Version bump

* Navigation Demos: "GO UP" is hidden in "Controller #0" - this closes #158

* Multiple Child Routers: "GO UP" is hidden for all - #158

.travis.yml

@@ -14,14 +14,10 @@ jdk:
   - oraclejdk8
 
 branches:
-  only
-    - v2
+  only:
     - develop
     - master
 
-before_install:
-  - chmod +x .buildscript/deploy_snapshot.sh
-
 after_success:
   - .buildscript/deploy_snapshot.sh
 

README.md

@@ -20,22 +20,33 @@ Conductor is architecture-agnostic and does not try to force any design decision
 ## Installation
 
 ```gradle
-compile 'com.bluelinelabs:conductor:2.0.0'
+compile 'com.bluelinelabs:conductor:2.0.4'
 
 // If you want the components that go along with
 // Android's support libraries (currently just a PagerAdapter):
-compile 'com.bluelinelabs:conductor-support:2.0.0'
+compile 'com.bluelinelabs:conductor-support:2.0.4'
 
 // If you want RxJava/RxAndroid lifecycle support:
-compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.0'
+compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.4'
 ```
 
 SNAPSHOT:
 
 ```gradle
-compile 'com.bluelinelabs:conductor:2.0.1-SNAPSHOT'
-compile 'com.bluelinelabs:conductor-support:2.0.1-SNAPSHOT'
-compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.1-SNAPSHOT'
+compile 'com.bluelinelabs:conductor:2.0.5-SNAPSHOT'
+compile 'com.bluelinelabs:conductor-support:2.0.5-SNAPSHOT'
+compile 'com.bluelinelabs:conductor-rxlifecycle:2.0.5-SNAPSHOT'
+```
+
+You also have to add the url to the snapshot repository:
+
+```gradle
+allprojects {
+  repositories {
+    ...
+
+    maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
+}
 ```
 
 ## Components to Know
@@ -114,7 +125,7 @@ The lifecycle of a Controller is significantly simpler to understand than that o
 `ControllerChangeHandler` can be subclassed in order to perform different functions when changing between two `Controllers`. Two convenience `ControllerChangeHandler` subclasses are included to cover most basic needs: `AnimatorChangeHandler`, which will use an `Animator` object to transition between two views, and `TransitionChangeHandler`, which will use Lollipop's `Transition` framework for transitioning between views.
 
 ### Child Routers & Controllers
-`getChildController` 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.
+`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.

build.gradle

@@ -3,7 +3,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.1.2'
+        classpath 'com.android.tools.build:gradle:2.2.2'
     }
 }
 

conductor-rxlifecycle/build.gradle

@@ -28,6 +28,7 @@ dependencies {
     compile rootProject.ext.rxJava
     compile rootProject.ext.rxAndroid
     compile rootProject.ext.rxLifecycle
+    compile rootProject.ext.rxLifecycleAndroid
 
     compile project(':conductor')
 }

conductor-rxlifecycle/src/main/java/com/bluelinelabs/conductor/rxlifecycle/ControllerLifecycleProvider.java

@@ -1,38 +0,0 @@
-package com.bluelinelabs.conductor.rxlifecycle;
-
-import android.support.annotation.CheckResult;
-import android.support.annotation.NonNull;
-
-import rx.Observable;
-
-/**
- * Interface used for RxController. Can also be used if writing your own Controller component without subclassing RxController.
- */
-public interface ControllerLifecycleProvider {
-
-    /**
-     * @return An observable that will have all {@link com.bluelinelabs.conductor.Controller} lifecycle events
-     */
-    @NonNull
-    @CheckResult
-    Observable<ControllerEvent> lifecycle();
-
-    /**
-     * Will bind the source until a specific {@link ControllerEvent} occurs.
-     *
-     * @param event The {@link ControllerEvent} that should cause onComplete to be called
-     * @return A {@link rx.Observable.Transformer} that will call onComplete when the event occurs.
-     */
-    @NonNull
-    @CheckResult
-    <T> Observable.Transformer<T, T> bindUntilEvent(@NonNull ControllerEvent event);
-
-    /**
-     * Will bind the source until the next reasonable {@link ControllerEvent} occurs.
-     * @return A {@link rx.Observable.Transformer} that will call onComplete when the event occurs.
-     */
-    @NonNull
-    @CheckResult
-    <T> Observable.Transformer<T, T> bindToLifecycle();
-
-}

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

@@ -5,6 +5,8 @@ import android.support.annotation.CheckResult;
 import android.support.annotation.NonNull;
 
 import com.bluelinelabs.conductor.Controller;
+import com.trello.rxlifecycle.LifecycleProvider;
+import com.trello.rxlifecycle.LifecycleTransformer;
 import com.trello.rxlifecycle.RxLifecycle;
 
 import rx.Observable;
@@ -13,7 +15,7 @@ import rx.subjects.BehaviorSubject;
 /**
  * A base {@link Controller} that can be used to expose lifecycle events using RxJava
  */
-public abstract class RxController extends Controller implements ControllerLifecycleProvider {
+public abstract class RxController extends Controller implements LifecycleProvider<ControllerEvent> {
 
     private final BehaviorSubject<ControllerEvent> lifecycleSubject;
 
@@ -36,14 +38,14 @@ public abstract class RxController extends Controller implements ControllerLifec
     @Override
     @NonNull
     @CheckResult
-    public final <T> Observable.Transformer<T, T> bindUntilEvent(@NonNull ControllerEvent event) {
+    public final <T> LifecycleTransformer<T> bindUntilEvent(@NonNull ControllerEvent event) {
         return RxLifecycle.bindUntilEvent(lifecycleSubject, event);
     }
 
     @Override
     @NonNull
     @CheckResult
-    public final <T> Observable.Transformer<T, T> bindToLifecycle() {
+    public final <T> LifecycleTransformer<T> bindToLifecycle() {
         return RxControllerLifecycle.bindController(lifecycleSubject);
     }
 

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

@@ -14,7 +14,7 @@ public class RxControllerLifecycle {
 
     /**
      * Binds the given source to a Controller lifecycle. This is the Controller version of
-     * {@link com.trello.rxlifecycle.RxLifecycle#bindFragment(Observable)}.
+     * {@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

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

@@ -0,0 +1,52 @@
+package com.bluelinelabs.conductor.rxlifecycle;
+
+import android.os.Bundle;
+import android.support.annotation.CheckResult;
+import android.support.annotation.NonNull;
+
+import com.bluelinelabs.conductor.RestoreViewOnCreateController;
+import com.trello.rxlifecycle.LifecycleProvider;
+import com.trello.rxlifecycle.LifecycleTransformer;
+import com.trello.rxlifecycle.RxLifecycle;
+
+import rx.Observable;
+import rx.subjects.BehaviorSubject;
+
+/**
+ * A base {@link RestoreViewOnCreateController} that can be used to expose lifecycle events using RxJava
+ */
+public abstract class RxRestoreViewOnCreateController extends RestoreViewOnCreateController implements LifecycleProvider<ControllerEvent> {
+
+    private final BehaviorSubject<ControllerEvent> lifecycleSubject;
+
+    public RxRestoreViewOnCreateController() {
+        this(null);
+    }
+
+    public RxRestoreViewOnCreateController(Bundle args) {
+        super(args);
+        lifecycleSubject = ControllerLifecycleSubjectHelper.create(this);
+    }
+
+    @Override
+    @NonNull
+    @CheckResult
+    public final Observable<ControllerEvent> lifecycle() {
+        return lifecycleSubject.asObservable();
+    }
+
+    @Override
+    @NonNull
+    @CheckResult
+    public final <T> LifecycleTransformer<T> bindUntilEvent(@NonNull ControllerEvent event) {
+        return RxLifecycle.bindUntilEvent(lifecycleSubject, event);
+    }
+
+    @Override
+    @NonNull
+    @CheckResult
+    public final <T> LifecycleTransformer<T> bindToLifecycle() {
+        return RxControllerLifecycle.bindController(lifecycleSubject);
+    }
+
+}

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

@@ -4,6 +4,7 @@ import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
@@ -30,13 +31,13 @@ public class ActivityHostedRouter extends Router {
         }
     }
 
-    @Override
+    @Override @Nullable
     public Activity getActivity() {
         return lifecycleHandler != null ? lifecycleHandler.getLifecycleActivity() : null;
     }
 
     @Override
-    public void onActivityDestroyed(Activity activity) {
+    public void onActivityDestroyed(@NonNull Activity activity) {
         super.onActivityDestroyed(activity);
         lifecycleHandler = null;
     }
@@ -49,37 +50,37 @@ public class ActivityHostedRouter extends Router {
     }
 
     @Override
-    public void onActivityResult(int requestCode, int resultCode, Intent data) {
+    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
         lifecycleHandler.onActivityResult(requestCode, resultCode, data);
     }
 
     @Override
-    void startActivity(Intent intent) {
+    void startActivity(@NonNull Intent intent) {
         lifecycleHandler.startActivity(intent);
     }
 
     @Override
-    void startActivityForResult(String instanceId, Intent intent, int requestCode) {
+    void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode) {
         lifecycleHandler.startActivityForResult(instanceId, intent, requestCode);
     }
 
     @Override
-    void startActivityForResult(String instanceId, Intent intent, int requestCode, Bundle options) {
+    void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode, @Nullable Bundle options) {
         lifecycleHandler.startActivityForResult(instanceId, intent, requestCode, options);
     }
 
     @Override
-    void registerForActivityResult(String instanceId, int requestCode) {
+    void registerForActivityResult(@NonNull String instanceId, int requestCode) {
         lifecycleHandler.registerForActivityResult(instanceId, requestCode);
     }
 
     @Override
-    void unregisterForActivityResults(String instanceId) {
+    void unregisterForActivityResults(@NonNull String instanceId) {
         lifecycleHandler.unregisterForActivityResults(instanceId);
     }
 
     @Override
-    void requestPermissions(String instanceId, @NonNull String[] permissions, int requestCode) {
+    void requestPermissions(@NonNull String instanceId, @NonNull String[] permissions, int requestCode) {
         lifecycleHandler.requestPermissions(instanceId, permissions, requestCode);
     }
 
@@ -88,8 +89,13 @@ public class ActivityHostedRouter extends Router {
         return lifecycleHandler != null;
     }
 
-    @Override
+    @Override @NonNull
     List<Router> getSiblingRouters() {
         return lifecycleHandler.getRouters();
     }
+
+    @Override @NonNull
+    Router getRootRouter() {
+        return this;
+    }
 }

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

@@ -1,6 +1,8 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
 import java.util.ArrayDeque;
 import java.util.ArrayList;
@@ -24,20 +26,23 @@ class Backstack implements Iterable<RouterTransaction> {
         return backStack.size();
     }
 
+    @Nullable
     public RouterTransaction root() {
         return backStack.size() > 0 ? backStack.getLast() : null;
     }
 
-    @Override
+    @Override @NonNull
     public Iterator<RouterTransaction> iterator() {
         return backStack.iterator();
     }
 
+    @NonNull
     public Iterator<RouterTransaction> reverseIterator() {
         return backStack.descendingIterator();
     }
 
-    public List<RouterTransaction> popTo(RouterTransaction transaction) {
+    @NonNull
+    public List<RouterTransaction> popTo(@NonNull RouterTransaction transaction) {
         List<RouterTransaction> popped = new ArrayList<>();
         if (backStack.contains(transaction)) {
             while (backStack.peek() != transaction) {
@@ -50,24 +55,27 @@ class Backstack implements Iterable<RouterTransaction> {
         return popped;
     }
 
+    @NonNull
     public RouterTransaction pop() {
         RouterTransaction popped = backStack.pop();
         popped.controller.destroy();
         return popped;
     }
 
+    @Nullable
     public RouterTransaction peek() {
         return backStack.peek();
     }
 
-    public void remove(RouterTransaction transaction) {
+    public void remove(@NonNull RouterTransaction transaction) {
         backStack.removeFirstOccurrence(transaction);
     }
 
-    public void push(RouterTransaction transaction) {
+    public void push(@NonNull RouterTransaction transaction) {
         backStack.push(transaction);
     }
 
+    @NonNull
     public List<RouterTransaction> popAll() {
         List<RouterTransaction> list = new ArrayList<>();
         while (!isEmpty()) {
@@ -76,7 +84,7 @@ class Backstack implements Iterable<RouterTransaction> {
         return list;
     }
 
-    public void setBackstack(List<RouterTransaction> backstack) {
+    public void setBackstack(@NonNull List<RouterTransaction> backstack) {
         for (RouterTransaction existingTransaction : backStack) {
             boolean contains = false;
             for (RouterTransaction newTransaction : backstack) {
@@ -97,7 +105,7 @@ class Backstack implements Iterable<RouterTransaction> {
         }
     }
 
-    public void saveInstanceState(Bundle outState) {
+    public void saveInstanceState(@NonNull Bundle outState) {
         ArrayList<Bundle> entryBundles = new ArrayList<>(backStack.size());
         for (RouterTransaction entry : backStack) {
             entryBundles.add(entry.saveInstanceState());
@@ -106,7 +114,7 @@ class Backstack implements Iterable<RouterTransaction> {
         outState.putParcelableArrayList(KEY_ENTRIES, entryBundles);
     }
 
-    public void restoreInstanceState(Bundle savedInstanceState) {
+    public 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

@@ -3,6 +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 android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.ViewGroup;
@@ -42,12 +44,12 @@ public class ChangeHandlerFrameLayout extends FrameLayout implements ControllerC
     }
 
     @Override
-    public void onChangeStarted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler) {
+    public void onChangeStarted(@Nullable Controller to, @Nullable Controller from, boolean isPush, @NonNull ViewGroup container, @NonNull ControllerChangeHandler handler) {
         inProgressTransactionCount++;
     }
 
     @Override
-    public void onChangeCompleted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler) {
+    public void onChangeCompleted(@Nullable Controller to, @Nullable Controller from, boolean isPush, @NonNull ViewGroup container, @NonNull ControllerChangeHandler handler) {
         inProgressTransactionCount--;
     }
 

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

@@ -3,6 +3,8 @@ 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 android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.internal.LifecycleHandler;
@@ -26,7 +28,8 @@ public final class Conductor {
      *                           for restoring the Router's state if possible.
      * @return A fully configured {@link Router} instance for use with this Activity/ViewGroup pair.
      */
-    public static Router attachRouter(@NonNull Activity activity, @NonNull ViewGroup container, Bundle savedInstanceState) {
+    @NonNull @UiThread
+    public static Router attachRouter(@NonNull Activity activity, @NonNull ViewGroup container, @Nullable Bundle savedInstanceState) {
         LifecycleHandler lifecycleHandler = LifecycleHandler.install(activity);
 
         Router router = lifecycleHandler.getRouter(container, savedInstanceState);

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

@@ -10,6 +10,7 @@ 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;
@@ -20,16 +21,15 @@ import android.view.View;
 import android.view.View.OnAttachStateChangeListener;
 import android.view.ViewGroup;
 
-import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
+import com.bluelinelabs.conductor.Router.OnControllerPushedListener;
 import com.bluelinelabs.conductor.internal.ClassUtils;
 import com.bluelinelabs.conductor.internal.RouterRequiringFunc;
 
+import java.lang.ref.WeakReference;
 import java.lang.reflect.Constructor;
-import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Deque;
-import java.util.Iterator;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.UUID;
 
@@ -54,10 +54,11 @@ public abstract class Controller {
     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";
+    private static final String KEY_RETAIN_VIEW_MODE = "Controller.retainViewMode";
 
     private final Bundle args;
 
-    private Bundle viewState;
+    Bundle viewState;
     private Bundle savedInstanceState;
     private boolean isBeingDestroyed;
     private boolean destroyed;
@@ -72,6 +73,7 @@ public abstract class Controller {
     private String instanceId;
     private String targetInstanceId;
     private boolean needsAttach;
+    private boolean attachedToUnownedParent;
     private boolean hasSavedViewState;
     private boolean isDetachFrozen;
     private ControllerChangeHandler overriddenPushHandler;
@@ -82,21 +84,18 @@ 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 Deque<Controller> childBackstack = new ArrayDeque<>();
+    private final List<Controller> childBackstack = new LinkedList<>();
+    private WeakReference<View> destroyedView;
 
-    private final ControllerChangeListener childRouterChangeListener = new ControllerChangeListener() {
+    private final OnControllerPushedListener onControllerPushedListener = new OnControllerPushedListener() {
         @Override
-        public void onChangeStarted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler) {
-            if (isPush) {
-                onChildControllerPushed(to);
-            }
+        public void onControllerPushed(Controller controller) {
+            onChildControllerPushed(controller);
         }
-
-        @Override
-        public void onChangeCompleted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler) { }
     };
 
-    static Controller newInstance(Bundle bundle) {
+    @NonNull
+    static Controller newInstance(@NonNull Bundle bundle) {
         final String className = bundle.getString(KEY_CLASS_NAME);
         //noinspection ConstantConditions
         Constructor[] constructors = ClassUtils.classForName(className, false).getConstructors();
@@ -130,7 +129,7 @@ public abstract class Controller {
      *
      * @param args Any arguments that need to be retained.
      */
-    protected Controller(Bundle args) {
+    protected Controller(@Nullable Bundle args) {
         this.args = args;
         instanceId = UUID.randomUUID().toString();
         ensureRequiredConstructor();
@@ -159,11 +158,34 @@ public abstract class Controller {
     /**
      * Returns any arguments that were set in this Controller's constructor
      */
+    @Nullable
     public Bundle getArgs() {
         return args;
     }
 
-    public final Router getChildRouter(@NonNull ViewGroup container, String tag) {
+    /**
+     * Retrieves the child {@link Router} for the given container. If no child router for this container
+     * exists yet, it will be created.
+     *
+     * @param container The ViewGroup that hosts the child Router
+     */
+    @NonNull
+    public final Router getChildRouter(@NonNull ViewGroup container) {
+        //noinspection deprecation
+        return getChildRouter(container, null);
+    }
+
+    /**
+     * Retrieves the child {@link Router} for the given container/tag combination. If no child router for
+     * this container exists yet, it will be created. 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).
+     *
+     * @param container The ViewGroup that hosts the child Router
+     * @param tag The router's tag
+     */
+    @NonNull
+    public final Router getChildRouter(@NonNull ViewGroup container, @Nullable String tag) {
         @IdRes final int containerId = container.getId();
 
         ControllerHostedRouter childRouter = null;
@@ -218,6 +240,7 @@ public abstract class Controller {
     /**
      * Return this Controller's View, if available.
      */
+    @Nullable
     public final View getView() {
         return view;
     }
@@ -225,6 +248,7 @@ public abstract class Controller {
     /**
      * Returns the host Activity of this Controller's {@link Router}
      */
+    @Nullable
     public final Activity getActivity() {
         return router.getActivity();
     }
@@ -232,6 +256,7 @@ public abstract class Controller {
     /**
      * Returns the Resources from the host Activity
      */
+    @Nullable
     public final Resources getResources() {
         Activity activity = getActivity();
         return activity != null ? activity.getResources() : null;
@@ -240,6 +265,7 @@ public abstract class Controller {
     /**
      * Returns the Application Context derived from the host Activity
      */
+    @Nullable
     public final Context getApplicationContext() {
         Activity activity = getActivity();
         return activity != null ? activity.getApplicationContext() : null;
@@ -248,6 +274,7 @@ public abstract class Controller {
     /**
      * Returns this Controller's parent Controller if it is a child Controller.
      */
+    @Nullable
     public final Controller getParentController() {
         return parentController;
     }
@@ -256,6 +283,7 @@ public abstract class Controller {
      * Returns this Controller's instance ID, which is generated when the instance is created and
      * retained across restarts.
      */
+    @NonNull
     public final String getInstanceId() {
         return instanceId;
     }
@@ -266,7 +294,8 @@ public abstract class Controller {
      * @param instanceId The instance ID being searched for
      * @return The matching Controller, if one exists
      */
-    final Controller findController(String instanceId) {
+    @Nullable
+    final Controller findController(@NonNull String instanceId) {
         if (this.instanceId.equals(instanceId)) {
             return this;
         }
@@ -283,6 +312,7 @@ public abstract class Controller {
     /**
      * Returns all of this Controller's child Routers
      */
+    @NonNull
     public final List<Router> getChildRouters() {
         List<Router> routers = new ArrayList<>();
         for (Router router : childRouters) {
@@ -298,7 +328,7 @@ public abstract class Controller {
      *
      * @param target The Controller that is the target of this one.
      */
-    public void setTargetController(Controller target) {
+    public void setTargetController(@Nullable Controller target) {
         if (targetInstanceId != null) {
             throw new RuntimeException("Target controller already set. A controller's target may only be set once.");
         }
@@ -311,8 +341,12 @@ public abstract class Controller {
      *
      * @return This Controller's target
      */
+    @Nullable
     public final Controller getTargetController() {
-        return targetInstanceId != null ? router.getControllerWithInstanceId(targetInstanceId) : null;
+        if (targetInstanceId != null) {
+            return router.getRootRouter().getControllerWithInstanceId(targetInstanceId);
+        }
+        return null;
     }
 
