(RouterTransaction.with(controller1));
+        router.pushController(RouterTransaction.with(controller2));
+        assertFalse(controller1.isBeingDestroyed());
+        assertFalse(controller2.isBeingDestroyed());
+
+        router.popCurrentController();
+        assertFalse(controller1.isBeingDestroyed());
+        assertTrue(controller2.isBeingDestroyed());
+
+        Controller controller3 = new TestController();
+        controller3.addLifecycleListener(lifecycleListener);
+        router.pushController(RouterTransaction.with(controller3));
+        assertFalse(controller1.isBeingDestroyed());
+        assertFalse(controller3.isBeingDestroyed());
+
+        router.popToRoot();
+        assertFalse(controller1.isBeingDestroyed());
+        assertTrue(controller3.isBeingDestroyed());
+    }
+
 }

conductor/src/test/java/com/bluelinelabs/conductor/ViewAttachHandlerTests.java

@@ -40,55 +40,107 @@ public class ViewAttachHandlerTests {
 
         assertEquals(0, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(2, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStopped();
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, false);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, true);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStarted();
+        assertEquals(3, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
     }
 
     @Test
     public void testSimpleViewGroupAttachDetach() {
-        View view = new LinearLayout(activity);
+        View view = new View(activity);
         viewAttachHandler.listenForAttach(view);
 
         assertEquals(0, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true);
         assertEquals(2, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStopped();
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, false);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, true);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStarted();
+        assertEquals(3, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
     }
 
     @Test
@@ -100,50 +152,85 @@ public class ViewAttachHandlerTests {
 
         assertEquals(0, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true, false);
         assertEquals(0, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(child, true, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true, false);
         ViewUtils.reportAttached(child, true, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(0, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, false, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(view, true, false);
         assertEquals(1, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
 
         ViewUtils.reportAttached(child, true, false);
         assertEquals(2, viewAttachListener.attaches);
         assertEquals(1, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStopped();
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(0, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, false, false);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        ViewUtils.reportAttached(view, true, false);
+        ViewUtils.reportAttached(child, true, false);
+        assertEquals(2, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
+
+        viewAttachHandler.onActivityStarted();
+        assertEquals(3, viewAttachListener.attaches);
+        assertEquals(2, viewAttachListener.detaches);
+        assertEquals(1, viewAttachListener.detachAfterStops);
     }
 
     private static class CountingViewAttachListener implements ViewAttachListener {
         int attaches;
         int detaches;
+        int detachAfterStops;
 
         @Override
-        public void onAttached(View view) {
+        public void onAttached() {
             attaches++;
         }
 
         @Override
-        public void onDetached(View view) {
+        public void onDetached(boolean fromActivityStop) {
             detaches++;
         }
+
+        @Override
+        public void onViewDetachAfterStop() {
+            detachAfterStops++;
+        }
     }
 