     /**
@@ -321,7 +355,7 @@ public abstract class Controller {
      *
      * @param view The View to which this Controller should be bound.
      */
-    protected void onDestroyView(View view) { }
+    protected void onDestroyView(@NonNull View view) { }
 
     /**
      * Called when this Controller begins the process of being swapped in or out of the host view.
@@ -361,22 +395,22 @@ public abstract class Controller {
     /**
      * Called when this Controller's host Activity is started
      */
-    protected void onActivityStarted(Activity activity) { }
+    protected void onActivityStarted(@NonNull Activity activity) { }
 
     /**
      * Called when this Controller's host Activity is resumed
      */
-    protected void onActivityResumed(Activity activity) { }
+    protected void onActivityResumed(@NonNull Activity activity) { }
 
     /**
      * Called when this Controller's host Activity is paused
      */
-    protected void onActivityPaused(Activity activity) { }
+    protected void onActivityPaused(@NonNull Activity activity) { }
 
     /**
      * Called when this Controller's host Activity is stopped
      */
-    protected void onActivityStopped(Activity activity) { }
+    protected void onActivityStopped(@NonNull Activity activity) { }
 
     /**
      * Called to save this Controller's View state. As Views can be detached and destroyed as part of the
@@ -415,7 +449,7 @@ public abstract class Controller {
     /**
      * Calls startActivity(Intent) from this Controller's host Activity.
      */
-    public final void startActivity(final Intent intent) {
+    public final void startActivity(@NonNull final Intent intent) {
         executeWithRouter(new RouterRequiringFunc() {
             @Override public void execute() { router.startActivity(intent); }
         });
@@ -424,7 +458,7 @@ public abstract class Controller {
     /**
      * Calls startActivityForResult(Intent, int) from this Controller's host Activity.
      */
-    public final void startActivityForResult(final Intent intent, final int requestCode) {
+    public final void startActivityForResult(@NonNull final Intent intent, final int requestCode) {
         executeWithRouter(new RouterRequiringFunc() {
             @Override public void execute() { router.startActivityForResult(instanceId, intent, requestCode); }
         });
@@ -433,7 +467,7 @@ public abstract class Controller {
     /**
      * Calls startActivityForResult(Intent, int, Bundle) from this Controller's host Activity.
      */
-    public final void startActivityForResult(final Intent intent, final int requestCode, final Bundle options) {
+    public final void startActivityForResult(@NonNull final Intent intent, final int requestCode, @Nullable final Bundle options) {
         executeWithRouter(new RouterRequiringFunc() {
             @Override public void execute() { router.startActivityForResult(instanceId, intent, requestCode, options); }
         });
@@ -459,7 +493,7 @@ public abstract class Controller {
      * @param resultCode  The resultCode that was returned to the host Activity's onActivityResult method
      * @param data        The data Intent that was returned to the host Activity's onActivityResult method
      */
-    public void onActivityResult(int requestCode, int resultCode, Intent data) { }
+    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) { }
 
     /**
      * Calls requestPermission(String[], int) from this Controller's host Activity. Results for this request,
@@ -500,9 +534,8 @@ public abstract class Controller {
      * @return True if this Controller has consumed the back button press, otherwise false
      */
     public boolean handleBack() {
-        Iterator<Controller> childIterator = childBackstack.descendingIterator();
-        while (childIterator.hasNext()) {
-            Controller childController = childIterator.next();
+        for (int i = childBackstack.size() - 1; i >= 0; i--) {
+            Controller childController = childBackstack.get(i);
             if (childController.isAttached() && childController.getRouter().handleBack()) {
                 return true;
             }
@@ -516,7 +549,7 @@ public abstract class Controller {
      *
      * @param lifecycleListener The listener
      */
-    public void addLifecycleListener(LifecycleListener lifecycleListener) {
+    public void addLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
         if (!lifecycleListeners.contains(lifecycleListener)) {
             lifecycleListeners.add(lifecycleListener);
         }
@@ -527,13 +560,14 @@ public abstract class Controller {
      *
      * @param lifecycleListener The listener to be removed
      */
-    public void removeLifecycleListener(LifecycleListener lifecycleListener) {
+    public void removeLifecycleListener(@NonNull LifecycleListener lifecycleListener) {
         lifecycleListeners.remove(lifecycleListener);
     }
 
     /**
      * Returns this Controller's {@link RetainViewMode}. Defaults to {@link RetainViewMode#RELEASE_DETACH}.
      */
+    @NonNull
     public RetainViewMode getRetainViewMode() {
         return retainViewMode;
     }
@@ -542,8 +576,8 @@ public abstract class Controller {
      * Sets this Controller's {@link RetainViewMode}, which will influence when its view will be released.
      * This is useful when a Controller's view hierarchy is expensive to tear down and rebuild.
      */
-    public void setRetainViewMode(RetainViewMode retainViewMode) {
-        this.retainViewMode = retainViewMode;
+    public void setRetainViewMode(@NonNull RetainViewMode retainViewMode) {
+        this.retainViewMode = retainViewMode != null ? retainViewMode : RetainViewMode.RELEASE_DETACH;
         if (this.retainViewMode == RetainViewMode.RELEASE_DETACH && !attached) {
             removeViewReference();
         }
@@ -553,6 +587,7 @@ public abstract class Controller {
      * Returns the {@link ControllerChangeHandler} that should be used for pushing this Controller, or null
      * if the handler from the {@link RouterTransaction} should be used instead.
      */
+    @Nullable
     public final ControllerChangeHandler getOverriddenPushHandler() {
         return overriddenPushHandler;
     }
@@ -561,7 +596,7 @@ public abstract class Controller {
      * Overrides the {@link ControllerChangeHandler} that should be used for pushing this Controller. If this is a
      * non-null value, it will be used instead of the handler from  the {@link RouterTransaction}.
      */
-    public void overridePushHandler(ControllerChangeHandler overriddenPushHandler) {
+    public void overridePushHandler(@Nullable ControllerChangeHandler overriddenPushHandler) {
         this.overriddenPushHandler = overriddenPushHandler;
     }
 
@@ -569,6 +604,7 @@ public abstract class Controller {
      * Returns the {@link ControllerChangeHandler} that should be used for popping this Controller, or null
      * if the handler from the {@link RouterTransaction} should be used instead.
      */
+    @Nullable
     public ControllerChangeHandler getOverriddenPopHandler() {
         return overriddenPopHandler;
     }
@@ -577,7 +613,7 @@ public abstract class Controller {
      * Overrides the {@link ControllerChangeHandler} that should be used for popping this Controller. If this is a
      * non-null value, it will be used instead of the handler from  the {@link RouterTransaction}.
      */
-    public void overridePopHandler(ControllerChangeHandler overriddenPopHandler) {
+    public void overridePopHandler(@Nullable ControllerChangeHandler overriddenPopHandler) {
         this.overriddenPopHandler = overriddenPopHandler;
     }
 
@@ -621,7 +657,7 @@ public abstract class Controller {
      * @param menu The menu into which your options should be placed.
      * @param inflater The inflater that can be used to inflate your menu items.
      */
-    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { }
+    public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) { }
 
     /**
      * Prepare the screen's options menu to be displayed. This is called directly before showing the
@@ -629,7 +665,7 @@ public abstract class Controller {
      *
      * @param menu The menu that will be displayed
      */
-    public void onPrepareOptionsMenu(Menu menu) { }
+    public void onPrepareOptionsMenu(@NonNull Menu menu) { }
 
     /**
      * Called when an option menu item has been selected by the user.
@@ -637,10 +673,14 @@ public abstract class Controller {
      * @param item The selected item.
      * @return True if this event has been consumed, false if it has not.
      */
-    public boolean onOptionsItemSelected(MenuItem item) {
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
         return false;
     }
 
+    final void setNeedsAttach() {
+        needsAttach = true;
+    }
+
     final void prepareForHostDetach() {
         needsAttach = needsAttach || attached;
 
@@ -685,23 +725,25 @@ public abstract class Controller {
         }
     }
 
-    final void activityStarted(Activity activity) {
+    final void activityStarted(@NonNull Activity activity) {
         onActivityStarted(activity);
     }
 
-    final void activityResumed(Activity activity) {
+    final void activityResumed(@NonNull Activity activity) {
         if (!attached && view != null && viewIsAttached) {
             attach(view);
+        } else if (attached) {
+            needsAttach = false;
         }
 
         onActivityResumed(activity);
     }
 
-    final void activityPaused(Activity activity) {
+    final void activityPaused(@NonNull Activity activity) {
         onActivityPaused(activity);
     }
 
-    final void activityStopped(Activity activity) {
+    final void activityStopped(@NonNull Activity activity) {
         onActivityStopped(activity);
     }
 
@@ -714,9 +756,15 @@ public abstract class Controller {
     }
 
     private void attach(@NonNull View view) {
+        attachedToUnownedParent = router == null || view.getParent() != router.container;
+        if (attachedToUnownedParent) {
+            return;
+        }
+
         hasSavedViewState = false;
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.preAttach(this, view);
         }
 
@@ -729,20 +777,24 @@ public abstract class Controller {
             router.invalidateOptionsMenu();
         }
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.postAttach(this, view);
         }
     }
 
-    private void detach(@NonNull View view, boolean forceViewRefRemoval) {
-        for (ControllerHostedRouter router : childRouters) {
-            router.prepareForHostDetach();
+    void detach(@NonNull View view, boolean forceViewRefRemoval) {
+        if (!attachedToUnownedParent) {
+            for (ControllerHostedRouter router : childRouters) {
+                router.prepareForHostDetach();
+            }
         }
 
         final boolean removeViewRef = forceViewRefRemoval || retainViewMode == RetainViewMode.RELEASE_DETACH || isBeingDestroyed;
 
         if (attached) {
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.preDetach(this, view);
             }
 
@@ -753,7 +805,8 @@ public abstract class Controller {
                 router.invalidateOptionsMenu();
             }
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.postDetach(this, view);
             }
         }
@@ -769,7 +822,8 @@ public abstract class Controller {
                 saveViewState(view);
             }
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.preDestroyView(this, view);
             }
 
@@ -777,9 +831,14 @@ public abstract class Controller {
 
             view.removeOnAttachStateChangeListener(onAttachStateChangeListener);
             viewIsAttached = false;
+
+            if (isBeingDestroyed) {
+                destroyedView = new WeakReference<>(view);
+            }
             view = null;
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.postDestroyView(this);
             }
 
@@ -800,13 +859,15 @@ public abstract class Controller {
         }
 
         if (view == null) {
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.preCreateView(this);
             }
 
             view = onCreateView(LayoutInflater.from(parent.getContext()), parent);
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.postCreateView(this, view);
             }
 
@@ -839,23 +900,21 @@ public abstract class Controller {
         return view;
     }
 
-    final void performDestroy() {
+    private void performDestroy() {
         if (!destroyed) {
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.preDestroy(this);
             }
 
             destroyed = true;
 
-            if (router != null) {
-                router.unregisterForActivityResults(instanceId);
-            }
-
             onDestroy();
 
             parentController = null;
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.postDestroy(this);
             }
         }
@@ -865,9 +924,13 @@ public abstract class Controller {
         destroy(false);
     }
 
-    final void destroy(boolean removeViews) {
+    private void destroy(boolean removeViews) {
         isBeingDestroyed = true;
 
+        if (router != null) {
+            router.unregisterForActivityResults(instanceId);
+        }
+
         for (ControllerHostedRouter childRouter : childRouters) {
             childRouter.destroy();
         }
@@ -875,11 +938,11 @@ public abstract class Controller {
         if (!attached) {
             removeViewReference();
         } else if (removeViews) {
-            detach(view, false);
+            detach(view, true);
         }
     }
 
-    final void saveViewState(@NonNull View view) {
+    private void saveViewState(@NonNull View view) {
         hasSavedViewState = true;
 
         viewState = new Bundle();
@@ -892,12 +955,13 @@ public abstract class Controller {
         onSaveViewState(view, stateBundle);
         viewState.putBundle(KEY_VIEW_STATE_BUNDLE, stateBundle);
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.onSaveViewState(this, viewState);
         }
     }
 
-    final void restoreViewState(@NonNull View view) {
+    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));
@@ -908,12 +972,14 @@ public abstract class Controller {
 
                     if (containerView != null && containerView instanceof ViewGroup) {
                         childRouter.setHost(this, (ViewGroup)containerView);
+                        monitorChildRouter(childRouter);
                         childRouter.rebindIfNeeded();
                     }
                 }
             }
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.onRestoreViewState(this, viewState);
             }
         }
@@ -932,6 +998,7 @@ public abstract class Controller {
         outState.putString(KEY_TARGET_INSTANCE_ID, targetInstanceId);
         outState.putStringArrayList(KEY_REQUESTED_PERMISSIONS, requestedPermissions);
         outState.putBoolean(KEY_NEEDS_ATTACH, needsAttach || attached);
+        outState.putInt(KEY_RETAIN_VIEW_MODE, retainViewMode.ordinal());
 
         if (overriddenPushHandler != null) {
             outState.putBundle(KEY_OVERRIDDEN_PUSH_HANDLER, overriddenPushHandler.toBundle());
@@ -951,7 +1018,8 @@ public abstract class Controller {
         Bundle savedState = new Bundle();
         onSaveInstanceState(savedState);
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.onSaveInstanceState(this, savedState);
         }
 
@@ -968,6 +1036,7 @@ public abstract class Controller {
         overriddenPushHandler = ControllerChangeHandler.fromBundle(savedInstanceState.getBundle(KEY_OVERRIDDEN_PUSH_HANDLER));
         overriddenPopHandler = ControllerChangeHandler.fromBundle(savedInstanceState.getBundle(KEY_OVERRIDDEN_POP_HANDLER));
         needsAttach = savedInstanceState.getBoolean(KEY_NEEDS_ATTACH);
+        retainViewMode = RetainViewMode.values()[savedInstanceState.getInt(KEY_RETAIN_VIEW_MODE, 0)];
 
         List<Bundle> childBundles = savedInstanceState.getParcelableArrayList(KEY_CHILD_ROUTERS);
         for (Bundle childBundle : childBundles) {
@@ -985,7 +1054,8 @@ public abstract class Controller {
         if (savedInstanceState != null && router != null) {
             onRestoreInstanceState(savedInstanceState);
 
-            for (LifecycleListener lifecycleListener : lifecycleListeners) {
+            List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+            for (LifecycleListener lifecycleListener : listeners) {
                 lifecycleListener.onRestoreInstanceState(this, savedInstanceState);
             }
 
@@ -993,7 +1063,7 @@ public abstract class Controller {
         }
     }
 
-    final void changeStarted(ControllerChangeHandler changeHandler, ControllerChangeType changeType) {
+    final void changeStarted(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
         if (!changeType.isEnter) {
             for (ControllerHostedRouter router : childRouters) {
                 router.setDetachFrozen(true);
@@ -1002,12 +1072,13 @@ public abstract class Controller {
 
         onChangeStarted(changeHandler, changeType);
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.onChangeStart(this, changeHandler, changeType);
         }
     }
 
-    final void changeEnded(ControllerChangeHandler changeHandler, ControllerChangeType changeType) {
+    final void changeEnded(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
         if (!changeType.isEnter) {
             for (ControllerHostedRouter router : childRouters) {
                 router.setDetachFrozen(false);
@@ -1016,9 +1087,18 @@ public abstract class Controller {
 
         onChangeEnded(changeHandler, changeType);
 
-        for (LifecycleListener lifecycleListener : lifecycleListeners) {
+        List<LifecycleListener> listeners = new ArrayList<>(lifecycleListeners);
+        for (LifecycleListener lifecycleListener : listeners) {
             lifecycleListener.onChangeEnd(this, changeHandler, changeType);
         }
+
+        if (isBeingDestroyed && !viewIsAttached && !attached && destroyedView != null) {
+            View view = destroyedView.get();
+            if (router.container != null && view != null && view.getParent() == router.container) {
+                router.container.removeView(view);
+            }
+            destroyedView = null;
+        }
     }
 
     final void setDetachFrozen(boolean frozen) {
@@ -1035,46 +1115,39 @@ public abstract class Controller {
         }
     }
 
-    final void createOptionsMenu(Menu menu, MenuInflater inflater) {
-        if (attached) {
-            if (hasOptionsMenu && !optionsMenuHidden) {
-                onCreateOptionsMenu(menu, inflater);
-            }
+    final void createOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
+        if (attached && hasOptionsMenu && !optionsMenuHidden) {
+            onCreateOptionsMenu(menu, inflater);
         }
     }
 
-    final void prepareOptionsMenu(Menu menu) {
-        if (attached) {
-            if (hasOptionsMenu && !optionsMenuHidden) {
-                onPrepareOptionsMenu(menu);
-            }
+    final void prepareOptionsMenu(@NonNull Menu menu) {
+        if (attached && hasOptionsMenu && !optionsMenuHidden) {
+            onPrepareOptionsMenu(menu);
         }
     }
 
-    final boolean optionsItemSelected(MenuItem item) {
-        if (attached) {
-            if (hasOptionsMenu && !optionsMenuHidden && onOptionsItemSelected(item)) {
-                return true;
-            }
+    final boolean optionsItemSelected(@NonNull MenuItem item) {
+        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);
+                }
+            });
         }
-        return false;
     }
 
-    private void monitorChildRouter(ControllerHostedRouter childRouter) {
-        childRouter.addChangeListener(childRouterChangeListener);
-    }
-
-    private void onChildControllerPushed(Controller controller) {
-        childBackstack.add(controller);
-        controller.addLifecycleListener(new LifecycleListener() {
-            @Override
-            public void postDestroy(@NonNull Controller controller) {
-                childBackstack.remove(controller);
-            }
-        });
-    }
-
-    final void setParentController(Controller controller) {
+    final void setParentController(@Nullable Controller controller) {
         parentController = controller;
     }
 
@@ -1085,7 +1158,8 @@ public abstract class Controller {
         }
     }
 
-    private static Constructor getDefaultConstructor(Constructor[] constructors) {
+    @Nullable
+    private static Constructor getDefaultConstructor(@NonNull Constructor[] constructors) {
         for (Constructor constructor : constructors) {
             if (constructor.getParameterTypes().length == 0) {
                 return constructor;
@@ -1094,7 +1168,8 @@ public abstract class Controller {
         return null;
     }
 
-    private static Constructor getBundleConstructor(Constructor[] constructors) {
+    @Nullable
+    private static Constructor getBundleConstructor(@NonNull Constructor[] constructors) {
         for (Constructor constructor : constructors) {
             if (constructor.getParameterTypes().length == 1 && constructor.getParameterTypes()[0] == Bundle.class) {
                 return constructor;
@@ -1137,6 +1212,7 @@ public abstract class Controller {
 
         public void onSaveViewState(@NonNull Controller controller, @NonNull Bundle outState) { }
         public void onRestoreViewState(@NonNull Controller controller, @NonNull Bundle savedViewState) { }
+
     }
 
 }

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

@@ -2,8 +2,10 @@ package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
+import android.view.ViewParent;
 
 import com.bluelinelabs.conductor.changehandler.SimpleSwapChangeHandler;
 import com.bluelinelabs.conductor.internal.ClassUtils;
@@ -25,16 +27,18 @@ public abstract class ControllerChangeHandler {
 
     private static final Map<String, ControllerChangeHandler> inProgressPushHandlers = new HashMap<>();
 
+    private boolean forceRemoveViewOnPush;
+
     /**
      * 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 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, 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 changeListener This listener must be called when any transitions or animations are completed.
      */
-    public abstract void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener);
+    public abstract void performChange(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener);
 
     public ControllerChangeHandler() {
         ensureDefaultConstructor();
@@ -59,10 +63,17 @@ public abstract class ControllerChangeHandler {
      * 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 newTop     the controller that will now be at the top of the backstack
      */
-    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, Controller newTop) { }
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) { }
 
+    /**
+     * Will be called on change handlers that push a controller if the controller being pushed is
+     * needs to be attached immediately, without any animations or transitions.
+     */
+    public void completeImmediately() { }
+
+    @NonNull
     final Bundle toBundle() {
         Bundle bundle = new Bundle();
         bundle.putString(KEY_CLASS_NAME, getClass().getName());
@@ -74,6 +85,11 @@ public abstract class ControllerChangeHandler {
         return bundle;
     }
 
+    @NonNull
+    final ControllerChangeHandler copy() {
+        return fromBundle(toBundle());
+    }
+
     private void ensureDefaultConstructor() {
         try {
             getClass().getConstructor();
@@ -82,7 +98,8 @@ public abstract class ControllerChangeHandler {
         }
     }
 