 }

conductor/src/test/java/com/bluelinelabs/conductor/ViewLeakTests.java

@@ -0,0 +1,132 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import android.view.View;
+import android.view.ViewGroup;
+
+import com.bluelinelabs.conductor.util.ActivityProxy;
+import com.bluelinelabs.conductor.util.TestController;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class ViewLeakTests {
+
+    private ActivityProxy activityProxy;
+    private Router router;
+
+    public void createActivityController(Bundle savedInstanceState) {
+        activityProxy = new ActivityProxy().create(savedInstanceState).start().resume();
+        router = Conductor.attachRouter(activityProxy.getActivity(), activityProxy.getView(), savedInstanceState);
+        if (!router.hasRootController()) {
+            router.setRoot(RouterTransaction.with(new TestController()));
+        }
+    }
+
+    @Before
+    public void setup() {
+        createActivityController(null);
+    }
+
+    @Test
+    public void testPop() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller));
+
+        assertNotNull(controller.getView());
+
+        router.popCurrentController();
+
+        assertNull(controller.getView());
+    }
+
+    @Test
+    public void testPopWhenPushNeverAdded() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller).pushChangeHandler(new NeverAddChangeHandler()));
+
+        assertNotNull(controller.getView());
+
+        router.popCurrentController();
+
+        assertNull(controller.getView());
+    }
+
+    @Test
+    public void testPopWhenPushNeverCompleted() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller).pushChangeHandler(new NeverCompleteChangeHandler()));
+
+        assertNotNull(controller.getView());
+
+        router.popCurrentController();
+
+        assertNull(controller.getView());
+    }
+
+    @Test
+    public void testActivityStop() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller));
+
+        assertNotNull(controller.getView());
+
+        activityProxy.stop(true);
+
+        assertNull(controller.getView());
+    }
+
+    @Test
+    public void testActivityStopWhenPushNeverCompleted() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller).pushChangeHandler(new NeverCompleteChangeHandler()));
+
+        assertNotNull(controller.getView());
+
+        activityProxy.stop(true);
+
+        assertNull(controller.getView());
+    }
+
+    @Test
+    public void testActivityDestroyWhenPushNeverAdded() {
+        Controller controller = new TestController();
+        router.pushController(RouterTransaction.with(controller).pushChangeHandler(new NeverAddChangeHandler()));
+
+        assertNotNull(controller.getView());
+
+        activityProxy.stop(true).destroy();
+
+        assertNull(controller.getView());
+    }
+
+    public static class NeverAddChangeHandler extends ControllerChangeHandler {
+        @Override
+        public void performChange(@NonNull final ViewGroup container, @Nullable View from, @Nullable final View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+            if (from != null) {
+                container.removeView(from);
+            }
+        }
+    }
+
+    public static class NeverCompleteChangeHandler extends ControllerChangeHandler {
+        @Override
+        public void performChange(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+            if (from != null) {
+                container.removeView(from);
+            }
+            container.addView(to);
+        }
+    }
+
+}

conductor/src/test/java/com/bluelinelabs/conductor/util/ActivityProxy.java

@@ -1,10 +1,10 @@
 package com.bluelinelabs.conductor.util;
 
 import android.os.Bundle;
-import android.support.annotation.IdRes;
+import androidx.annotation.IdRes;
 
 import org.robolectric.Robolectric;
-import org.robolectric.util.ActivityController;
+import org.robolectric.android.controller.ActivityController;
 
 public class ActivityProxy {
 
@@ -45,14 +45,19 @@ public class ActivityProxy {
         return this;
     }
 
-    public ActivityProxy stop() {
+    public ActivityProxy stop(boolean detachView) {
         activityController.stop();
-        view.setAttached(false);
+
+        if (detachView) {
+            view.setAttached(false);
+        }
+
         return this;
     }
 
     public ActivityProxy destroy() {
         activityController.destroy();
+        view.setAttached(false);
         return this;
     }
 

conductor/src/test/java/com/bluelinelabs/conductor/util/CallState.java

@@ -19,10 +19,8 @@ public class CallState implements Parcelable {
     public int onActivityResultCalls;
     public int onRequestPermissionsResultCalls;
     public int createOptionsMenuCalls;
-
-    public CallState() {
-        this(false);
-    }
+    public int contextAvailableCalls;
+    public int contextUnavailableCalls;
 
     public CallState(boolean setupForAddedController) {
         if (setupForAddedController) {
@@ -30,6 +28,7 @@ public class CallState implements Parcelable {
             changeEndCalls++;
             createViewCalls++;
             attachCalls++;
+            contextAvailableCalls++;
         }
     }
 
@@ -42,8 +41,14 @@ public class CallState implements Parcelable {
             return false;
         }
 
-        CallState callState = (CallState)o;
+        CallState callState = (CallState) o;
 
+        if (contextAvailableCalls != callState.contextAvailableCalls) {
+            return false;
+        }
+        if (contextUnavailableCalls != callState.contextUnavailableCalls) {
+            return false;
+        }
         if (changeStartCalls != callState.changeStartCalls) {
             return false;
         }
@@ -102,6 +107,8 @@ public class CallState implements Parcelable {
         result = 31 * result + onActivityResultCalls;
         result = 31 * result + onRequestPermissionsResultCalls;
         result = 31 * result + createOptionsMenuCalls;
+        result = 31 * result + contextAvailableCalls;
+        result = 31 * result + contextUnavailableCalls;
         return result;
     }
 
@@ -122,6 +129,8 @@ public class CallState implements Parcelable {
                 "\n    onActivityResultCalls=" + onActivityResultCalls +
                 "\n    onRequestPermissionsResultCalls=" + onRequestPermissionsResultCalls +
                 "\n    createOptionsMenuCalls=" + createOptionsMenuCalls +
+                "\n    contextAvailableCalls=" + contextAvailableCalls +
+                "\n    contextUnavailableCalls=" + contextUnavailableCalls +
                 "}\n";
     }
 
@@ -144,11 +153,13 @@ public class CallState implements Parcelable {
         out.writeInt(onActivityResultCalls);
         out.writeInt(onRequestPermissionsResultCalls);
         out.writeInt(createOptionsMenuCalls);
+        out.writeInt(contextAvailableCalls);
+        out.writeInt(contextUnavailableCalls);
     }
 
-    public static final Parcelable.Creator<CallState> CREATOR  = new Parcelable.Creator<CallState>() {
+    public static final Parcelable.Creator<CallState> CREATOR = new Parcelable.Creator<CallState>() {
         public CallState createFromParcel(Parcel in) {
-            CallState state = new CallState();
+            CallState state = new CallState(false);
 
             state.changeStartCalls = in.readInt();
             state.changeEndCalls = in.readInt();
@@ -164,6 +175,8 @@ public class CallState implements Parcelable {
             state.onActivityResultCalls = in.readInt();
             state.onRequestPermissionsResultCalls = in.readInt();
             state.createOptionsMenuCalls = in.readInt();
+            state.contextAvailableCalls = in.readInt();
+            state.contextUnavailableCalls = in.readInt();
 
             return state;
         }
@@ -172,4 +185,4 @@ public class CallState implements Parcelable {
             return new CallState[size];
         }
     };
-}
+}

conductor/src/test/java/com/bluelinelabs/conductor/util/ListUtils.java

@@ -1,16 +0,0 @@
-package com.bluelinelabs.conductor.util;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class ListUtils {
-
-    public static <T> List<T> listOf(T... elements) {
-        List<T> list = new ArrayList<>();
-        for (T element : elements) {
-            list.add(element);
-        }
-        return list;
-    }
-
-}

conductor/src/test/java/com/bluelinelabs/conductor/util/MockChangeHandler.java

@@ -1,8 +1,8 @@
 package com.bluelinelabs.conductor.util;
 
 import android.os.Bundle;
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -34,6 +34,10 @@ public class MockChangeHandler extends ControllerChangeHandler {
         return new MockChangeHandler(false, null, null);
     }
 
+    public static MockChangeHandler noRemoveViewOnPushHandler(String tag) {
+        return new MockChangeHandler(false, tag, null);
+    }
+
     public static MockChangeHandler listeningChangeHandler(@NonNull ChangeHandlerListener listener) {
         return new MockChangeHandler(true, null, listener);
     }
@@ -48,6 +52,7 @@ public class MockChangeHandler extends ControllerChangeHandler {
 
     private MockChangeHandler(boolean removesFromViewOnPush, String tag, ChangeHandlerListener listener) {
         this.removesFromViewOnPush = removesFromViewOnPush;
+        this.tag = tag;
 
         if (listener == null) {
             this.listener = new ChangeHandlerListener() { };

conductor/src/test/java/com/bluelinelabs/conductor/util/TestController.java

@@ -1,9 +1,10 @@
 package com.bluelinelabs.conductor.util;
 
+import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
-import android.support.annotation.IdRes;
-import android.support.annotation.NonNull;
+import androidx.annotation.IdRes;
+import androidx.annotation.NonNull;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -23,7 +24,7 @@ public class TestController extends Controller {
 
     private static final String KEY_CALL_STATE = "TestController.currentCallState";
 
-    public CallState currentCallState = new CallState();
+    public CallState currentCallState = new CallState(false);
     public ChangeHandlerHistory changeHandlerHistory = new ChangeHandlerHistory();
 
     @NonNull
@@ -33,11 +34,11 @@ public class TestController extends Controller {
         FrameLayout view = new AttachFakingFrameLayout(inflater.getContext());
         view.setId(VIEW_ID);
 
-        FrameLayout childContainer1 = new FrameLayout(inflater.getContext());
+        FrameLayout childContainer1 = new AttachFakingFrameLayout(inflater.getContext());
         childContainer1.setId(CHILD_VIEW_ID_1);
         view.addView(childContainer1);
 