-    public static ControllerChangeHandler fromBundle(Bundle bundle) {
+    @Nullable
+    public static ControllerChangeHandler fromBundle(@Nullable Bundle bundle) {
         if (bundle != null) {
             String className = bundle.getString(KEY_CLASS_NAME);
             ControllerChangeHandler changeHandler = ClassUtils.newInstance(className);
@@ -94,26 +111,44 @@ public abstract class ControllerChangeHandler {
         }
     }
 
-    public static void executeChange(final Controller to, final Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler inHandler) {
+    static boolean completePushImmediately(@NonNull String controllerInstanceId) {
+        ControllerChangeHandler changeHandler = inProgressPushHandlers.get(controllerInstanceId);
+        if (changeHandler != null) {
+            changeHandler.completeImmediately();
+            inProgressPushHandlers.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());
+        }
+    }
+
+    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>());
     }
 
-    public static void executeChange(final Controller to, final Controller from, final boolean isPush, final ViewGroup container, final ControllerChangeHandler inHandler, @NonNull final List<ControllerChangeListener> 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 (container != null) {
             final ControllerChangeHandler handler = inHandler != null ? inHandler : new SimpleSwapChangeHandler();
 
-            if (isPush) {
+            if (isPush && to != null) {
                 inProgressPushHandlers.put(to.getInstanceId(), handler);
-            } else if (from != null) {
-                ControllerChangeHandler handlerForPush = inProgressPushHandlers.get(from.getInstanceId());
-                if (handlerForPush != null) {
-                    handlerForPush.onAbortPush(handler, to);
-                    inProgressPushHandlers.remove(from.getInstanceId());
+
+                if (from != null) {
+                    completePushImmediately(from.getInstanceId());
                 }
+            } else if (!isPush && from != null) {
+                abortPush(from, to, handler);
             }
 
             for (ControllerChangeListener listener : listeners) {
-                listener.onChangeStarted(to, from, isPush, container, inHandler);
+                listener.onChangeStarted(to, from, isPush, container, handler);
             }
 
             final ControllerChangeType toChangeType = isPush ? ControllerChangeType.PUSH_ENTER : ControllerChangeType.POP_ENTER;
@@ -138,7 +173,6 @@ public abstract class ControllerChangeHandler {
             handler.performChange(container, fromView, toView, isPush, new ControllerChangeCompletedListener() {
                 @Override
                 public void onChangeCompleted() {
-
                     if (from != null) {
                         from.changeEnded(handler, fromChangeType);
                     }
@@ -149,13 +183,28 @@ public abstract class ControllerChangeHandler {
                     }
 
                     for (ControllerChangeListener listener : listeners) {
-                        listener.onChangeCompleted(to, from, isPush, container, inHandler);
+                        listener.onChangeCompleted(to, from, isPush, container, handler);
+                    }
+
+                    if (handler.forceRemoveViewOnPush && fromView != null) {
+                        ViewParent fromParent = fromView.getParent();
+                        if (fromParent != null && fromParent instanceof ViewGroup) {
+                            ((ViewGroup)fromParent).removeView(fromView);
+                        }
                     }
                 }
             });
         }
     }
 
+    public boolean removesFromViewOnPush() {
+        return true;
+    }
+
+    public void setForceRemoveViewOnPush(boolean force) {
+        forceRemoveViewOnPush = force;
+    }
+
     /**
      * A listener interface useful for allowing external classes to be notified of change events.
      */
@@ -163,23 +212,24 @@ 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 isPush True if this is a push operation, or false if it's a pop.
+         * @param to        The new Controller
+         * @param from      The old Controller
+         * @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.
+         * @param handler   The change handler being used.
          */
-        void onChangeStarted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler);
+        void onChangeStarted(@Nullable Controller to, @Nullable Controller from, boolean isPush, @NonNull ViewGroup container, @NonNull ControllerChangeHandler handler);
 
         /**
          * 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
+         * @param from      The old Controller
+         * @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.
+         * @param handler   The change handler that was used.
          */
-        void onChangeCompleted(Controller to, Controller from, boolean isPush, ViewGroup container, ControllerChangeHandler handler);
+        void onChangeCompleted(@Nullable Controller to, @Nullable Controller from, boolean isPush, @NonNull ViewGroup container, @NonNull ControllerChangeHandler handler);
     }
 
     /**

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

@@ -5,6 +5,7 @@ import android.content.Intent;
 import android.os.Bundle;
 import android.support.annotation.IdRes;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.ViewGroup;
 
 import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListener;
@@ -12,7 +13,7 @@ import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeListen
 import java.util.ArrayList;
 import java.util.List;
 
-public class ControllerHostedRouter extends Router {
+class ControllerHostedRouter extends Router {
 
     private final String KEY_HOST_ID = "ControllerHostedRouter.hostId";
     private final String KEY_TAG = "ControllerHostedRouter.tag";
@@ -22,14 +23,14 @@ public class ControllerHostedRouter extends Router {
     @IdRes private int hostId;
     private String tag;
 
-    public ControllerHostedRouter() { }
+    ControllerHostedRouter() { }
 
-    public ControllerHostedRouter(int hostId, String tag) {
+    ControllerHostedRouter(int hostId, @Nullable String tag) {
         this.hostId = hostId;
         this.tag = tag;
     }
 
-    public final void setHost(@NonNull Controller controller, @NonNull ViewGroup container) {
+    final void setHost(@NonNull Controller controller, @NonNull ViewGroup container) {
         if (hostController != controller || this.container != container) {
             removeHost();
 
@@ -42,36 +43,54 @@ public class ControllerHostedRouter extends Router {
         }
     }
 
-    public final void removeHost() {
+    final void removeHost() {
         if (container != null && container instanceof ControllerChangeListener) {
             removeChangeListener((ControllerChangeListener)container);
         }
 
+        final List<Controller> controllersToDestroy = new ArrayList<>(destroyingControllers);
+        for (Controller controller : controllersToDestroy) {
+            if (controller.getView() != null) {
+                controller.detach(controller.getView(), true);
+            }
+        }
+        for (RouterTransaction transaction : backstack) {
+            if (transaction.controller.getView() != null) {
+                transaction.controller.detach(transaction.controller.getView(), true);
+            }
+        }
+
         prepareForContainerRemoval();
         hostController = null;
         container = null;
     }
 
-    public final void setDetachFrozen(boolean frozen) {
-        for (RouterTransaction transaction : backStack) {
+    final void setDetachFrozen(boolean frozen) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.setDetachFrozen(frozen);
         }
     }
 
     @Override
+    void destroy() {
+        setDetachFrozen(false);
+        super.destroy();
+    }
+
+    @Override @Nullable
     public Activity getActivity() {
         return hostController != null ? hostController.getActivity() : null;
     }
 
     @Override
-    public void onActivityDestroyed(Activity activity) {
+    public void onActivityDestroyed(@NonNull Activity activity) {
         super.onActivityDestroyed(activity);
 
         removeHost();
     }
 
     @Override
-    public void onActivityResult(int requestCode, int resultCode, Intent data) {
+    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().onActivityResult(requestCode, resultCode, data);
         }
@@ -85,42 +104,42 @@ public class ControllerHostedRouter extends Router {
     }
 
     @Override
-    void startActivity(Intent intent) {
+    void startActivity(@NonNull Intent intent) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().startActivity(intent);
         }
     }
 
     @Override
-    void startActivityForResult(String instanceId, Intent intent, int requestCode) {
+    void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().startActivityForResult(instanceId, intent, requestCode);
         }
     }
 
     @Override
-    void startActivityForResult(String instanceId, Intent intent, int requestCode, Bundle options) {
+    void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode, @Nullable Bundle options) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().startActivityForResult(instanceId, intent, requestCode, options);
         }
     }
 
     @Override
-    void registerForActivityResult(String instanceId, int requestCode) {
+    void registerForActivityResult(@NonNull String instanceId, int requestCode) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().registerForActivityResult(instanceId, requestCode);
         }
     }
 
     @Override
-    void unregisterForActivityResults(String instanceId) {
+    void unregisterForActivityResults(@NonNull String instanceId) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().unregisterForActivityResults(instanceId);
         }
     }
 
     @Override
-    void requestPermissions(String instanceId, String[] permissions, int requestCode) {
+    void requestPermissions(@NonNull String instanceId, @NonNull String[] permissions, int requestCode) {
         if (hostController != null && hostController.getRouter() != null) {
             hostController.getRouter().requestPermissions(instanceId, permissions, requestCode);
         }
@@ -132,7 +151,7 @@ public class ControllerHostedRouter extends Router {
     }
 
     @Override
-    public void saveInstanceState(Bundle outState) {
+    public void saveInstanceState(@NonNull Bundle outState) {
         super.saveInstanceState(outState);
 
         outState.putInt(KEY_HOST_ID, hostId);
@@ -140,7 +159,7 @@ public class ControllerHostedRouter extends Router {
     }
 
     @Override
-    public void restoreInstanceState(Bundle savedInstanceState) {
+    public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
         super.restoreInstanceState(savedInstanceState);
 
         hostId = savedInstanceState.getInt(KEY_HOST_ID);
@@ -148,24 +167,34 @@ public class ControllerHostedRouter extends Router {
     }
 
     @Override
-    void setControllerRouter(Controller controller) {
+    void setControllerRouter(@NonNull Controller controller) {
         super.setControllerRouter(controller);
         controller.setParentController(hostController);
     }
 
-    public int getHostId() {
+    int getHostId() {
         return hostId;
     }
 
-    public String getTag() {
+    @Nullable
+    String getTag() {
         return tag;
     }
 
-    @Override
+    @Override @NonNull
     List<Router> getSiblingRouters() {
         List<Router> list = new ArrayList<>();
         list.addAll(hostController.getChildRouters());
         list.addAll(hostController.getRouter().getSiblingRouters());
         return list;
     }
+
+    @Override @NonNull
+    Router getRootRouter() {
+        if (hostController != null && hostController.getRouter() != null) {
+            return hostController.getRouter().getRootRouter();
+        } else {
+            return this;
+        }
+    }
 }

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

@@ -0,0 +1,53 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+/**
+ * A simple controller subclass that changes the onCreateView signature to include a saved view state parameter.
+ * This is necessary for some third party libraries like Google Maps, which require passing in a saved state
+ * bundle at the time of creation.
+ */
+abstract public class RestoreViewOnCreateController extends Controller {
+
+    /**
+     * Convenience constructor for use when no arguments are needed.
+     */
+    protected RestoreViewOnCreateController() {
+        super(null);
+    }
+
+    /**
+     * Constructor that takes arguments that need to be retained across restarts.
+     *
+     * @param args Any arguments that need to be retained.
+     */
+    protected RestoreViewOnCreateController(@Nullable Bundle args) {
+        super(args);
+    }
+
+    @Override @NonNull
+    protected final View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
+        return onCreateView(inflater, container, viewState);
+    }
+
+    /**
+     * Called when the controller is ready to display its view. A valid view must be returned. The standard body
+     * for this method will be {@code return inflater.inflate(R.layout.my_layout, container, false);}, plus
+     * any binding and state restoration code.
+     *
+     * @param inflater       The LayoutInflater that should be used to inflate views
+     * @param container      The parent view that this Controller's view will eventually be attached to.
+     *                       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.
+     */
+    @NonNull
+    protected abstract View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container, @Nullable Bundle savedViewState);
+
+}

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

@@ -4,6 +4,8 @@ import android.app.Activity;
 import android.content.Intent;
 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;
@@ -16,6 +18,7 @@ import com.bluelinelabs.conductor.changehandler.SimpleSwapChangeHandler;
 import com.bluelinelabs.conductor.internal.NoOpControllerChangeHandler;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
@@ -29,9 +32,10 @@ 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();
+    protected final Backstack backstack = new Backstack();
+    private OnControllerPushedListener onControllerPushedListener;
     private final List<ControllerChangeListener> changeListeners = new ArrayList<>();
-    private final List<Controller> destroyingControllers = new ArrayList<>();
+    final List<Controller> destroyingControllers = new ArrayList<>();
 
     private boolean popsLastView = false;
 
@@ -40,6 +44,7 @@ public abstract class Router {
     /**
      * Returns this Router's host Activity
      */
+    @Nullable
     public abstract Activity getActivity();
 
     /**
@@ -50,7 +55,7 @@ public abstract class Router {
      * @param resultCode The Activity's onActivityResult resultCode
      * @param data The Activity's onActivityResult data
      */
-    public abstract void onActivityResult(int requestCode, int resultCode, Intent data);
+    public abstract void onActivityResult(int requestCode, int resultCode, @Nullable Intent data);
 
     /**
      * This should be called by the host Activity when its onRequestPermissionsResult method is called. The call will be forwarded
@@ -61,7 +66,7 @@ public abstract class Router {
      * @param permissions The Activity's onRequestPermissionsResult permissions
      * @param grantResults The Activity's onRequestPermissionsResult grantResults
      */
-    public void onRequestPermissionsResult(String instanceId, int requestCode, String[] permissions, int[] grantResults) {
+    public void onRequestPermissionsResult(@NonNull String instanceId, int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         Controller controller = getControllerWithInstanceId(instanceId);
         if (controller != null) {
             controller.requestPermissionsResult(requestCode, permissions, grantResults);
@@ -71,10 +76,14 @@ public abstract class Router {
     /**
      * This should be called by the host Activity when its onBackPressed method is called. The call will be forwarded
      * to its top {@link Controller}. If that controller doesn't handle it, then it will be popped.
+     *
+     * @return Whether or not a back action was handled by the Router
      */
+    @UiThread
     public boolean handleBack() {
-        if (!backStack.isEmpty()) {
-            if (backStack.peek().controller.handleBack()) {
+        if (!backstack.isEmpty()) {
+            //noinspection ConstantConditions
+            if (backstack.peek().controller.handleBack()) {
                 return true;
             } else if (popCurrentController()) {
                 return true;
@@ -89,8 +98,13 @@ public abstract class Router {
      *
      * @return Whether or not this Router still has controllers remaining on it after popping.
      */
+    @UiThread
     public boolean popCurrentController() {
-        return popController(backStack.peek().controller);
+        RouterTransaction transaction = backstack.peek();
+        if (transaction == null) {
+            throw new IllegalStateException("Trying to pop the current controller when there are none on the backstack.");
+        }
+        return popController(transaction.controller);
     }
 
     /**
@@ -99,29 +113,30 @@ public abstract class Router {
      * @param controller The controller that should be popped from this Router
      * @return Whether or not this Router still has controllers remaining on it after popping.
      */
-    public boolean popController(Controller controller) {
-        RouterTransaction topController = backStack.peek();
+    @UiThread
+    public boolean popController(@NonNull Controller controller) {
+        RouterTransaction topController = backstack.peek();
         boolean poppingTopController = topController != null && topController.controller == controller;
 
         if (poppingTopController) {
-            trackDestroyingController(backStack.pop());
+            trackDestroyingController(backstack.pop());
         } else {
-            for (RouterTransaction transaction : backStack) {
+            for (RouterTransaction transaction : backstack) {
                 if (transaction.controller == controller) {
-                    backStack.remove(transaction);
+                    backstack.remove(transaction);
                     break;
                 }
             }
         }
 
         if (poppingTopController) {
-            performControllerChange(backStack.peek(), topController, false);
+            performControllerChange(backstack.peek(), topController, false);
         }
 
         if (popsLastView) {
             return topController != null;
         } else {
-            return !backStack.isEmpty();
+            return !backstack.isEmpty();
         }
     }
 
@@ -131,8 +146,9 @@ 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.
      */
+    @UiThread
     public void pushController(@NonNull RouterTransaction transaction) {
-        RouterTransaction from = backStack.peek();
+        RouterTransaction from = backstack.peek();
         pushToBackstack(transaction);
         performControllerChange(transaction, from, true);
     }
@@ -143,19 +159,35 @@ 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.
      */
+    @UiThread
     public void replaceTopController(@NonNull RouterTransaction transaction) {
-        RouterTransaction topTransaction = backStack.peek();
-        if (!backStack.isEmpty()) {
-            trackDestroyingController(backStack.pop());
+        RouterTransaction topTransaction = backstack.peek();
+        if (!backstack.isEmpty()) {
+            trackDestroyingController(backstack.pop());
+        }
+
+        final ControllerChangeHandler handler = transaction.pushChangeHandler();
+        if (topTransaction != null) {
+            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 != null ? handler.copy() : new SimpleSwapChangeHandler());
+                }
+            }
         }
 
         pushToBackstack(transaction);
-        performControllerChange(transaction, topTransaction, true);
+
+        if (handler != null) {
+            handler.setForceRemoveViewOnPush(true);
+        }
+        performControllerChange(transaction.pushChangeHandler(handler), topTransaction, true);
     }
 
     void destroy() {
         popsLastView = true;
-        List<RouterTransaction> poppedControllers = backStack.popAll();
+        List<RouterTransaction> poppedControllers = backstack.popAll();
 
         if (poppedControllers.size() > 0) {
             trackDestroyingControllers(poppedControllers);
@@ -164,11 +196,16 @@ public abstract class Router {
         }
     }
 
+    public int getContainerId() {
+        return container != null ? container.getId() : 0;
+    }
+
     /**
      * If set to true, this router will handle back presses by performing a change handler on the last controller and view
-     * in the stack. This defaults to false so that the developer can either finish its containing Activity or otherwise 
+     * in the stack. This defaults to false so that the developer can either finish its containing Activity or otherwise
      * hide its parent view without any strange artifacting.
      */
+    @NonNull
     public Router setPopsLastView(boolean popsLastView) {
         this.popsLastView = popsLastView;
         return this;
@@ -179,6 +216,7 @@ public abstract class Router {
      *
      * @return Whether or not any {@link Controller}s were popped in order to get to the root transaction
      */
+    @UiThread
     public boolean popToRoot() {
         return popToRoot(null);
     }
@@ -189,9 +227,11 @@ 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
      */
-    public boolean popToRoot(ControllerChangeHandler changeHandler) {
-        if (backStack.size() > 1) {
-            popToTransaction(backStack.root(), changeHandler);
+    @UiThread
+    public boolean popToRoot(@Nullable ControllerChangeHandler changeHandler) {
+        if (backstack.size() > 1) {
+            //noinspection ConstantConditions
+            popToTransaction(backstack.root(), changeHandler);
             return true;
         } else {
             return false;
@@ -204,6 +244,7 @@ public abstract class Router {
      * @param tag The tag being popped to
      * @return Whether or not any {@link Controller}s were popped in order to get to the transaction with the passed tag
      */
+    @UiThread
     public boolean popToTag(@NonNull String tag) {
         return popToTag(tag, null);
     }
@@ -215,8 +256,9 @@ public abstract class Router {
      * @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
      */
-    public boolean popToTag(@NonNull String tag, ControllerChangeHandler changeHandler) {
-        for (RouterTransaction transaction : backStack) {
+    @UiThread
+    public boolean popToTag(@NonNull String tag, @Nullable ControllerChangeHandler changeHandler) {
+        for (RouterTransaction transaction : backstack) {
             if (tag.equals(transaction.tag())) {
                 popToTransaction(transaction, changeHandler);
                 return true;
@@ -231,14 +273,31 @@ 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.
      */
+    @UiThread
     public void setRoot(@NonNull RouterTransaction transaction) {
-        RouterTransaction currentTop = backStack.peek();
-        removeAllExceptTopAndUnowned();
+        ControllerChangeHandler newHandler = transaction.pushChangeHandler() != null ? transaction.pushChangeHandler() : new SimpleSwapChangeHandler();
 
-        trackDestroyingControllers(backStack.popAll());
+        List<RouterTransaction> visibleTransactions = getVisibleTransactions(backstack.iterator());
+        RouterTransaction rootTransaction = visibleTransactions.size() > 0 ? visibleTransactions.get(0) : null;
+
+        removeAllExceptVisibleAndUnowned();
+
+        trackDestroyingControllers(backstack.popAll());
 
         pushToBackstack(transaction);
-        performControllerChange(transaction, currentTop, true);
+
+        for (int i = visibleTransactions.size() - 1; i > 0; i--) {
+            if (visibleTransactions.get(i).controller.getView() == null) {
+                ControllerChangeHandler.abortPush(visibleTransactions.get(i).controller, transaction.controller, newHandler);
+            } else {
+                performControllerChange(null, visibleTransactions.get(i).controller, true, newHandler);
+            }
+        }
+
+        if (rootTransaction != null && rootTransaction.controller.getView() == null) {
+            ControllerChangeHandler.abortPush(rootTransaction.controller, transaction.controller, newHandler);
+        }
+        performControllerChange(transaction, rootTransaction, true);
     }
 