-        FrameLayout childContainer2 = new FrameLayout(inflater.getContext());
+        FrameLayout childContainer2 = new AttachFakingFrameLayout(inflater.getContext());
         childContainer2.setId(CHILD_VIEW_ID_2);
         view.addView(childContainer2);
 
@@ -63,6 +64,18 @@ public class TestController extends Controller {
         }
     }
 
+    @Override
+    protected void onContextAvailable(@NonNull Context context) {
+        super.onContextAvailable(context);
+        currentCallState.contextAvailableCalls++;
+    }
+
+    @Override
+    protected void onContextUnavailable() {
+        super.onContextUnavailable();
+        currentCallState.contextUnavailableCalls++;
+    }
+
     @Override
     protected void onAttach(@NonNull View view) {
         super.onAttach(view);

conductor/src/test/java/com/bluelinelabs/conductor/util/ViewUtils.java

@@ -16,7 +16,7 @@ public class ViewUtils {
 
     public static void reportAttached(View view, boolean attached, boolean propogateToChildren) {
         if (view instanceof AttachFakingFrameLayout) {
-            ((AttachFakingFrameLayout)view).setAttached(attached, false);
+            ((AttachFakingFrameLayout) view).setAttached(attached, false);
         }
 
         List<OnAttachStateChangeListener> listeners = getAttachStateListeners(view);
@@ -44,7 +44,7 @@ public class ViewUtils {
         }
 
         if (propogateToChildren && view instanceof ViewGroup) {
-            ViewGroup viewGroup = (ViewGroup)view;
+            ViewGroup viewGroup = (ViewGroup) view;
             int childCount = viewGroup.getChildCount();
             for (int i = 0; i < childCount; i++) {
                 reportAttached(viewGroup.getChildAt(i), attached, true);

demo/build.gradle

@@ -1,35 +1,20 @@
-buildscript {
-    repositories {
-        jcenter()
-    }
-    dependencies {
-        classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'
-    }
-}
-
 apply plugin: 'com.android.application'
-apply plugin: 'com.neenbedankt.android-apt'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion '24.0.3'
-
-    lintOptions {
-        abortOnError true
-        ignore 'UnusedResources'
-    }
+    compileSdkVersion rootProject.ext.compileSdkVersion
 
     compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_7
-        targetCompatibility JavaVersion.VERSION_1_7
+        sourceCompatibility 1.8
+        targetCompatibility 1.8
     }
 
     defaultConfig {
         applicationId "com.bluelinelabs.conductor.demo"
-        minSdkVersion 16
-        targetSdkVersion 25
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
         versionCode 1
         versionName "1.0.0"
+        vectorDrawables.useSupportLibrary true
     }
 
     buildTypes {
@@ -45,18 +30,24 @@ android {
 }
 
 dependencies {
-    compile rootProject.ext.supportV4
-    compile rootProject.ext.supportDesign
+    implementation rootProject.ext.androidxAppCompat
+    implementation rootProject.ext.material
 
-    apt rootProject.ext.butterknifeCompiler
-    compile rootProject.ext.butterknife
-    compile rootProject.ext.picasso
+    implementation rootProject.ext.archComponentsLiveDataCore // Fix duplicate classes
 
-    compile project(':conductor-support')
-    compile project(':conductor-rxlifecycle')
-    compile project(':conductor-rxlifecycle2')
+    annotationProcessor rootProject.ext.butterknifeCompiler
+    implementation rootProject.ext.butterknife
+    implementation rootProject.ext.picasso
 
-    debugCompile rootProject.ext.leakCanary
-    releaseCompile rootProject.ext.leakCanaryNoOp
-    testCompile rootProject.ext.leakCanaryNoOp
+    implementation project(':conductor')
+    implementation project(':conductor-modules:viewpager')
+    implementation project(':conductor-modules:rxlifecycle')
+    implementation project(':conductor-modules:rxlifecycle2')
+    implementation project(':conductor-modules:autodispose')
+    implementation project(':conductor-modules:arch-components-lifecycle')
+    implementation project(':conductor-modules:androidx-transition')
+
+    debugImplementation rootProject.ext.leakCanary
+    releaseImplementation rootProject.ext.leakCanaryNoOp
+    testImplementation rootProject.ext.leakCanaryNoOp
 }