     /**
@@ -247,8 +306,9 @@ public abstract class Router {
      * @param instanceId The instance ID being searched for
      * @return The matching Controller, if one exists
      */
-    public Controller getControllerWithInstanceId(String instanceId) {
-        for (RouterTransaction transaction : backStack) {
+    @Nullable
+    public Controller getControllerWithInstanceId(@NonNull String instanceId) {
+        for (RouterTransaction transaction : backstack) {
             Controller controllerWithId = transaction.controller.findController(instanceId);
             if (controllerWithId != null) {
                 return controllerWithId;
@@ -263,8 +323,9 @@ public abstract class Router {
      * @param tag The tag being searched for
      * @return The matching Controller, if one exists
      */
-    public Controller getControllerWithTag(String tag) {
-        for (RouterTransaction transaction : backStack) {
+    @Nullable
+    public Controller getControllerWithTag(@NonNull String tag) {
+        for (RouterTransaction transaction : backstack) {
             if (tag.equals(transaction.tag())) {
                 return transaction.controller;
             }
@@ -276,15 +337,16 @@ public abstract class Router {
      * Returns the number of {@link Controller}s currently in the backstack
      */
     public int getBackstackSize() {
-        return backStack.size();
+        return backstack.size();
     }
 
     /**
      * Returns the current backstack, ordered from root to most recently pushed.
      */
+    @NonNull
     public List<RouterTransaction> getBackstack() {
         List<RouterTransaction> list = new ArrayList<>();
-        Iterator<RouterTransaction> backstackIterator = backStack.reverseIterator();
+        Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             list.add(backstackIterator.next());
         }
@@ -295,20 +357,48 @@ 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 backstack The new backstack
-     * @param changeHandler An optional change handler to be used to handle the transition
+     * @param newBackstack The new backstack
+     * @param changeHandler An optional change handler to be used to handle the root view of transition
      */
-    public void setBackstack(@NonNull List<RouterTransaction> backstack, ControllerChangeHandler changeHandler) {
-        RouterTransaction oldTopTransaction = backStack.peek();
-        Controller oldTop = oldTopTransaction != null ? oldTopTransaction.controller : null;
-        removeAllExceptTopAndUnowned();
+    @UiThread
+    public void setBackstack(@NonNull List<RouterTransaction> newBackstack, @Nullable ControllerChangeHandler changeHandler) {
+        List<RouterTransaction> oldVisibleTransactions = getVisibleTransactions(backstack.iterator());
 
-        if (backstack.size() > 0) {
-            Controller newTop = backstack.get(backstack.size() - 1).controller;
+        removeAllExceptVisibleAndUnowned();
 
-            if (newTop != oldTop) {
+        if (newBackstack.size() > 0) {
+            List<RouterTransaction> reverseNewBackstack = new ArrayList<>(newBackstack);
+            Collections.reverse(reverseNewBackstack);
+            List<RouterTransaction> newVisibleTransactions = getVisibleTransactions(reverseNewBackstack.iterator());
+
+            boolean visibleTransactionsChanged = newVisibleTransactions.size() != oldVisibleTransactions.size();
+            if (!visibleTransactionsChanged) {
+                for (int i = 0; i < oldVisibleTransactions.size(); i++) {
+                    if (oldVisibleTransactions.get(i).controller != newVisibleTransactions.get(i).controller) {
+                        visibleTransactionsChanged = true;
+                        break;
+                    }
+                }
+            }
+
+            if (visibleTransactionsChanged) {
                 ControllerChangeHandler handler = changeHandler != null ? changeHandler : new SimpleSwapChangeHandler();
-                performControllerChange(newTop, oldTop, true, handler);
+
+                Controller rootController = oldVisibleTransactions.size() > 0 ? oldVisibleTransactions.get(0).controller : null;
+                performControllerChange(newVisibleTransactions.get(0).controller, rootController, true, handler.copy());
+
+                for (int i = oldVisibleTransactions.size() - 1; i > 0; i--) {
+                    RouterTransaction transaction = oldVisibleTransactions.get(i);
+                    ControllerChangeHandler localHandler = handler.copy();
+                    localHandler.setForceRemoveViewOnPush(true);
+                    performControllerChange(null, transaction.controller, true, localHandler);
+                }
+
+                for (int i = 1; i < newVisibleTransactions.size(); i++) {
+                    RouterTransaction transaction = newVisibleTransactions.get(i);
+                    handler = transaction.pushChangeHandler() != null ? transaction.pushChangeHandler().copy() : new SimpleSwapChangeHandler();
+                    performControllerChange(transaction.controller, newVisibleTransactions.get(i - 1).controller, true, handler);
+                }
             }
         }
 
@@ -316,7 +406,13 @@ public abstract class Router {
             transaction.onAttachedToRouter();
         }
 
-        backStack.setBackstack(backstack);
+        backstack.setBackstack(newBackstack);
+
+        if (onControllerPushedListener != null) {
+            for (RouterTransaction transaction : newBackstack) {
+                onControllerPushedListener.onControllerPushed(transaction.controller);
+            }
+        }
     }
 
     /**
@@ -331,7 +427,7 @@ public abstract class Router {
      *
      * @param changeListener The listener
      */
-    public void addChangeListener(ControllerChangeListener changeListener) {
+    public void addChangeListener(@NonNull ControllerChangeListener changeListener) {
         if (!changeListeners.contains(changeListener)) {
             changeListeners.add(changeListener);
         }
@@ -342,15 +438,16 @@ public abstract class Router {
      *
      * @param changeListener The listener to be removed
      */
-    public void removeChangeListener(ControllerChangeListener changeListener) {
+    public void removeChangeListener(@NonNull ControllerChangeListener changeListener) {
         changeListeners.remove(changeListener);
     }
 
     /**
      * Attaches this Router's existing backstack to its container if one exists.
      */
+    @UiThread
     public void rebindIfNeeded() {
-        Iterator<RouterTransaction> backstackIterator = backStack.reverseIterator();
+        Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             RouterTransaction transaction = backstackIterator.next();
 
@@ -360,15 +457,15 @@ public abstract class Router {
         }
     }
 
-    public final void onActivityResult(String instanceId, int requestCode, int resultCode, Intent data) {
+    public final void onActivityResult(@NonNull String instanceId, int requestCode, int resultCode, @Nullable Intent data) {
         Controller controller = getControllerWithInstanceId(instanceId);
         if (controller != null) {
             controller.onActivityResult(requestCode, resultCode, data);
         }
     }
 
-    public final void onActivityStarted(Activity activity) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onActivityStarted(@NonNull Activity activity) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.activityStarted(activity);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -377,8 +474,8 @@ public abstract class Router {
         }
     }
 
-    public final void onActivityResumed(Activity activity) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onActivityResumed(@NonNull Activity activity) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.activityResumed(activity);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -387,8 +484,8 @@ public abstract class Router {
         }
     }
 
-    public final void onActivityPaused(Activity activity) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onActivityPaused(@NonNull Activity activity) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.activityPaused(activity);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -397,8 +494,8 @@ public abstract class Router {
         }
     }
 
-    public final void onActivityStopped(Activity activity) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onActivityStopped(@NonNull Activity activity) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.activityStopped(activity);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -407,11 +504,11 @@ public abstract class Router {
         }
     }
 
-    public void onActivityDestroyed(Activity activity) {
+    public void onActivityDestroyed(@NonNull Activity activity) {
         prepareForContainerRemoval();
         changeListeners.clear();
 
-        for (RouterTransaction transaction : backStack) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.activityDestroyed(activity.isChangingConfigurations());
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -432,34 +529,37 @@ public abstract class Router {
     }
 
     public void prepareForHostDetach() {
-        for (RouterTransaction transaction : backStack) {
+        for (RouterTransaction transaction : backstack) {
+            if (ControllerChangeHandler.completePushImmediately(transaction.controller.getInstanceId())) {
+                transaction.controller.setNeedsAttach();
+            }
             transaction.controller.prepareForHostDetach();
         }
     }
 
-    public void saveInstanceState(Bundle outState) {
+    public void saveInstanceState(@NonNull Bundle outState) {
         prepareForHostDetach();
 
         Bundle backstackState = new Bundle();
-        backStack.saveInstanceState(backstackState);
+        backstack.saveInstanceState(backstackState);
 
         outState.putParcelable(KEY_BACKSTACK, backstackState);
         outState.putBoolean(KEY_POPS_LAST_VIEW, popsLastView);
     }
 
-    public void restoreInstanceState(Bundle savedInstanceState) {
+    public void restoreInstanceState(@NonNull Bundle savedInstanceState) {
         Bundle backstackBundle = savedInstanceState.getParcelable(KEY_BACKSTACK);
-        backStack.restoreInstanceState(backstackBundle);
+        backstack.restoreInstanceState(backstackBundle);
         popsLastView = savedInstanceState.getBoolean(KEY_POPS_LAST_VIEW);
 
-        Iterator<RouterTransaction> backstackIterator = backStack.reverseIterator();
+        Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             setControllerRouter(backstackIterator.next().controller);
         }
     }
 
-    public final void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.createOptionsMenu(menu, inflater);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -468,8 +568,8 @@ public abstract class Router {
         }
     }
 
-    public final void onPrepareOptionsMenu(Menu menu) {
-        for (RouterTransaction transaction : backStack) {
+    public final void onPrepareOptionsMenu(@NonNull Menu menu) {
+        for (RouterTransaction transaction : backstack) {
             transaction.controller.prepareOptionsMenu(menu);
 
             for (Router childRouter : transaction.controller.getChildRouters()) {
@@ -478,8 +578,8 @@ public abstract class Router {
         }
     }
 
-    public final boolean onOptionsItemSelected(MenuItem item) {
-        for (RouterTransaction transaction : backStack) {
+    public final boolean onOptionsItemSelected(@NonNull MenuItem item) {
+        for (RouterTransaction transaction : backstack) {
             if (transaction.controller.optionsItemSelected(item)) {
                 return true;
             }
@@ -493,9 +593,9 @@ public abstract class Router {
         return false;
     }
 
-    private void popToTransaction(@NonNull RouterTransaction transaction, ControllerChangeHandler changeHandler) {
-        RouterTransaction topTransaction = backStack.peek();
-        List<RouterTransaction> poppedTransactions = backStack.popTo(transaction);
+    private void popToTransaction(@NonNull RouterTransaction transaction, @Nullable ControllerChangeHandler changeHandler) {
+        RouterTransaction topTransaction = backstack.peek();
+        List<RouterTransaction> poppedTransactions = backstack.popTo(transaction);
         trackDestroyingControllers(poppedTransactions);
 
         if (poppedTransactions.size() > 0) {
@@ -503,20 +603,25 @@ public abstract class Router {
                 changeHandler = topTransaction.popChangeHandler();
             }
 
-            performControllerChange(backStack.peek().controller, topTransaction.controller, false, changeHandler);
+            performControllerChange(backstack.peek().controller, topTransaction.controller, false, changeHandler);
         }
     }
 
+    final void setOnControllerPushedListener(OnControllerPushedListener listener) {
+        onControllerPushedListener = listener;
+    }
+
     void prepareForContainerRemoval() {
         if (container != null) {
             container.setOnHierarchyChangeListener(null);
         }
     }
 
+    @NonNull
     final List<Controller> getControllers() {
         List<Controller> controllers = new ArrayList<>();
 
-        Iterator<RouterTransaction> backstackIterator = backStack.reverseIterator();
+        Iterator<RouterTransaction> backstackIterator = backstack.reverseIterator();
         while (backstackIterator.hasNext()) {
             controllers.add(backstackIterator.next().controller);
         }
@@ -524,8 +629,9 @@ public abstract class Router {
         return controllers;
     }
 
+    @Nullable
     public final Boolean handleRequestedPermission(@NonNull String permission) {
-        for (RouterTransaction transaction : backStack) {
+        for (RouterTransaction transaction : backstack) {
             if (transaction.controller.didRequestPermission(permission)) {
                 return transaction.controller.shouldShowRequestPermissionRationale(permission);
             }
@@ -533,7 +639,7 @@ public abstract class Router {
         return null;
     }
 
-    private void performControllerChange(RouterTransaction to, RouterTransaction from, boolean isPush) {
+    private void performControllerChange(@Nullable RouterTransaction to, @Nullable RouterTransaction from, boolean isPush) {
         if (isPush && to != null) {
             to.onAttachedToRouter();
         }
@@ -554,10 +660,10 @@ public abstract class Router {
         performControllerChange(toController, fromController, isPush, changeHandler);
     }
 
-    private void performControllerChange(final Controller to, final Controller from, boolean isPush, @NonNull ControllerChangeHandler changeHandler) {
+    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) {
+        } 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();
@@ -566,11 +672,15 @@ public abstract class Router {
         ControllerChangeHandler.executeChange(to, from, isPush, container, changeHandler, changeListeners);
     }
 
-    void pushToBackstack(@NonNull RouterTransaction entry) {
-        backStack.push(entry);
+    private void pushToBackstack(@NonNull RouterTransaction entry) {
+        backstack.push(entry);
+
+        if (onControllerPushedListener != null) {
+            onControllerPushedListener.onControllerPushed(entry.controller);
+        }
     }
 
-    private void trackDestroyingController(RouterTransaction transaction) {
+    private void trackDestroyingController(@NonNull RouterTransaction transaction) {
         if (!transaction.controller.isDestroyed()) {
             destroyingControllers.add(transaction.controller);
 
@@ -583,19 +693,19 @@ public abstract class Router {
         }
     }
 
-    private void trackDestroyingControllers(List<RouterTransaction> transactions) {
+    private void trackDestroyingControllers(@NonNull List<RouterTransaction> transactions) {
         for (RouterTransaction transaction : transactions) {
             trackDestroyingController(transaction);
         }
     }
 
-    private void removeAllExceptTopAndUnowned() {
+    private void removeAllExceptVisibleAndUnowned() {
         List<View> views = new ArrayList<>();
 
-        RouterTransaction topTransaction = backStack.peek();
-        final View topView = topTransaction != null ? topTransaction.controller.getView() : null;
-        if (topView != null) {
-            views.add(topView);
+        for (RouterTransaction transaction : getVisibleTransactions(backstack.iterator())) {
+            if (transaction.controller.getView() != null) {
+                views.add(transaction.controller.getView());
+            }
         }
 
         for (Router router : getSiblingRouters()) {
@@ -613,7 +723,7 @@ public abstract class Router {
         }
     }
 
-    private void addRouterViewsToList(Router router, List<View> list) {
+    private void addRouterViewsToList(@NonNull Router router, @NonNull List<View> list) {
         for (Controller controller : router.getControllers()) {
             if (controller.getView() != null) {
                 list.add(controller.getView());
@@ -625,17 +735,37 @@ public abstract class Router {
         }
     }
 
-    void setControllerRouter(Controller controller) {
+    private List<RouterTransaction> getVisibleTransactions(@NonNull Iterator<RouterTransaction> backstackIterator) {
+        List<RouterTransaction> transactions = new ArrayList<>();
+        while (backstackIterator.hasNext()) {
+            RouterTransaction transaction = backstackIterator.next();
+            transactions.add(transaction);
+
+            if (transaction.pushChangeHandler() == null || transaction.pushChangeHandler().removesFromViewOnPush()) {
+                break;
+            }
+        }
+
+        Collections.reverse(transactions);
+        return transactions;
+    }
+
+    void setControllerRouter(@NonNull Controller controller) {
         controller.setRouter(this);
     }
 
     abstract void invalidateOptionsMenu();
-    abstract void startActivity(Intent intent);
-    abstract void startActivityForResult(String instanceId, Intent intent, int requestCode);
-    abstract void startActivityForResult(String instanceId, Intent intent, int requestCode, Bundle options);
-    abstract void registerForActivityResult(String instanceId, int requestCode);
-    abstract void unregisterForActivityResults(String instanceId);
-    abstract void requestPermissions(String instanceId, String[] permissions, int requestCode);
+    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 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();
-    abstract List<Router> getSiblingRouters();
+    @NonNull abstract List<Router> getSiblingRouters();
+    @NonNull abstract Router getRootRouter();
+
+    interface OnControllerPushedListener {
+        void onControllerPushed(Controller controller);
+    }
 }

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

@@ -2,6 +2,7 @@ package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
 /**
  * Metadata used for adding {@link Controller}s to a {@link Router}.
@@ -21,6 +22,7 @@ public class RouterTransaction {
     private ControllerChangeHandler popControllerChangeHandler;
     private boolean attachedToRouter;
 
+    @NonNull
     public static RouterTransaction with(@NonNull Controller controller) {
         return new RouterTransaction(controller);
     }
@@ -41,15 +43,18 @@ public class RouterTransaction {
         attachedToRouter = true;
     }
 
+    @NonNull
     public Controller controller() {
         return controller;
     }
 
+    @Nullable
     public String tag() {
         return tag;
     }
 
-    public RouterTransaction tag(String tag) {
+    @NonNull
+    public RouterTransaction tag(@Nullable String tag) {
         if (!attachedToRouter) {
             this.tag = tag;
             return this;
@@ -58,6 +63,7 @@ public class RouterTransaction {
         }
     }
 
+    @Nullable
     public ControllerChangeHandler pushChangeHandler() {
         ControllerChangeHandler handler = controller.getOverriddenPushHandler();
         if (handler == null) {
@@ -66,7 +72,8 @@ public class RouterTransaction {
         return handler;
     }
 
-    public RouterTransaction pushChangeHandler(ControllerChangeHandler handler) {
+    @NonNull
+    public RouterTransaction pushChangeHandler(@Nullable ControllerChangeHandler handler) {
         if (!attachedToRouter) {
             pushControllerChangeHandler = handler;
             return this;
@@ -75,6 +82,7 @@ public class RouterTransaction {
         }
     }
 
+    @Nullable
     public ControllerChangeHandler popChangeHandler() {
         ControllerChangeHandler handler = controller.getOverriddenPopHandler();
         if (handler == null) {
@@ -83,7 +91,8 @@ public class RouterTransaction {
         return handler;
     }
 
-    public RouterTransaction popChangeHandler(ControllerChangeHandler handler) {
+    @NonNull
+    public RouterTransaction popChangeHandler(@Nullable ControllerChangeHandler handler) {
         if (!attachedToRouter) {
             popControllerChangeHandler = handler;
             return this;
@@ -95,6 +104,7 @@ public class RouterTransaction {
     /**
      * Used to serialize this transaction into a Bundle
      */
+    @NonNull
     public Bundle saveInstanceState() {
         Bundle bundle = new Bundle();
 

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

@@ -1,9 +1,11 @@
 package com.bluelinelabs.conductor.changehandler;
 
 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 android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewTreeObserver;
@@ -24,6 +26,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
     private long animationDuration;
     private boolean removesFromViewOnPush;
     private boolean canceled;
+    private boolean needsImmediateCompletion;
+    private boolean completed;
     private Animator animator;
 
     public AnimatorChangeHandler() {
@@ -58,7 +62,7 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
     }
 
     @Override
-    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, Controller newTop) {
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
         super.onAbortPush(newHandler, newTop);
 
         canceled = true;
@@ -67,10 +71,21 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         }
     }
 
+    @Override
+    public void completeImmediately() {
+        super.completeImmediately();
+
+        needsImmediateCompletion = true;
+        if (animator != null) {
+            animator.end();
+        }
+    }
+
     public long getAnimationDuration() {
         return animationDuration;
     }
 
+    @Override
     public boolean removesFromViewOnPush() {
         return removesFromViewOnPush;
     }
@@ -84,7 +99,8 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
      * @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.
      */
-    protected abstract Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer);
+    @NonNull
+    protected abstract Animator getAnimator(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, boolean toAddedToContainer);
 
     /**
      * Will be called after the animation is complete to reset the View that was removed to its pre-animation state.
@@ -92,14 +108,14 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
     protected abstract void resetFromView(@NonNull View from);
 
     @Override
-    public final void performChange(@NonNull final ViewGroup container, final View from, final View to, final boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
+    public final void performChange(@NonNull final ViewGroup container, @Nullable final View from, @Nullable final View to, final boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
         boolean readyToAnimate = true;
         final boolean addingToView = to != null && to.getParent() == null;
 
         if (addingToView) {
             if (isPush || from == null) {
                 container.addView(to);
-            } else {
+            } else if (to.getParent() == null) {
                 container.addView(to, container.indexOfChild(from));
             }
 
@@ -124,9 +140,23 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         }
     }
 
-    private void performAnimation(@NonNull final ViewGroup container, final View from, View to, final boolean isPush, final boolean toAddedToContainer, @NonNull final ControllerChangeCompletedListener changeListener) {
-        if (canceled) {
+    private void complete(@NonNull ControllerChangeCompletedListener changeListener, @Nullable AnimatorListener animatorListener) {
+        if (!completed) {
+            completed = true;
             changeListener.onChangeCompleted();
+        }
+
+        if (animator != null) {
+            if (animatorListener != null) {
+                animator.removeListener(animatorListener);
+            }
+            animator = 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) {
+        if (canceled) {
+            complete(changeListener, null);
             return;
         }
 
@@ -139,22 +169,29 @@ public abstract class AnimatorChangeHandler extends ControllerChangeHandler {
         animator.addListener(new AnimatorListenerAdapter() {
             @Override
             public void onAnimationCancel(Animator animation) {
-                changeListener.onChangeCompleted();
+                if (from != null && (!isPush || removesFromViewOnPush) && needsImmediateCompletion) {
+                    container.removeView(from);
+                }
+
+                complete(changeListener, this);
             }
 
             @Override
             public void onAnimationEnd(Animator animation) {
-                if (from != null && (!isPush || removesFromViewOnPush)) {
-                    container.removeView(from);
-                }
+                if (!canceled && animator != null) {
+                    if (from != null && (!isPush || removesFromViewOnPush)) {
+                        container.removeView(from);
+                    }
 
-                changeListener.onChangeCompleted();
+                    complete(changeListener, this);
 
-                if (isPush && from != null) {
-                    resetFromView(from);
+                    if (isPush && from != null) {
+                        resetFromView(from);
+                    }
                 }
             }
         });
+
         animator.start();
     }
 

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

@@ -3,6 +3,7 @@ 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;
@@ -14,9 +15,8 @@ import android.view.ViewGroup;
 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
 public class AutoTransitionChangeHandler extends TransitionChangeHandler {
 
-    @Override
-    @NonNull
-    protected Transition getTransition(@NonNull ViewGroup container, View from, View to, boolean isPush) {
+    @Override @NonNull
+    protected Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush) {
         return new AutoTransition();
     }
 

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

@@ -4,6 +4,7 @@ import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -26,8 +27,8 @@ public class FadeChangeHandler extends AnimatorChangeHandler {
         super(duration, removesFromViewOnPush);
     }
 
-    @Override
-    protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
+    @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));

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

@@ -4,6 +4,7 @@ import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -26,8 +27,8 @@ public class HorizontalChangeHandler extends AnimatorChangeHandler {
         super(duration, removesFromViewOnPush);
     }
 
-    @Override
-    protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
+    @Override @NonNull
+    protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, boolean toAddedToContainer) {
         AnimatorSet animatorSet = new AnimatorSet();
 
         if (isPush) {

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

@@ -2,20 +2,28 @@ package com.bluelinelabs.conductor.changehandler;
 
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
+import android.view.View.OnAttachStateChangeListener;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.Controller;
 import com.bluelinelabs.conductor.ControllerChangeHandler;
 
 /**
  * A {@link ControllerChangeHandler} that will instantly swap Views with no animations or transitions.
  */
-public class SimpleSwapChangeHandler extends ControllerChangeHandler {
+public class SimpleSwapChangeHandler extends ControllerChangeHandler implements OnAttachStateChangeListener {
 
     private static final String KEY_REMOVES_FROM_ON_PUSH = "SimpleSwapChangeHandler.removesFromViewOnPush";
 
     private boolean removesFromViewOnPush;
 
+    private boolean canceled;
+
+    private ViewGroup container;
+    private ControllerChangeCompletedListener changeListener;
+
     public SimpleSwapChangeHandler() {
         this(true);
     }
@@ -37,16 +45,61 @@ public class SimpleSwapChangeHandler extends ControllerChangeHandler {
     }
 
     @Override
-    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
-        if (from != null && (!isPush || removesFromViewOnPush)) {
-            container.removeView(from);
-        }
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
+        super.onAbortPush(newHandler, newTop);
 
-        if (to != null && to.getParent() == null) {
-            container.addView(to);
-        }
-
-        changeListener.onChangeCompleted();
+        canceled = true;
     }
 
-}
+    @Override
+    public void completeImmediately() {
+        if (changeListener != null) {
+            changeListener.onChangeCompleted();
+            changeListener = null;
+
+            container.removeOnAttachStateChangeListener(this);
+            container = null;
+        }
+    }
+
+    @Override
+    public void performChange(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+        if (!canceled) {
+            if (from != null && (!isPush || removesFromViewOnPush)) {
+                container.removeView(from);
+            }
+
+            if (to != null && to.getParent() == null) {
+                container.addView(to);
+            }
+        }
+
+        if (container.getWindowToken() != null) {
+            changeListener.onChangeCompleted();
+        } else {
+            this.changeListener = changeListener;
+            this.container = container;
+            container.addOnAttachStateChangeListener(this);
+        }
+
+    }
+
+    @Override
+    public boolean removesFromViewOnPush() {
+        return removesFromViewOnPush;
+    }
+
+    @Override
+    public void onViewAttachedToWindow(@NonNull View v) {
+        v.removeOnAttachStateChangeListener(this);
+
+        if (changeListener != null) {
+            changeListener.onChangeCompleted();
+            changeListener = null;
+            container = null;
+        }
+    }
+
+    @Override
+    public void onViewDetachedFromWindow(@NonNull View v) { }
+}

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

@@ -3,6 +3,7 @@ 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.Transition;
 import android.transition.Transition.TransitionListener;
 import android.transition.TransitionManager;
@@ -29,17 +30,17 @@ public abstract class TransitionChangeHandler extends ControllerChangeHandler {
      * @param isPush True if this is a push transaction, false if it's a pop.
      */
     @NonNull
-    protected abstract Transition getTransition(@NonNull ViewGroup container, View from, View to, boolean isPush);
+    protected abstract Transition getTransition(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush);
 
     @Override
-    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, Controller newTop) {
+    public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable Controller newTop) {
         super.onAbortPush(newHandler, newTop);
 
         canceled = true;
     }
 
     @Override
-    public void performChange(@NonNull final ViewGroup container, View from, View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
+    public void performChange(@NonNull final ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
         if (canceled) {
             changeListener.onChangeCompleted();
             return;
@@ -71,9 +72,13 @@ public abstract class TransitionChangeHandler extends ControllerChangeHandler {
         if (from != null) {
             container.removeView(from);
         }
-        if (to != null) {
+        if (to != null && to.getParent() == null) {
             container.addView(to);
         }
     }
 
+    @Override
+    public final boolean removesFromViewOnPush() {
+        return true;
+    }
 }

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

@@ -3,6 +3,7 @@ package com.bluelinelabs.conductor.changehandler;
 import android.os.Build;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -15,13 +16,10 @@ import com.bluelinelabs.conductor.internal.ClassUtils;
  */
 public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
 
-    private static final String KEY_TRANSITION_HANDLER_CLASS = "TransitionChangeHandlerCompat.transitionChangeHandler.class";
-    private static final String KEY_FALLBACK_HANDLER_CLASS = "TransitionChangeHandlerCompat.fallbackChangeHandler.class";
-    private static final String KEY_TRANSITION_HANDLER_STATE = "TransitionChangeHandlerCompat.transitionChangeHandler.state";
-    private static final String KEY_FALLBACK_HANDLER_STATE = "TransitionChangeHandlerCompat.fallbackChangeHandler.state";
+    private static final String KEY_CHANGE_HANDLER_CLASS = "TransitionChangeHandlerCompat.changeHandler.class";
+    private static final String KEY_HANDLER_STATE = "TransitionChangeHandlerCompat.changeHandler.state";
 
-    private TransitionChangeHandler transitionChangeHandler;
-    private ControllerChangeHandler fallbackChangeHandler;
+    private ControllerChangeHandler changeHandler;
 
     public TransitionChangeHandlerCompat() { }
 
@@ -32,49 +30,43 @@ public class TransitionChangeHandlerCompat extends ControllerChangeHandler {
      * @param transitionChangeHandler The change handler that will be used on API 21 and above
      * @param fallbackChangeHandler The change handler that will be used on APIs below 21
      */
-    public TransitionChangeHandlerCompat(TransitionChangeHandler transitionChangeHandler, ControllerChangeHandler fallbackChangeHandler) {
-        this.transitionChangeHandler = transitionChangeHandler;
-        this.fallbackChangeHandler = fallbackChangeHandler;
+    public TransitionChangeHandlerCompat(@NonNull TransitionChangeHandler transitionChangeHandler, @NonNull ControllerChangeHandler fallbackChangeHandler) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            changeHandler = transitionChangeHandler;
+        } else {
+            changeHandler = fallbackChangeHandler;
+        }
     }
 
     @Override
-    public void performChange(@NonNull final ViewGroup container, View from, View to, boolean isPush, @NonNull final ControllerChangeCompletedListener changeListener) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
-            transitionChangeHandler.performChange(container, from, to, isPush, changeListener);
-        } else {
-            fallbackChangeHandler.performChange(container, from, to, isPush, changeListener);
-        }
+    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);
     }
 
     @Override
     public void saveToBundle(@NonNull Bundle bundle) {
         super.saveToBundle(bundle);
 
-        bundle.putString(KEY_TRANSITION_HANDLER_CLASS, transitionChangeHandler.getClass().getName());
-        bundle.putString(KEY_FALLBACK_HANDLER_CLASS, fallbackChangeHandler.getClass().getName());
+        bundle.putString(KEY_CHANGE_HANDLER_CLASS, changeHandler.getClass().getName());
 
-        Bundle transitionBundle = new Bundle();
-        transitionChangeHandler.saveToBundle(transitionBundle);
-        bundle.putBundle(KEY_TRANSITION_HANDLER_STATE, transitionBundle);
-
-        Bundle fallbackBundle = new Bundle();
-        fallbackChangeHandler.saveToBundle(fallbackBundle);
-        bundle.putBundle(KEY_FALLBACK_HANDLER_STATE, fallbackBundle);
+        Bundle stateBundle = new Bundle();
+        changeHandler.saveToBundle(stateBundle);
+        bundle.putBundle(KEY_HANDLER_STATE, stateBundle);
     }
 
     @Override
     public void restoreFromBundle(@NonNull Bundle bundle) {
         super.restoreFromBundle(bundle);
 
-        String transitionClassName = bundle.getString(KEY_TRANSITION_HANDLER_CLASS);
-        transitionChangeHandler = ClassUtils.newInstance(transitionClassName);
+        String className = bundle.getString(KEY_CHANGE_HANDLER_CLASS);
+        changeHandler = ClassUtils.newInstance(className);
         //noinspection ConstantConditions
-        transitionChangeHandler.restoreFromBundle(bundle.getBundle(KEY_TRANSITION_HANDLER_STATE));
+        changeHandler.restoreFromBundle(bundle.getBundle(KEY_HANDLER_STATE));
+    }
 
-        String fallbackClassName = bundle.getString(KEY_FALLBACK_HANDLER_CLASS);
-        fallbackChangeHandler = ClassUtils.newInstance(fallbackClassName);
-        //noinspection ConstantConditions
-        fallbackChangeHandler.restoreFromBundle(bundle.getBundle(KEY_FALLBACK_HANDLER_STATE));
+    @Override
+    public boolean removesFromViewOnPush() {
+        return changeHandler.removesFromViewOnPush();
     }
 
 }

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

@@ -4,6 +4,7 @@ import android.animation.Animator;
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -30,8 +31,8 @@ public class VerticalChangeHandler extends AnimatorChangeHandler {
         super(duration, removesFromViewOnPush);
     }
 
-    @Override
-    protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
+    @Override @NonNull
+    protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, boolean toAddedToContainer) {
         AnimatorSet animator = new AnimatorSet();
         List<Animator> viewAnimators = new ArrayList<>();
 

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

@@ -1,16 +1,13 @@
 package com.bluelinelabs.conductor.internal;
 
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.text.TextUtils;
 
 public class ClassUtils {
 
-    @SuppressWarnings("unchecked")
-    public static <T> Class<? extends T> classForName(String className) {
-        return classForName(className, true);
-    }
-
-    @SuppressWarnings("unchecked")
-    public static <T> Class<? extends T> classForName(String className, boolean allowEmptyName) {
+    @Nullable @SuppressWarnings("unchecked")
+    public static <T> Class<? extends T> classForName(@NonNull String className, boolean allowEmptyName) {
         if (allowEmptyName && TextUtils.isEmpty(className)) {
             return null;
         }
@@ -22,10 +19,10 @@ public class ClassUtils {
         }
     }
 
-    @SuppressWarnings("unchecked")
-    public static <T> T newInstance(String className) {
+    @Nullable @SuppressWarnings("unchecked")
+    public static <T> T newInstance(@NonNull String className) {
         try {
-            Class<? extends T> cls = classForName(className);
+            Class<? extends T> cls = classForName(className, true);
             return cls != null ? cls.newInstance() : null;
         } catch (Exception e) {
             throw new RuntimeException("An exception occurred while creating a new instance of " + className + ". " + e.getMessage());

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

@@ -8,7 +8,10 @@ import android.content.Context;
 import android.content.Intent;
 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;
@@ -27,15 +30,19 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
     private static final String FRAGMENT_TAG = "LifecycleHandler";
 
+    private static final String KEY_PENDING_PERMISSION_REQUESTS = "LifecycleHandler.pendingPermissionRequests";
     private static final String KEY_PERMISSION_REQUEST_CODES = "LifecycleHandler.permissionRequests";
     private static final String KEY_ACTIVITY_REQUEST_CODES = "LifecycleHandler.activityRequests";
+    private static final String KEY_ROUTER_STATE_PREFIX = "LifecycleHandler.routerState";
 
     private Activity activity;
     private boolean hasRegisteredCallbacks;
     private boolean destroyed;
+    private boolean attached;
 
     private SparseArray<String> permissionRequestMap = new SparseArray<>();
     private SparseArray<String> activityRequestMap = new SparseArray<>();
+    private ArrayList<PendingPermissionRequest> pendingPermissionRequests = new ArrayList<>();
 
     private final Map<Integer, ActivityHostedRouter> routerMap = new HashMap<>();
 
@@ -44,7 +51,8 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         setHasOptionsMenu(true);
     }
 
-    private static LifecycleHandler findInActivity(Activity activity) {
+    @Nullable
+    private static LifecycleHandler findInActivity(@NonNull Activity activity) {
         LifecycleHandler lifecycleHandler = (LifecycleHandler)activity.getFragmentManager().findFragmentByTag(FRAGMENT_TAG);
         if (lifecycleHandler != null) {
             lifecycleHandler.registerActivityListener(activity);
@@ -52,7 +60,8 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         return lifecycleHandler;
     }
 
-    public static LifecycleHandler install(Activity activity) {
+    @NonNull
+    public static LifecycleHandler install(@NonNull Activity activity) {
         LifecycleHandler lifecycleHandler = findInActivity(activity);
         if (lifecycleHandler == null) {
             lifecycleHandler = new LifecycleHandler();
@@ -62,14 +71,18 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         return lifecycleHandler;
     }
 
-    public Router getRouter(ViewGroup container, Bundle savedInstanceState) {
+    @NonNull
+    public Router getRouter(@NonNull ViewGroup container, @Nullable Bundle savedInstanceState) {
         ActivityHostedRouter router = routerMap.get(getRouterHashKey(container));
         if (router == null) {
             router = new ActivityHostedRouter();
             router.setHost(this, container);
 
             if (savedInstanceState != null) {
-                router.restoreInstanceState(savedInstanceState);
+                Bundle routerSavedState = savedInstanceState.getBundle(KEY_ROUTER_STATE_PREFIX + router.getContainerId());
+                if (routerSavedState != null) {
+                    router.restoreInstanceState(routerSavedState);
+                }
             }
             routerMap.put(getRouterHashKey(container), router);
         } else {
@@ -79,19 +92,21 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         return router;
     }
 
+    @NonNull
     public List<Router> getRouters() {
         return new ArrayList<Router>(routerMap.values());
     }
 
+    @Nullable
     public Activity getLifecycleActivity() {
         return activity;
     }
 
-    private static int getRouterHashKey(ViewGroup viewGroup) {
+    private static int getRouterHashKey(@NonNull ViewGroup viewGroup) {
         return viewGroup.getId();
     }
 
-    private void registerActivityListener(Activity activity) {
+    private void registerActivityListener(@NonNull Activity activity) {
         this.activity = activity;
 
         if (!hasRegisteredCallbacks) {
@@ -106,10 +121,13 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
         if (savedInstanceState != null) {
             StringSparseArrayParceler permissionParcel = savedInstanceState.getParcelable(KEY_PERMISSION_REQUEST_CODES);
-            permissionRequestMap = permissionParcel != null ? permissionParcel.getStringSparseArray() : null;
+            permissionRequestMap = permissionParcel != null ? permissionParcel.getStringSparseArray() : new SparseArray<String>();
 
             StringSparseArrayParceler activityParcel = savedInstanceState.getParcelable(KEY_ACTIVITY_REQUEST_CODES);
-            activityRequestMap = activityParcel != null ? activityParcel.getStringSparseArray() : null;
+            activityRequestMap = activityParcel != null ? activityParcel.getStringSparseArray() : new SparseArray<String>();
+
+            ArrayList<PendingPermissionRequest> pendingRequests = savedInstanceState.getParcelableArrayList(KEY_PENDING_PERMISSION_REQUESTS);
+            pendingPermissionRequests = pendingRequests != null ? pendingRequests : new ArrayList<PendingPermissionRequest>();
         }
     }
 
@@ -119,6 +137,7 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
 
         outState.putParcelable(KEY_PERMISSION_REQUEST_CODES, new StringSparseArrayParceler(permissionRequestMap));
         outState.putParcelable(KEY_ACTIVITY_REQUEST_CODES, new StringSparseArrayParceler(activityRequestMap));
+        outState.putParcelableArrayList(KEY_PENDING_PERMISSION_REQUESTS, pendingPermissionRequests);
     }
 
     @Override
@@ -137,21 +156,35 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     public void onAttach(Activity activity) {
         super.onAttach(activity);
         destroyed = false;
+        setAttached();
     }
 
     @Override
     public void onAttach(Context context) {
         super.onAttach(context);
         destroyed = false;
+        setAttached();
     }
 
     @Override
     public void onDetach() {
         super.onDetach();
 
+        attached = false;
         destroyRouters();
     }
 
+    private void setAttached() {
+        if (!attached) {
+            attached = true;
+
+            for (int i = pendingPermissionRequests.size() - 1; i >= 0; i--) {
+                PendingPermissionRequest request = pendingPermissionRequests.remove(i);
+                requestPermissions(request.instanceId, request.permissions, request.requestCode);
+            }
+        }
+    }
+
     private void destroyRouters() {
         if (!destroyed) {
             destroyed = true;
@@ -228,11 +261,11 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         return super.onOptionsItemSelected(item);
     }
 
-    public void registerForActivityResult(String instanceId, int requestCode) {
+    public void registerForActivityResult(@NonNull String instanceId, int requestCode) {
         activityRequestMap.put(requestCode, instanceId);
     }
 
-    public void unregisterForActivityResults(String instanceId) {
+    public void unregisterForActivityResults(@NonNull String instanceId) {
         for (int i = activityRequestMap.size() - 1; i >= 0; i--) {
             if (instanceId.equals(activityRequestMap.get(activityRequestMap.keyAt(i)))) {
                 activityRequestMap.removeAt(i);
@@ -240,20 +273,24 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
         }
     }
 
-    public void startActivityForResult(String instanceId, Intent intent, int requestCode) {
+    public void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode) {
         registerForActivityResult(instanceId, requestCode);
         startActivityForResult(intent, requestCode);
     }
 
-    public void startActivityForResult(String instanceId, Intent intent, int requestCode, Bundle options) {
+    public void startActivityForResult(@NonNull String instanceId, @NonNull Intent intent, int requestCode, @Nullable Bundle options) {
         registerForActivityResult(instanceId, requestCode);
         startActivityForResult(intent, requestCode, options);
     }
 
     @TargetApi(Build.VERSION_CODES.M)
-    public void requestPermissions(String instanceId, String[] permissions, int requestCode) {
-        permissionRequestMap.put(requestCode, instanceId);
-        requestPermissions(permissions, requestCode);
+    public void requestPermissions(@NonNull String instanceId, @NonNull String[] permissions, int requestCode) {
+        if (attached) {
+            permissionRequestMap.put(requestCode, instanceId);
+            requestPermissions(permissions, requestCode);
+        } else {
+            pendingPermissionRequests.add(new PendingPermissionRequest(instanceId, permissions, requestCode));
+        }
     }
 
     @Override
@@ -303,11 +340,56 @@ public class LifecycleHandler extends Fragment implements ActivityLifecycleCallb
     public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
         if (this.activity == activity) {
             for (Router router : routerMap.values()) {
-                router.saveInstanceState(outState);
+                Bundle bundle = new Bundle();
+                router.saveInstanceState(bundle);
+                outState.putBundle(KEY_ROUTER_STATE_PREFIX + router.getContainerId(), bundle);
             }
         }
     }
 
     @Override
     public void onActivityDestroyed(Activity activity) { }
+
+    private static class PendingPermissionRequest implements Parcelable {
+        final String instanceId;
+        final String[] permissions;
+        final int requestCode;
+
+        PendingPermissionRequest(@NonNull String instanceId, @NonNull String[] permissions, int requestCode) {
+            this.instanceId = instanceId;
+            this.permissions = permissions;
+            this.requestCode = requestCode;
+        }
+
+        private PendingPermissionRequest(Parcel in) {
+            instanceId = in.readString();
+            permissions = in.createStringArray();
+            requestCode = in.readInt();
+        }
+
+        @Override
+        public int describeContents() {
+            return 0;
+        }
+
+        @Override
+        public void writeToParcel(Parcel out, int flags) {
+            out.writeString(instanceId);
+            out.writeStringArray(permissions);
+            out.writeInt(requestCode);
+        }
+
+        public static final Parcelable.Creator<PendingPermissionRequest> CREATOR = new Parcelable.Creator<PendingPermissionRequest>() {
+            @Override
+            public PendingPermissionRequest createFromParcel(Parcel in) {
+                return new PendingPermissionRequest(in);
+            }
+
+            @Override
+            public PendingPermissionRequest[] newArray(int size) {
+                return new PendingPermissionRequest[size];
+            }
+        };
+
+    }
 }

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

@@ -1,6 +1,7 @@
 package com.bluelinelabs.conductor.internal;
 
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.view.View;
 import android.view.ViewGroup;
 
@@ -9,7 +10,7 @@ import com.bluelinelabs.conductor.ControllerChangeHandler;
 public class NoOpControllerChangeHandler extends ControllerChangeHandler {
 
     @Override
-    public void performChange(@NonNull ViewGroup container, @NonNull View from, @NonNull View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+    public void performChange(@NonNull ViewGroup container, @Nullable View from, @Nullable View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
         changeListener.onChangeCompleted();
     }
 

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

@@ -2,17 +2,18 @@ package com.bluelinelabs.conductor.internal;
 
 import android.os.Parcel;
 import android.os.Parcelable;
+import android.support.annotation.NonNull;
 import android.util.SparseArray;
 
 public class StringSparseArrayParceler implements Parcelable {
 
     private final SparseArray<String> stringSparseArray;
 
-    public StringSparseArrayParceler(SparseArray<String> stringSparseArray) {
+    public StringSparseArrayParceler(@NonNull SparseArray<String> stringSparseArray) {
         this.stringSparseArray = stringSparseArray;
     }
 
-    private StringSparseArrayParceler(Parcel in) {
+    private StringSparseArrayParceler(@NonNull Parcel in) {
         stringSparseArray = new SparseArray<>();
 
         final int size = in.readInt();
@@ -22,14 +23,17 @@ public class StringSparseArrayParceler implements Parcelable {
         }
     }
 
+    @NonNull
     public SparseArray<String> getStringSparseArray() {
         return stringSparseArray;
     }
 
+    @Override
     public int describeContents() {
         return 0;
     }
 
+    @Override
     public void writeToParcel(Parcel out, int flags) {
         final int size = stringSparseArray.size();
 
@@ -44,10 +48,12 @@ public class StringSparseArrayParceler implements Parcelable {
     }
 
     public static final Parcelable.Creator<StringSparseArrayParceler> CREATOR = new Parcelable.Creator<StringSparseArrayParceler>() {
+        @Override
         public StringSparseArrayParceler createFromParcel(Parcel in) {
             return new StringSparseArrayParceler(in);
         }
 
+        @Override
         public StringSparseArrayParceler[] newArray(int size) {
             return new StringSparseArrayParceler[size];
         }

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

@@ -0,0 +1,72 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import android.support.annotation.IdRes;
+
+import org.robolectric.Robolectric;
+import org.robolectric.util.ActivityController;
+
+public class ActivityProxy {
+
+    private ActivityController<TestActivity> activityController;
+    private AttachFakingFrameLayout view;
+
+    public ActivityProxy() {
+        activityController = Robolectric.buildActivity(TestActivity.class);
+
+        @IdRes int containerId = 4;
+        view = new AttachFakingFrameLayout(activityController.get());
+        view.setId(containerId);
+    }
+
+    public ActivityProxy create(Bundle savedInstanceState) {
+        activityController.create(savedInstanceState);
+        return this;
+    }
+
+    public ActivityProxy start() {
+        activityController.start();
+        view.setAttached(true);
+        return this;
+    }
+
+    public ActivityProxy resume() {
+        activityController.resume();
+        return this;
+    }
+
+    public ActivityProxy pause() {
+        activityController.pause();
+        return this;
+    }
+
+    public ActivityProxy saveInstanceState(Bundle outState) {
+        activityController.saveInstanceState(outState);
+        return this;
+    }
+
+    public ActivityProxy stop() {
+        activityController.stop();
+        view.setAttached(false);
+        return this;
+    }
+
+    public ActivityProxy destroy() {
+        activityController.destroy();
+        return this;
+    }
+
+    public ActivityProxy rotate() {
+        getActivity().isChangingConfigurations = true;
+        getActivity().recreate();
+        return this;
+    }
+
+    public TestActivity getActivity() {
+        return activityController.get();
+    }
+
+    public AttachFakingFrameLayout getView() {
+        return view;
+    }
+}

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

@@ -0,0 +1,113 @@
+package com.bluelinelabs.conductor;
+
+import android.content.Context;
+import android.os.IBinder;
+import android.os.IInterface;
+import android.os.Parcel;
+import android.os.RemoteException;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.FrameLayout;
+
+import java.io.FileDescriptor;
+
+public class AttachFakingFrameLayout extends FrameLayout {
+
+    final IBinder fakeWindowToken = new IBinder() {
+        @Override
+        public String getInterfaceDescriptor() throws RemoteException {
+            return null;
+        }
+
+        @Override
+        public boolean pingBinder() {
+            return false;
+        }
+
+        @Override
+        public boolean isBinderAlive() {
+            return false;
+        }
+
+        @Override
+        public IInterface queryLocalInterface(String descriptor) {
+            return null;
+        }
+
+        @Override
+        public void dump(FileDescriptor fd, String[] args) throws RemoteException {
+
+        }
+
+        @Override
+        public void dumpAsync(FileDescriptor fd, String[] args) throws RemoteException {
+
+        }
+
+        @Override
+        public boolean transact(int code, Parcel data, Parcel reply, int flags) throws RemoteException {
+            return false;
+        }
+
+        @Override
+        public void linkToDeath(DeathRecipient recipient, int flags) throws RemoteException {
+
+        }
+
+        @Override
+        public boolean unlinkToDeath(DeathRecipient recipient, int flags) {
+            return false;
+        }
+    };
+
+    private boolean reportAttached;
+
+    public AttachFakingFrameLayout(Context context) {
+        super(context);
+    }
+
+    public AttachFakingFrameLayout(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public AttachFakingFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    @Override
+    public final IBinder getWindowToken() {
+        return reportAttached ? fakeWindowToken : null;
+    }
+
+    public void setAttached(boolean attached) {
+        setAttached(attached, true);
+    }
+
+    public void setAttached(boolean attached, boolean reportToViewUtils) {
+        if (reportAttached != attached) {
+            reportAttached = attached;
+            if (reportToViewUtils) {
+                ViewUtils.reportAttached(this, attached);
+            }
+
+            for (int i = 0; i < getChildCount(); i++) {
+                ViewUtils.reportAttached(getChildAt(i), attached);
+            }
+        }
+    }
+
+    @Override
+    public void onViewAdded(View child) {
+        if (reportAttached) {
+            ViewUtils.reportAttached(child, true);
+        }
+        super.onViewAdded(child);
+    }
+
+    @Override
+    public void onViewRemoved(View child) {
+        ViewUtils.reportAttached(child, false);
+        super.onViewRemoved(child);
+    }
+
+}

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

@@ -119,9 +119,9 @@ public class CallState implements Parcelable {
                 "\n    restoreInstanceStateCalls=" + restoreInstanceStateCalls +
                 "\n    saveViewStateCalls=" + saveViewStateCalls +
                 "\n    restoreViewStateCalls=" + restoreViewStateCalls +
-                "\n    onActivityResultCalls= " + onActivityResultCalls +
-                "\n    onRequestPermissionsResultCalls= " + onRequestPermissionsResultCalls +
-                "\n    createOptionsMenuCalls= " + createOptionsMenuCalls +
+                "\n    onActivityResultCalls=" + onActivityResultCalls +
+                "\n    onRequestPermissionsResultCalls=" + onRequestPermissionsResultCalls +
+                "\n    createOptionsMenuCalls=" + createOptionsMenuCalls +
                 "}\n";
     }
 

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

@@ -1,41 +1,37 @@
 package com.bluelinelabs.conductor;
 
 import android.os.Bundle;
-import android.support.annotation.IdRes;
 import android.support.annotation.NonNull;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.FrameLayout;
 
 import com.bluelinelabs.conductor.Controller.LifecycleListener;
-import com.bluelinelabs.conductor.ControllerChangeHandler.ControllerChangeCompletedListener;
+import com.bluelinelabs.conductor.MockChangeHandler.ChangeHandlerListener;
 
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
-import org.robolectric.util.ActivityController;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class ControllerLifecycleTests {
 
-    private ActivityController<TestActivity> activityController;
     private Router router;
 
+    private ActivityProxy activityProxy;
     private CallState currentCallState;
 
-    public void createActivityController(Bundle savedInstanceState) {
-        activityController = Robolectric.buildActivity(TestActivity.class).create(savedInstanceState).start();
+    public void createActivityController(Bundle savedInstanceState, boolean includeStartAndResume) {
+        activityProxy = new ActivityProxy().create(savedInstanceState);
 
-        @IdRes int containerId = 4;
-        FrameLayout routerContainer = new FrameLayout(activityController.get());
-        routerContainer.setId(containerId);
+        if (includeStartAndResume) {
+            activityProxy.start().resume();
+        }
 
-        router = Conductor.attachRouter(activityController.get(), routerContainer, savedInstanceState);
+        router = Conductor.attachRouter(activityProxy.getActivity(), activityProxy.getView(), savedInstanceState);
         if (!router.hasRootController()) {
             router.setRoot(RouterTransaction.with(new TestController()));
         }
@@ -43,7 +39,7 @@ public class ControllerLifecycleTests {
 
     @Before
     public void setup() {
-        createActivityController(null);
+        createActivityController(null, true);
 
         currentCallState = new CallState();
     }
@@ -82,18 +78,20 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, controller);
 
-        activityController.pause();
+        activityProxy.getActivity().isDestroying = true;
+        activityProxy.pause();
 
         assertCalls(expectedCallState, controller);
 
-        activityController.stop();
-
-        assertCalls(expectedCallState, controller);
-
-        activityController.destroy();
+        activityProxy.stop();
 
+        expectedCallState.saveViewStateCalls++;
         expectedCallState.detachCalls++;
         expectedCallState.destroyViewCalls++;
+        assertCalls(expectedCallState, controller);
+
+        activityProxy.destroy();
+
         expectedCallState.destroyCalls++;
         assertCalls(expectedCallState, controller);
     }
@@ -112,33 +110,32 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, controller);
 
-        activityController.get().isChangingConfigurations = true;
+        activityProxy.getActivity().isChangingConfigurations = true;
 
         Bundle bundle = new Bundle();
-        activityController.saveInstanceState(bundle);
+        activityProxy.saveInstanceState(bundle);
 
         expectedCallState.saveViewStateCalls++;
         expectedCallState.saveInstanceStateCalls++;
         assertCalls(expectedCallState, controller);
 
-        activityController.pause();
+        activityProxy.pause();
         assertCalls(expectedCallState, controller);
 
-        activityController.stop();
-        assertCalls(expectedCallState, controller);
-
-        activityController.destroy();
+        activityProxy.stop();
         expectedCallState.detachCalls++;
         expectedCallState.destroyViewCalls++;
         assertCalls(expectedCallState, controller);
 
-        createActivityController(bundle);
+        activityProxy.destroy();
+        assertCalls(expectedCallState, controller);
+
+        createActivityController(bundle, false);
         controller = (TestController)router.getControllerWithTag("root");
 
         expectedCallState.restoreInstanceStateCalls++;
         expectedCallState.restoreViewStateCalls++;
         expectedCallState.changeStartCalls++;
-        expectedCallState.changeEndCalls++;
         expectedCallState.createViewCalls++;
 
         // Lifecycle listener isn't attached during restore, grab the current views from the controller for this stuff...
@@ -147,10 +144,19 @@ public class ControllerLifecycleTests {
         currentCallState.changeStartCalls = controller.currentCallState.changeStartCalls;
         currentCallState.changeEndCalls = controller.currentCallState.changeEndCalls;
         currentCallState.createViewCalls = controller.currentCallState.createViewCalls;
+        currentCallState.attachCalls = controller.currentCallState.attachCalls;
 
         assertCalls(expectedCallState, controller);
 
-        activityController.resume();
+        activityProxy.start().resume();
+        currentCallState.changeEndCalls = controller.currentCallState.changeEndCalls;
+        currentCallState.attachCalls = controller.currentCallState.attachCalls;
+        expectedCallState.changeEndCalls++;
+        expectedCallState.attachCalls++;
+
+        assertCalls(expectedCallState, controller);
+
+        activityProxy.resume();
         assertCalls(expectedCallState, controller);
     }
 
@@ -167,16 +173,16 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, controller);
 
-        activityController.pause();
+        activityProxy.pause();
 
         Bundle bundle = new Bundle();
-        activityController.saveInstanceState(bundle);
+        activityProxy.saveInstanceState(bundle);
 
         expectedCallState.saveInstanceStateCalls++;
         expectedCallState.saveViewStateCalls++;
         assertCalls(expectedCallState, controller);
 
-        activityController.resume();
+        activityProxy.resume();
     }
 
     @Test
@@ -377,22 +383,8 @@ public class ControllerLifecycleTests {
         });
 
         router.pushController(RouterTransaction.with(testController)
-                .pushChangeHandler(new ChangeHandler(new ChangeHandlerListener() {
-                    @Override
-                    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-                        container.addView(to);
-                        ViewUtils.setAttached(to, true);
-                        changeListener.onChangeCompleted();
-                    }
-                }))
-                .popChangeHandler(new ChangeHandler(new ChangeHandlerListener() {
-                    @Override
-                    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-                        container.removeView(from);
-                        ViewUtils.setAttached(from, false);
-                        changeListener.onChangeCompleted();
-                    }
-                })));
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
 
         router.popController(testController);
 
@@ -407,14 +399,7 @@ public class ControllerLifecycleTests {
     public void testChildLifecycle() {
         Controller parent = new TestController();
         router.pushController(RouterTransaction.with(parent)
-                .pushChangeHandler(new ChangeHandler(new ChangeHandlerListener() {
-                    @Override
-                    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-                        container.addView(to);
-                        ViewUtils.setAttached(to, true);
-                        changeListener.onChangeCompleted();
-                    }
-                })));
+                .pushChangeHandler(new MockChangeHandler()));
 
         TestController child = new TestController();
         attachLifecycleListener(child);
@@ -423,7 +408,7 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, child);
 
-        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null);
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
             childRouter
                 .setRoot(RouterTransaction.with(child)
                         .pushChangeHandler(getPushHandler(expectedCallState, child))
@@ -440,22 +425,8 @@ public class ControllerLifecycleTests {
     public void testChildLifecycle2() {
         Controller parent = new TestController();
         router.pushController(RouterTransaction.with(parent)
-                .pushChangeHandler(new ChangeHandler(new ChangeHandlerListener() {
-                    @Override
-                    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-                        container.addView(to);
-                        ViewUtils.setAttached(to, true);
-                        changeListener.onChangeCompleted();
-                    }
-                }))
-                .popChangeHandler(new ChangeHandler(new ChangeHandlerListener() {
-                    @Override
-                    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-                        container.removeView(from);
-                        ViewUtils.setAttached(from, false);
-                        changeListener.onChangeCompleted();
-                    }
-                })));
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
 
         TestController child = new TestController();
         attachLifecycleListener(child);
@@ -464,7 +435,7 @@ public class ControllerLifecycleTests {
 
         assertCalls(expectedCallState, child);
 
-        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null);
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
         childRouter
                 .setRoot(RouterTransaction.with(child)
                         .pushChangeHandler(getPushHandler(expectedCallState, child))
@@ -477,44 +448,47 @@ public class ControllerLifecycleTests {
         assertCalls(expectedCallState, child);
     }
 
-    private ChangeHandler getPushHandler(final CallState expectedCallState, final TestController controller) {
-        return new ChangeHandler(new ChangeHandlerListener() {
+    private MockChangeHandler getPushHandler(final CallState expectedCallState, final TestController controller) {
+        return new MockChangeHandler(new ChangeHandlerListener() {
             @Override
-            public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+            void willStartChange() {
                 expectedCallState.changeStartCalls++;
                 expectedCallState.createViewCalls++;
                 assertCalls(expectedCallState, controller);
+            }
 
-                container.addView(to);
-                ViewUtils.setAttached(to, true);
-
+            @Override
+            void didAttachOrDetach() {
                 expectedCallState.attachCalls++;
                 assertCalls(expectedCallState, controller);
+            }
 
-                changeListener.onChangeCompleted();
-
+            @Override
+            void didEndChange() {
                 expectedCallState.changeEndCalls++;
                 assertCalls(expectedCallState, controller);
             }
         });
     }
 
-    private ChangeHandler getPopHandler(final CallState expectedCallState, final TestController controller) {
-        return new ChangeHandler(new ChangeHandlerListener() {
+    private MockChangeHandler getPopHandler(final CallState expectedCallState, final TestController controller) {
+        return new MockChangeHandler(new ChangeHandlerListener() {
             @Override
-            public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+            void willStartChange() {
                 expectedCallState.changeStartCalls++;
                 assertCalls(expectedCallState, controller);
-                container.removeView(from);
-                ViewUtils.setAttached(from, false);
+            }
 
+            @Override
+            void didAttachOrDetach() {
                 expectedCallState.destroyViewCalls++;
                 expectedCallState.detachCalls++;
                 expectedCallState.destroyCalls++;
                 assertCalls(expectedCallState, controller);
+            }
 
-                changeListener.onChangeCompleted();
-
+            @Override
+            void didEndChange() {
                 expectedCallState.changeEndCalls++;
                 assertCalls(expectedCallState, controller);
             }
@@ -585,24 +559,4 @@ public class ControllerLifecycleTests {
         });
     }
 
-    interface ChangeHandlerListener {
-        void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener);
-    }
-
-    public static class ChangeHandler extends ControllerChangeHandler {
-
-        private ChangeHandlerListener listener;
-
-        public ChangeHandler() { }
-
-        public ChangeHandler(ChangeHandlerListener listener) {
-            this.listener = listener;
-        }
-
-        @Override
-        public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
-            listener.performChange(container, from, to, isPush, changeListener);
-        }
-    }
-
 }

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

@@ -3,10 +3,8 @@ package com.bluelinelabs.conductor;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
-import android.support.annotation.IdRes;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.FrameLayout;
 
 import com.bluelinelabs.conductor.Controller.RetainViewMode;
 
@@ -14,26 +12,19 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
-import org.robolectric.util.ActivityController;
 
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class ControllerTests {
 
-    private ActivityController<TestActivity> activityController;
+    private ActivityProxy activityProxy;
     private Router router;
 
     public void createActivityController(Bundle savedInstanceState) {
-        activityController = Robolectric.buildActivity(TestActivity.class).create(savedInstanceState).start();
-
-        @IdRes int containerId = 4;
-        FrameLayout routerContainer = new FrameLayout(activityController.get());
-        routerContainer.setId(containerId);
-
-        router = Conductor.attachRouter(activityController.get(), routerContainer, 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()));
         }
@@ -47,24 +38,25 @@ public class ControllerTests {
     @Test
     public void testViewRetention() {
         Controller controller = new TestController();
+        controller.setRouter(router);
 
         // Test View getting released w/ RELEASE_DETACH
         controller.setRetainViewMode(RetainViewMode.RELEASE_DETACH);
         Assert.assertNull(controller.getView());
-        View view = controller.inflate(new FrameLayout(router.getActivity()));
+        View view = controller.inflate(router.container);
         Assert.assertNotNull(controller.getView());
-        ViewUtils.setAttached(view, true);
+        ViewUtils.reportAttached(view, true);
         Assert.assertNotNull(controller.getView());
-        ViewUtils.setAttached(view, false);
+        ViewUtils.reportAttached(view, false);
         Assert.assertNull(controller.getView());
 
         // Test View getting retained w/ RETAIN_DETACH
         controller.setRetainViewMode(RetainViewMode.RETAIN_DETACH);
-        view = controller.inflate(new FrameLayout(router.getActivity()));
+        view = controller.inflate(router.container);
         Assert.assertNotNull(controller.getView());
-        ViewUtils.setAttached(view, true);
+        ViewUtils.reportAttached(view, true);
         Assert.assertNotNull(controller.getView());
-        ViewUtils.setAttached(view, false);
+        ViewUtils.reportAttached(view, false);
         Assert.assertNotNull(controller.getView());
 
         // Ensure re-setting RELEASE_DETACH releases
@@ -78,7 +70,6 @@ public class ControllerTests {
         CallState expectedCallState = new CallState(true);
 
         router.pushController(RouterTransaction.with(controller));
-        ViewUtils.setAttached(controller.getView(), true);
 
         // Ensure that calling onActivityResult w/o requesting a result doesn't do anything
         router.onActivityResult(1, Activity.RESULT_OK, null);
@@ -103,10 +94,8 @@ public class ControllerTests {
         TestController child = new TestController();
 
         router.pushController(RouterTransaction.with(parent));
-        ViewUtils.setAttached(parent.getView(), true);
-        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null)
+        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID))
                 .setRoot(RouterTransaction.with(child));
-        ViewUtils.setAttached(child.getView(), true);
 
         CallState childExpectedCallState = new CallState(true);
         CallState parentExpectedCallState = new CallState(true);
@@ -139,7 +128,6 @@ public class ControllerTests {
         CallState expectedCallState = new CallState(true);
 
         router.pushController(RouterTransaction.with(controller));
-        ViewUtils.setAttached(controller.getView(), true);
 
         // Ensure that calling handleRequestedPermission w/o requesting a result doesn't do anything
         router.onRequestPermissionsResult("anotherId", 1, requestedPermissions, new int[] {1});
@@ -163,10 +151,8 @@ public class ControllerTests {
         TestController child = new TestController();
 
         router.pushController(RouterTransaction.with(parent));
-        ViewUtils.setAttached(parent.getView(), true);
-        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null)
+        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID))
                 .setRoot(RouterTransaction.with(child));
-        ViewUtils.setAttached(child.getView(), true);
 
         CallState childExpectedCallState = new CallState(true);
         CallState parentExpectedCallState = new CallState(true);
@@ -193,7 +179,6 @@ public class ControllerTests {
         CallState expectedCallState = new CallState(true);
 
         router.pushController(RouterTransaction.with(controller));
-        ViewUtils.setAttached(controller.getView(), true);
 
         // Ensure that calling onCreateOptionsMenu w/o declaring that we have one doesn't do anything
         router.onCreateOptionsMenu(null, null);
@@ -230,10 +215,8 @@ public class ControllerTests {
         TestController child = new TestController();
 
         router.pushController(RouterTransaction.with(parent));
-        ViewUtils.setAttached(parent.getView(), true);
-        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null)
+        parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID))
                 .setRoot(RouterTransaction.with(child));
-        ViewUtils.setAttached(child.getView(), true);
 
         CallState childExpectedCallState = new CallState(true);
         CallState parentExpectedCallState = new CallState(true);
@@ -284,7 +267,8 @@ public class ControllerTests {
         Assert.assertNull(child1.getParentController());
         Assert.assertNull(child2.getParentController());
 
-        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null);
+        Router childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
         childRouter.setRoot(RouterTransaction.with(child1));
 
         Assert.assertEquals(1, parent.getChildRouters().size());
@@ -294,7 +278,7 @@ public class ControllerTests {
         Assert.assertEquals(parent, child1.getParentController());
         Assert.assertNull(child2.getParentController());
 
-        childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID), null);
+        childRouter = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.VIEW_ID));
         childRouter.pushController(RouterTransaction.with(child2));
 
         Assert.assertEquals(1, parent.getChildRouters().size());
@@ -336,8 +320,8 @@ public class ControllerTests {
         Assert.assertNull(child1.getParentController());
         Assert.assertNull(child2.getParentController());
 
-        Router childRouter1 = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_1), null);
-        Router childRouter2 = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_2), null);
+        Router childRouter1 = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_1));
+        Router childRouter2 = parent.getChildRouter((ViewGroup)parent.getView().findViewById(TestController.CHILD_VIEW_ID_2));
 
         childRouter1.setRoot(RouterTransaction.with(child1));
         childRouter2.setRoot(RouterTransaction.with(child2));

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

@@ -0,0 +1,85 @@
+package com.bluelinelabs.conductor;
+
+
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.view.View;
+import android.view.ViewGroup;
+
+public class MockChangeHandler extends ControllerChangeHandler {
+
+    private static final String KEY_REMOVES_FROM_VIEW_ON_PUSH = "MockChangeHandler.removesFromViewOnPush";
+
+    static class ChangeHandlerListener {
+        void willStartChange() { }
+        void didAttachOrDetach() { }
+        void didEndChange() { }
+    }
+
+    final ChangeHandlerListener listener;
+    boolean removesFromViewOnPush;
+
+    public MockChangeHandler() {
+        this(true, null);
+    }
+
+    public MockChangeHandler(boolean removesViewOnPush) {
+        this(removesViewOnPush, null);
+    }
+
+    public MockChangeHandler(@NonNull ChangeHandlerListener listener) {
+        this(true, listener);
+    }
+
+    public MockChangeHandler(boolean removesFromViewOnPush, ChangeHandlerListener listener) {
+        this.removesFromViewOnPush = removesFromViewOnPush;
+
+        if (listener == null) {
+            this.listener = new ChangeHandlerListener() { };
+        } else {
+            this.listener = listener;
+        }
+    }
+
+    @Override
+    public void performChange(@NonNull ViewGroup container, View from, View to, boolean isPush, @NonNull ControllerChangeCompletedListener changeListener) {
+        listener.willStartChange();
+
+        if (isPush) {
+            container.addView(to);
+            listener.didAttachOrDetach();
+
+            if (removesFromViewOnPush && from != null) {
+                container.removeView(from);
+            }
+        } else {
+            container.removeView(from);
+            listener.didAttachOrDetach();
+
+            if (to != null) {
+                container.addView(to);
+            }
+
+        }
+
+        changeListener.onChangeCompleted();
+        listener.didEndChange();
+    }
+
+    @Override
+    public boolean removesFromViewOnPush() {
+        return removesFromViewOnPush;
+    }
+
+    @Override
+    public void saveToBundle(@NonNull Bundle bundle) {
+        super.saveToBundle(bundle);
+        bundle.putBoolean(KEY_REMOVES_FROM_VIEW_ON_PUSH, removesFromViewOnPush);
+    }
+
+    @Override
+    public void restoreFromBundle(@NonNull Bundle bundle) {
+        super.restoreFromBundle(bundle);
+        removesFromViewOnPush = bundle.getBoolean(KEY_REMOVES_FROM_VIEW_ON_PUSH);
+    }
+}

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

@@ -0,0 +1,234 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import android.view.ViewGroup;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class ReattachCaseTests {
+
+    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 testNeedsAttachingOnPauseAndOrientation() {
+        final TestController controllerA = new TestController();
+        final TestController controllerB = new TestController();
+
+        router.pushController(RouterTransaction.with(controllerA)
+            .pushChangeHandler(new MockChangeHandler())
+            .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+
+        sleepWakeDevice();
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+
+        router.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+
+        activityProxy.rotate();
+        router.rebindIfNeeded();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+    }
+
+    @Test
+    public void testChildNeedsAttachOnPauseAndOrientation() {
+        final TestController controllerA = new TestController();
+        final TestController childController = new TestController();
+        final TestController controllerB = new TestController();
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Router childRouter = controllerA.getChildRouter((ViewGroup)controllerA.getView().findViewById(TestController.VIEW_ID));
+        childRouter.pushController(RouterTransaction.with(childController)
+            .pushChangeHandler(new MockChangeHandler())
+            .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertTrue(childController.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+
+        sleepWakeDevice();
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertTrue(childController.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+
+        router.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertFalse(childController.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+
+        activityProxy.rotate();
+        router.rebindIfNeeded();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertFalse(childController.isAttached());
+        Assert.assertTrue(childController.getNeedsAttach());
+        Assert.assertTrue(controllerB.isAttached());
+    }
+
+    @Test
+    public void testChildHandleBackOnOrientation() {
+        final TestController controllerA = new TestController();
+        final TestController controllerB = new TestController();
+        final TestController childController = new TestController();
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+
+        router.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Router childRouter = controllerB.getChildRouter((ViewGroup)controllerB.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
+        childRouter.pushController(RouterTransaction.with(childController)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        activityProxy.rotate();
+        router.rebindIfNeeded();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        router.handleBack();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+
+        router.handleBack();
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+    }
+
+    // Attempt to test https://github.com/bluelinelabs/Conductor/issues/86#issuecomment-231381271
+    @Test
+    public void testReusedChildRouterHandleBackOnOrientation() {
+        TestController controllerA = new TestController();
+        TestController controllerB = new TestController();
+        TestController childController = new TestController();
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+
+        router.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Router childRouter = controllerB.getChildRouter((ViewGroup)controllerB.getView().findViewById(TestController.VIEW_ID));
+        childRouter.setPopsLastView(true);
+        childRouter.pushController(RouterTransaction.with(childController)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        router.handleBack();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+
+        childController = new TestController();
+        childRouter.pushController(RouterTransaction.with(childController)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        activityProxy.rotate();
+        router.rebindIfNeeded();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        router.handleBack();
+
+        childController = new TestController();
+        childRouter.pushController(RouterTransaction.with(childController)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertTrue(childController.isAttached());
+
+        router.handleBack();
+
+        Assert.assertFalse(controllerA.isAttached());
+        Assert.assertTrue(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+
+        router.handleBack();
+
+        Assert.assertTrue(controllerA.isAttached());
+        Assert.assertFalse(controllerB.isAttached());
+        Assert.assertFalse(childController.isAttached());
+    }
+
+    private void sleepWakeDevice() {
+        activityProxy.saveInstanceState(new Bundle()).pause();
+        activityProxy.resume();
+    }
+
+}

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

@@ -1,16 +1,15 @@
 package com.bluelinelabs.conductor;
 
-import android.app.Activity;
-import android.widget.FrameLayout;
-
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import org.robolectric.Robolectric;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.annotation.Config;
 
+import java.util.ArrayList;
+import java.util.List;
+
 @RunWith(RobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class RouterTests {
@@ -19,8 +18,8 @@ public class RouterTests {
 
     @Before
     public void setup() {
-        Activity activity = Robolectric.buildActivity(TestActivity.class).create().get();
-        router = Conductor.attachRouter(activity, new FrameLayout(activity), null);
+        ActivityProxy activityProxy = new ActivityProxy().create(null).start().resume();
+        router = Conductor.attachRouter(activityProxy.getActivity(), activityProxy.getView(), null);
     }
 
     @Test
@@ -174,4 +173,149 @@ public class RouterTests {
         Assert.assertEquals(controller3, router.getControllerWithTag(controller3Tag));
     }
 
+    @Test
+    public void testSetBackstack() {
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction middleTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction topTransaction = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = new ArrayList<>();
+        backstack.add(rootTransaction);
+        backstack.add(middleTransaction);
+        backstack.add(topTransaction);
+
+        router.setBackstack(backstack, null);
+
+        Assert.assertEquals(3, router.getBackstackSize());
+
+        List<RouterTransaction> fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(middleTransaction, fetchedBackstack.get(1));
+        Assert.assertEquals(topTransaction, fetchedBackstack.get(2));
+    }
+
+    @Test
+    public void testNewSetBackstack() {
+        router.setRoot(RouterTransaction.with(new TestController()));
+
+        Assert.assertEquals(1, router.getBackstackSize());
+
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction middleTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction topTransaction = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = new ArrayList<>();
+        backstack.add(rootTransaction);
+        backstack.add(middleTransaction);
+        backstack.add(topTransaction);
+
+        router.setBackstack(backstack, null);
+
+        Assert.assertEquals(3, router.getBackstackSize());
+
+        List<RouterTransaction> fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(middleTransaction, fetchedBackstack.get(1));
+        Assert.assertEquals(topTransaction, fetchedBackstack.get(2));
+    }
+
+    @Test
+    public void testNewSetBackstackWithNoRemoveViewOnPush() {
+        RouterTransaction oldRootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction oldTopTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new MockChangeHandler(false));
+
+        router.setRoot(oldRootTransaction);
+        router.pushController(oldTopTransaction);
+        Assert.assertEquals(2, router.getBackstackSize());
+
+        Assert.assertTrue(oldRootTransaction.controller.isAttached());
+        Assert.assertTrue(oldTopTransaction.controller.isAttached());
+
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction middleTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new MockChangeHandler(false));
+        RouterTransaction topTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new MockChangeHandler(false));
+
+        List<RouterTransaction> backstack = new ArrayList<>();
+        backstack.add(rootTransaction);
+        backstack.add(middleTransaction);
+        backstack.add(topTransaction);
+
+        router.setBackstack(backstack, null);
+
+        Assert.assertEquals(3, router.getBackstackSize());
+
+        List<RouterTransaction> fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(middleTransaction, fetchedBackstack.get(1));
+        Assert.assertEquals(topTransaction, fetchedBackstack.get(2));
+
+        Assert.assertFalse(oldRootTransaction.controller.isAttached());
+        Assert.assertFalse(oldTopTransaction.controller.isAttached());
+        Assert.assertTrue(rootTransaction.controller.isAttached());
+        Assert.assertTrue(middleTransaction.controller.isAttached());
+        Assert.assertTrue(topTransaction.controller.isAttached());
+    }
+
+    @Test
+    public void testReplaceTopController() {
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction topTransaction = RouterTransaction.with(new TestController());
+
+        List<RouterTransaction> backstack = new ArrayList<>();
+        backstack.add(rootTransaction);
+        backstack.add(topTransaction);
+
+        router.setBackstack(backstack, null);
+
+        Assert.assertEquals(2, router.getBackstackSize());
+
+        List<RouterTransaction> fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(topTransaction, fetchedBackstack.get(1));
+
+        RouterTransaction newTopTransaction = RouterTransaction.with(new TestController());
+        router.replaceTopController(newTopTransaction);
+
+        Assert.assertEquals(2, router.getBackstackSize());
+
+        fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(newTopTransaction, fetchedBackstack.get(1));
+    }
+
+    @Test
+    public void testReplaceTopControllerWithNoRemoveViewOnPush() {
+        RouterTransaction rootTransaction = RouterTransaction.with(new TestController());
+        RouterTransaction topTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new MockChangeHandler(false));
+
+        List<RouterTransaction> backstack = new ArrayList<>();
+        backstack.add(rootTransaction);
+        backstack.add(topTransaction);
+
+        router.setBackstack(backstack, null);
+
+        Assert.assertEquals(2, router.getBackstackSize());
+
+        Assert.assertTrue(rootTransaction.controller.isAttached());
+        Assert.assertTrue(topTransaction.controller.isAttached());
+
+        List<RouterTransaction> fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(topTransaction, fetchedBackstack.get(1));
+
+        RouterTransaction newTopTransaction = RouterTransaction.with(new TestController()).pushChangeHandler(new MockChangeHandler(false));
+        router.replaceTopController(newTopTransaction);
+        newTopTransaction.pushChangeHandler().completeImmediately();
+
+        Assert.assertEquals(2, router.getBackstackSize());
+
+        fetchedBackstack = router.getBackstack();
+        Assert.assertEquals(rootTransaction, fetchedBackstack.get(0));
+        Assert.assertEquals(newTopTransaction, fetchedBackstack.get(1));
+
+        Assert.assertTrue(rootTransaction.controller.isAttached());
+        Assert.assertFalse(topTransaction.controller.isAttached());
+        Assert.assertTrue(newTopTransaction.controller.isAttached());
+    }
+
 }

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

@@ -0,0 +1,100 @@
+package com.bluelinelabs.conductor;
+
+import android.os.Bundle;
+import android.view.ViewGroup;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class TargetControllerTests {
+
+    private Router router;
+
+    public void createActivityController(Bundle savedInstanceState) {
+        ActivityProxy 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 testSiblingTarget() {
+        final TestController controllerA = new TestController();
+        final TestController controllerB = new TestController();
+
+        Assert.assertNull(controllerA.getTargetController());
+        Assert.assertNull(controllerB.getTargetController());
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        controllerB.setTargetController(controllerA);
+
+        router.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertNull(controllerA.getTargetController());
+        Assert.assertEquals(controllerA, controllerB.getTargetController());
+    }
+
+    @Test
+    public void testParentChildTarget() {
+        final TestController controllerA = new TestController();
+        final TestController controllerB = new TestController();
+
+        Assert.assertNull(controllerA.getTargetController());
+        Assert.assertNull(controllerB.getTargetController());
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        controllerB.setTargetController(controllerA);
+
+        Router childRouter = controllerA.getChildRouter((ViewGroup)controllerA.getView().findViewById(TestController.VIEW_ID));
+        childRouter.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertNull(controllerA.getTargetController());
+        Assert.assertEquals(controllerA, controllerB.getTargetController());
+    }
+
+    @Test
+    public void testChildParentTarget() {
+        final TestController controllerA = new TestController();
+        final TestController controllerB = new TestController();
+
+        Assert.assertNull(controllerA.getTargetController());
+        Assert.assertNull(controllerB.getTargetController());
+
+        router.pushController(RouterTransaction.with(controllerA)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        controllerA.setTargetController(controllerB);
+
+        Router childRouter = controllerA.getChildRouter((ViewGroup)controllerA.getView().findViewById(TestController.VIEW_ID));
+        childRouter.pushController(RouterTransaction.with(controllerB)
+                .pushChangeHandler(new MockChangeHandler())
+                .popChangeHandler(new MockChangeHandler()));
+
+        Assert.assertNull(controllerB.getTargetController());
+        Assert.assertEquals(controllerB, controllerA.getTargetController());
+    }
+
+}

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

@@ -5,10 +5,15 @@ import android.app.Activity;
 public class TestActivity extends Activity {
 
     public boolean isChangingConfigurations = false;
+    public boolean isDestroying = false;
 
     @Override
     public boolean isChangingConfigurations() {
         return isChangingConfigurations;
     }
 
+    @Override
+    public boolean isDestroyed() {
+        return isDestroying || super.isDestroyed();
+    }
 }

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

@@ -29,7 +29,7 @@ public class TestController extends Controller {
     @Override
     protected View onCreateView(@NonNull LayoutInflater inflater, @NonNull ViewGroup container) {
         currentCallState.createViewCalls++;
-        FrameLayout view = new FrameLayout(inflater.getContext());
+        FrameLayout view = new AttachFakingFrameLayout(inflater.getContext());
         view.setId(VIEW_ID);
 
         FrameLayout childContainer1 = new FrameLayout(inflater.getContext());
@@ -68,7 +68,7 @@ public class TestController extends Controller {
     }
 
     @Override
-    protected void onDestroyView(View view) {
+    protected void onDestroyView(@NonNull View view) {
         super.onDestroyView(view);
         currentCallState.destroyViewCalls++;
     }

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

@@ -9,9 +9,26 @@ import java.util.List;
 
 public class ViewUtils {
 
-    static void setAttached(View view, boolean attached) {
-        Object listenerInfo = ReflectionHelpers.callInstanceMethod(view, "getListenerInfo");
-        List<OnAttachStateChangeListener> listeners = ReflectionHelpers.getField(listenerInfo, "mOnAttachStateChangeListeners");
+    public static void reportAttached(View view, boolean attached) {
+        if (view instanceof AttachFakingFrameLayout) {
+            ((AttachFakingFrameLayout)view).setAttached(attached, false);
+        }
+
+        List<OnAttachStateChangeListener> listeners = getAttachStateListeners(view);
+
+        // Add, then remove an OnAttachStateChangeListener to initialize the attachStateListeners variable inside a view
+        if (listeners == null) {
+            OnAttachStateChangeListener tmpListener = new OnAttachStateChangeListener() {
+                @Override
+                public void onViewAttachedToWindow(View v) { }
+
+                @Override
+                public void onViewDetachedFromWindow(View v) { }
+            };
+            view.addOnAttachStateChangeListener(tmpListener);
+            view.removeOnAttachStateChangeListener(tmpListener);
+            listeners = getAttachStateListeners(view);
+        }
 
         for (OnAttachStateChangeListener listener : listeners) {
             if (attached) {
@@ -20,6 +37,12 @@ public class ViewUtils {
                 listener.onViewDetachedFromWindow(view);
             }
         }
+
+    }
+
+    private static List<OnAttachStateChangeListener> getAttachStateListeners(View view) {
+        Object listenerInfo = ReflectionHelpers.callInstanceMethod(view, "getListenerInfo");
+        return ReflectionHelpers.getField(listenerInfo, "mOnAttachStateChangeListeners");
     }
 
 }

demo/src/main/java/com/bluelinelabs/conductor/demo/MainActivity.java

@@ -12,22 +12,20 @@ import com.bluelinelabs.conductor.demo.controllers.HomeController;
 
 import butterknife.BindView;
 import butterknife.ButterKnife;
-import butterknife.Unbinder;
 
-public class MainActivity extends AppCompatActivity implements ActionBarProvider {
+public final class MainActivity extends AppCompatActivity implements ActionBarProvider {
 
     @BindView(R.id.toolbar) Toolbar toolbar;
     @BindView(R.id.controller_container) ViewGroup container;
 
     private Router router;
-    private Unbinder unbinder;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
         setContentView(R.layout.activity_main);
-        unbinder = ButterKnife.bind(this);
+        ButterKnife.bind(this);
 
         setSupportActionBar(toolbar);
 
@@ -44,10 +42,4 @@ public class MainActivity extends AppCompatActivity implements ActionBarProvider
         }
     }
 
-    @Override
-    protected void onDestroy() {
-        super.onDestroy();
-        unbinder.unbind();
-    }
-
 }

demo/src/main/java/com/bluelinelabs/conductor/demo/changehandler/CircularRevealChangeHandler.java

@@ -120,7 +120,7 @@ public class CircularRevealChangeHandler extends AnimatorChangeHandler {
         this.cy = cy;
     }
 
-    @Override
+    @Override @NonNull
     protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
         final float radius = (float) Math.hypot(cx, cy);
         Animator animator = null;

demo/src/main/java/com/bluelinelabs/conductor/demo/changehandler/CircularRevealChangeHandlerCompat.java

@@ -16,7 +16,7 @@ public class CircularRevealChangeHandlerCompat extends CircularRevealChangeHandl
         super(fromView, containerView);
     }
 
-    @Override
+    @Override @NonNull
     protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
             return super.getAnimator(container, from, to, isPush, toAddedToContainer);

demo/src/main/java/com/bluelinelabs/conductor/demo/changehandler/FlipChangeHandler.java

@@ -52,7 +52,7 @@ public class FlipChangeHandler extends AnimatorChangeHandler {
         this.animationDuration = animationDuration;
     }
 
-    @Override
+    @Override @NonNull
     protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
         AnimatorSet animatorSet = new AnimatorSet();
 

demo/src/main/java/com/bluelinelabs/conductor/demo/changehandler/ScaleFadeChangeHandler.java

@@ -15,7 +15,7 @@ public class ScaleFadeChangeHandler extends AnimatorChangeHandler {
         super(DEFAULT_ANIMATION_DURATION, true);
     }
 
-    @Override
+    @Override @NonNull
     protected Animator getAnimator(@NonNull ViewGroup container, View from, View to, boolean isPush, boolean toAddedToContainer) {
         AnimatorSet animator = new AnimatorSet();
         if (to != null && toAddedToContainer) {

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/DragDismissController.java

@@ -46,7 +46,7 @@ public class DragDismissController extends BaseController {
     }
 
     @Override
-    protected void onDestroyView(View view) {
+    protected void onDestroyView(@NonNull View view) {
         super.onDestroyView(view);
 
         ((ElasticDragDismissFrameLayout)view).removeListener(dragDismissListener);

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/HomeController.java

@@ -27,6 +27,7 @@ import com.bluelinelabs.conductor.ControllerChangeType;
 import com.bluelinelabs.conductor.RouterTransaction;
 import com.bluelinelabs.conductor.changehandler.FadeChangeHandler;
 import com.bluelinelabs.conductor.demo.R;
+import com.bluelinelabs.conductor.demo.controllers.NavigationDemoController.DisplayUpMode;
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController;
 
 import butterknife.BindView;
@@ -79,7 +80,7 @@ public class HomeController extends BaseController {
     }
 
     @Override
-    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+    public void onCreateOptionsMenu(@NonNull Menu menu, @NonNull MenuInflater inflater) {
         super.onCreateOptionsMenu(menu, inflater);
         inflater.inflate(R.menu.home, menu);
     }
@@ -94,7 +95,7 @@ public class HomeController extends BaseController {
     }
 
     @Override
-    public boolean onOptionsItemSelected(MenuItem item) {
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
         if (item.getItemId() == R.id.about) {
             SpannableString details = new SpannableString("A small, yet full-featured framework that allows building View-based Android applications");
             details.setSpan(new AbsoluteSizeSpan(16, true), 0, details.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
@@ -115,7 +116,7 @@ public class HomeController extends BaseController {
             content.append("\n\n");
             content.append(link);
 
-            getChildRouter(overlayRoot, null)
+            getChildRouter(overlayRoot)
                     .setPopsLastView(true)
                     .setRoot(RouterTransaction.with(new OverlayController(content))
                             .pushChangeHandler(new FadeChangeHandler())
@@ -133,7 +134,7 @@ public class HomeController extends BaseController {
     void onModelRowClick(HomeDemoModel model) {
         switch (model) {
             case NAVIGATION:
-                getRouter().pushController(RouterTransaction.with(new NavigationDemoController(0, true))
+                getRouter().pushController(RouterTransaction.with(new NavigationDemoController(0, DisplayUpMode.SHOW_FOR_CHILDREN_ONLY))
                         .pushChangeHandler(new FadeChangeHandler())
                         .popChangeHandler(new FadeChangeHandler())
                         .tag(NavigationDemoController.TAG_UP_TRANSACTION)
@@ -159,7 +160,7 @@ public class HomeController extends BaseController {
                         .popChangeHandler(new FadeChangeHandler()));
                 break;
             case OVERLAY:
-                getChildRouter(overlayRoot, null)
+                getChildRouter(overlayRoot)
                         .setPopsLastView(true)
                         .setRoot(RouterTransaction.with(new OverlayController("I'm an overlay!"))
                                 .pushChangeHandler(new FadeChangeHandler())

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/MasterDetailListController.java

@@ -91,7 +91,7 @@ public class MasterDetailListController extends BaseController {
         ChildController controller = new ChildController(model.detail, model.backgroundColor, true);
 
         if (twoPaneView) {
-            getChildRouter(detailContainer, null).setRoot(RouterTransaction.with(controller));
+            getChildRouter(detailContainer).setRoot(RouterTransaction.with(controller));
         } else {
             getRouter().pushController(RouterTransaction.with(controller)
                     .pushChangeHandler(new HorizontalChangeHandler())

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/MultipleChildRouterController.java

@@ -8,6 +8,7 @@ import android.view.ViewGroup;
 import com.bluelinelabs.conductor.Router;
 import com.bluelinelabs.conductor.RouterTransaction;
 import com.bluelinelabs.conductor.demo.R;
+import com.bluelinelabs.conductor.demo.controllers.NavigationDemoController.DisplayUpMode;
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController;
 
 import butterknife.BindViews;
@@ -26,9 +27,9 @@ public class MultipleChildRouterController extends BaseController {
         super.onViewBound(view);
 
         for (ViewGroup childContainer : childContainers) {
-            Router childRouter = getChildRouter(childContainer, null).setPopsLastView(false);
+            Router childRouter = getChildRouter(childContainer).setPopsLastView(false);
             if (!childRouter.hasRootController()) {
-                childRouter.setRoot(RouterTransaction.with(new NavigationDemoController(0, false)));
+                childRouter.setRoot(RouterTransaction.with(new NavigationDemoController(0, DisplayUpMode.HIDE)));
             }
         }
     }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/NavigationDemoController.java

@@ -7,6 +7,8 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+import com.bluelinelabs.conductor.ControllerChangeType;
 import com.bluelinelabs.conductor.RouterTransaction;
 import com.bluelinelabs.conductor.changehandler.HorizontalChangeHandler;
 import com.bluelinelabs.conductor.demo.R;
@@ -19,27 +21,42 @@ import butterknife.OnClick;
 
 public class NavigationDemoController extends BaseController {
 
+    public enum DisplayUpMode {
+        SHOW,
+        SHOW_FOR_CHILDREN_ONLY,
+        HIDE;
+
+        private DisplayUpMode getDisplayUpModeForChild() {
+            switch (this) {
+                case HIDE:
+                    return HIDE;
+                default:
+                    return SHOW;
+            }
+        }
+    }
+
     public static final String TAG_UP_TRANSACTION = "NavigationDemoController.up";
 
     private static final String KEY_INDEX = "NavigationDemoController.index";
-    private static final String KEY_DISPLAY_UP = "NavigationDemoController.displayUp";
+    private static final String KEY_DISPLAY_UP_MODE = "NavigationDemoController.displayUpMode";
 
     @BindView(R.id.tv_title) TextView tvTitle;
 
     private int index;
-    private boolean displayUp;
+    private DisplayUpMode displayUpMode;
 
-    public NavigationDemoController(int index, boolean displayUpButton) {
+    public NavigationDemoController(int index, DisplayUpMode displayUpMode) {
         this(new BundleBuilder(new Bundle())
                 .putInt(KEY_INDEX, index)
-                .putBoolean(KEY_DISPLAY_UP, displayUpButton)
+                .putInt(KEY_DISPLAY_UP_MODE, displayUpMode.ordinal())
                 .build());
     }
 
     public NavigationDemoController(Bundle args) {
         super(args);
         index = args.getInt(KEY_INDEX);
-        displayUp = args.getBoolean(KEY_DISPLAY_UP);
+        displayUpMode = DisplayUpMode.values()[args.getInt(KEY_DISPLAY_UP_MODE)];
     }
 
     @NonNull
@@ -52,7 +69,7 @@ public class NavigationDemoController extends BaseController {
     protected void onViewBound(@NonNull View view) {
         super.onViewBound(view);
 
-        if (!displayUp) {
+        if (displayUpMode != DisplayUpMode.SHOW) {
             view.findViewById(R.id.btn_up).setVisibility(View.GONE);
         }
 
@@ -60,13 +77,36 @@ public class NavigationDemoController extends BaseController {
         tvTitle.setText(getResources().getString(R.string.navigation_title, index));
     }
 
+    @Override
+    protected void onChangeEnded(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
+        super.onChangeEnded(changeHandler, changeType);
+
+        setButtonsEnabled(true);
+    }
+
+    @Override
+    protected void onChangeStarted(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
+        super.onChangeStarted(changeHandler, changeType);
+
+        setButtonsEnabled(false);
+    }
+
     @Override
     protected String getTitle() {
         return "Navigation Demos";
     }
 
+    private void setButtonsEnabled(boolean enabled) {
+        final View view = getView();
+        if (view != null) {
+            view.findViewById(R.id.btn_next).setEnabled(enabled);
+            view.findViewById(R.id.btn_up).setEnabled(enabled);
+            view.findViewById(R.id.btn_pop_to_root).setEnabled(enabled);
+        }
+    }
+
     @OnClick(R.id.btn_next) void onNextClicked() {
-        getRouter().pushController(RouterTransaction.with(new NavigationDemoController(index + 1, displayUp))
+        getRouter().pushController(RouterTransaction.with(new NavigationDemoController(index + 1, displayUpMode.getDisplayUpModeForChild()))
                 .pushChangeHandler(new HorizontalChangeHandler())
                 .popChangeHandler(new HorizontalChangeHandler()));
     }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/PagerController.java

@@ -12,6 +12,8 @@ import com.bluelinelabs.conductor.demo.R;
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController;
 import com.bluelinelabs.conductor.support.ControllerPagerAdapter;
 
+import java.util.Locale;
+
 import butterknife.BindView;
 
 public class PagerController extends BaseController {
@@ -27,7 +29,7 @@ public class PagerController extends BaseController {
         pagerAdapter = new ControllerPagerAdapter(this, false) {
             @Override
             public Controller getItem(int position) {
-                return new ChildController(String.format("Child #%d (Swipe to see more)", position), PAGE_COLORS[position], true);
+                return new ChildController(String.format(Locale.getDefault(), "Child #%d (Swipe to see more)", position), PAGE_COLORS[position], true);
             }
 
             @Override
@@ -50,7 +52,7 @@ public class PagerController extends BaseController {
     }
 
     @Override
-    protected void onDestroyView(View view) {
+    protected void onDestroyView(@NonNull View view) {
         viewPager.setAdapter(null);
         super.onDestroyView(view);
     }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/ParentController.java

@@ -16,10 +16,13 @@ import com.bluelinelabs.conductor.demo.R;
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController;
 import com.bluelinelabs.conductor.demo.util.ColorUtil;
 
+import java.util.List;
+
 public class ParentController extends BaseController {
 
     private static final int NUMBER_OF_CHILDREN = 5;
     private boolean finishing;
+    private boolean hasShownAll;
 
     @NonNull
     @Override
@@ -39,7 +42,7 @@ public class ParentController extends BaseController {
     private void addChild(final int index) {
         @IdRes final int frameId = getResources().getIdentifier("child_content_" + (index + 1), "id", getActivity().getPackageName());
         final ViewGroup container = (ViewGroup)getView().findViewById(frameId);
-        final Router childRouter = getChildRouter(container, null).setPopsLastView(true);
+        final Router childRouter = getChildRouter(container).setPopsLastView(true);
 
         if (!childRouter.hasRootController()) {
             ChildController childController = new ChildController("Child Controller #" + index, ColorUtil.getMaterialColor(getResources(), index), false);
@@ -47,8 +50,12 @@ public class ParentController extends BaseController {
             childController.addLifecycleListener(new LifecycleListener() {
                 @Override
                 public void onChangeEnd(@NonNull Controller controller, @NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
-                    if (changeType == ControllerChangeType.PUSH_ENTER && index < NUMBER_OF_CHILDREN - 1) {
-                        addChild(index + 1);
+                    if (changeType == ControllerChangeType.PUSH_ENTER && !hasShownAll) {
+                        if (index < NUMBER_OF_CHILDREN - 1) {
+                            addChild(index + 1);
+                        } else {
+                            hasShownAll = true;
+                        }
                     } else if (changeType == ControllerChangeType.POP_EXIT) {
                         if (index > 0) {
                             removeChild(index - 1);
@@ -66,16 +73,27 @@ public class ParentController extends BaseController {
     }
 
     private void removeChild(int index) {
-        removeChildRouter(getChildRouters().get(index));
+        List<Router> childRouters = getChildRouters();
+        if (index < childRouters.size()) {
+            removeChildRouter(childRouters.get(index));
+        }
     }
 
     @Override
     public boolean handleBack() {
-        if (!finishing) {
+        int childControllers = 0;
+        for (Router childRouter : getChildRouters()) {
+            if (childRouter.hasRootController()) {
+                childControllers++;
+            }
+        }
+
+        if (childControllers != NUMBER_OF_CHILDREN || finishing) {
+            return true;
+        } else {
             finishing = true;
             return super.handleBack();
         }
-        return true;
     }
 
     @Override

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/RxLifecycleController.java

@@ -92,7 +92,7 @@ public class RxLifecycleController extends BaseController {
     }
 
     @Override
-    protected void onDestroyView(View view) {
+    protected void onDestroyView(@NonNull View view) {
         super.onDestroyView(view);
 
         Log.i(TAG, "onDestroyView() called");

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/TransitionDemoController.java

@@ -140,11 +140,10 @@ public class TransitionDemoController extends BaseController {
 
     public static RouterTransaction getRouterTransaction(int index, Controller fromController) {
         TransitionDemoController toController = new TransitionDemoController(index);
-        ControllerChangeHandler changeHandler = toController.getChangeHandler(fromController);
 
         return RouterTransaction.with(toController)
-                .pushChangeHandler(changeHandler)
-                .popChangeHandler(changeHandler);
+                .pushChangeHandler(toController.getChangeHandler(fromController))
+                .popChangeHandler(toController.getChangeHandler(fromController));
     }
 
 }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/base/ButterKnifeController.java

@@ -34,9 +34,10 @@ public abstract class ButterKnifeController extends RxController {
     protected void onViewBound(@NonNull View view) { }
 
     @Override
-    protected void onDestroyView(View view) {
+    protected void onDestroyView(@NonNull View view) {
         super.onDestroyView(view);
         unbinder.unbind();
+        unbinder = null;
     }
 
 }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/base/RefWatchingController.java

@@ -1,7 +1,10 @@
 package com.bluelinelabs.conductor.demo.controllers.base;
 
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+import com.bluelinelabs.conductor.ControllerChangeType;
 import com.bluelinelabs.conductor.demo.DemoApplication;
 
 public abstract class RefWatchingController extends ButterKnifeController {
@@ -11,10 +14,24 @@ public abstract class RefWatchingController extends ButterKnifeController {
         super(args);
     }
 
+    private boolean hasExited;
+
     @Override
     public void onDestroy() {
         super.onDestroy();
-        DemoApplication.refWatcher.watch(this);
+
+        if (hasExited) {
+            DemoApplication.refWatcher.watch(this);
+        }
     }
 
+    @Override
+    protected void onChangeEnded(@NonNull ControllerChangeHandler changeHandler, @NonNull ControllerChangeType changeType) {
+        super.onChangeEnded(changeHandler, changeType);
+
+        hasExited = !changeType.isEnter;
+        if (isDestroyed()) {
+            DemoApplication.refWatcher.watch(this);
+        }
+    }
 }

demo/src/main/res/values/material_colors.xml

@@ -1,23 +1,23 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <array name="mdcolor_300">
-        <item name="red_300" type="color">@color/red_300</item>
-        <item name="light_green_300" type="color">@color/light_green_300</item>
-        <item name="teal_300" type="color">@color/teal_300</item>
-        <item name="pink_300" type="color">@color/pink_300</item>
-        <item name="brown_300" type="color">@color/brown_300</item>
-        <item name="purple_300" type="color">@color/purple_300</item>
-        <item name="lime_300" type="color">@color/lime_300</item>
-        <item name="blue_grey_300" type="color">@color/blue_grey_300</item>
-        <item name="deep_purple_300" type="color">@color/deep_purple_300</item>
-        <item name="green_300" type="color">@color/green_300</item>
-        <item name="indigo_300" type="color">@color/indigo_300</item>
-        <item name="yellow_300" type="color">@color/yellow_300</item>
-        <item name="blue_300" type="color">@color/blue_300</item>
-        <item name="orange_300" type="color">@color/orange_300</item>
-        <item name="light_blue_300" type="color">@color/light_blue_300</item>
-        <item name="deep_orange_300" type="color">@color/deep_orange_300</item>
-        <item name="cyan_300" type="color">@color/cyan_300</item>
-        <item name="grey_300" type="color">@color/grey_300</item>
+        <item name="md_red_300" type="color">@color/red_300</item>
+        <item name="md_light_green_300" type="color">@color/light_green_300</item>
+        <item name="md_teal_300" type="color">@color/teal_300</item>
+        <item name="md_pink_300" type="color">@color/pink_300</item>
+        <item name="md_brown_300" type="color">@color/brown_300</item>
+        <item name="md_purple_300" type="color">@color/purple_300</item>
+        <item name="md_lime_300" type="color">@color/lime_300</item>
+        <item name="md_blue_grey_300" type="color">@color/blue_grey_300</item>
+        <item name="md_deep_purple_300" type="color">@color/deep_purple_300</item>
+        <item name="md_green_300" type="color">@color/green_300</item>
+        <item name="md_indigo_300" type="color">@color/indigo_300</item>
+        <item name="md_yellow_300" type="color">@color/yellow_300</item>
+        <item name="md_blue_300" type="color">@color/blue_300</item>
+        <item name="md_orange_300" type="color">@color/orange_300</item>
+        <item name="md_light_blue_300" type="color">@color/light_blue_300</item>
+        <item name="md_deep_orange_300" type="color">@color/deep_orange_300</item>
+        <item name="md_cyan_300" type="color">@color/cyan_300</item>
+        <item name="md_grey_300" type="color">@color/grey_300</item>
     </array>
 </resources>

dependencies.gradle

@@ -14,12 +14,13 @@ ext {
 
     picasso = 'com.squareup.picasso:picasso:2.5.2'
 
-    leakCanary = 'com.squareup.leakcanary:leakcanary-android:1.4-beta2'
-    leakCanaryNoOp = 'com.squareup.leakcanary:leakcanary-android-no-op:1.4-beta2'
+    leakCanary = 'com.squareup.leakcanary:leakcanary-android:1.4'
+    leakCanaryNoOp = 'com.squareup.leakcanary:leakcanary-android-no-op:1.4'
 
-    rxJava = 'io.reactivex:rxjava:1.1.0'
-    rxAndroid = 'io.reactivex:rxandroid:1.1.0'
-    rxLifecycle = 'com.trello:rxlifecycle:0.6.0'
+    rxJava = 'io.reactivex:rxjava:1.2.0'
+    rxAndroid = 'io.reactivex:rxandroid:1.2.1'
+    rxLifecycle = 'com.trello:rxlifecycle:0.8.0'
+    rxLifecycleAndroid = 'com.trello:rxlifecycle-android:0.8.0'
 
     junit = 'junit:junit:4.11'
     roboelectric = 'org.robolectric:robolectric:3.0'

gradle.properties

@@ -1,4 +1,4 @@
-VERSION_NAME=2.0.1-SNAPSHOT
+VERSION_NAME=2.0.5-SNAPSHOT
 VERSION_CODE=2
 GROUP=com.bluelinelabs
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Tue Jan 19 22:43:12 CST 2016
+#Mon Sep 05 10:45:48 CDT 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.10-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-all.zip