Update version to 5.1.1

Fix NPE when localStackCopy.size() == 0 and FragmentFactory is used

build.gradle

@@ -6,7 +6,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.3.0-alpha12'
+        classpath 'com.android.tools.build:gradle:3.5.0'
 
         // For the library uploading to the Bintray
         classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.1'

gradle.properties

@@ -12,7 +12,8 @@
 # Default value: -Xmx10248m -XX:MaxPermSize=256m
 # org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
 org.gradle.jvmargs=-Xmx4096m -XX:MaxPermSize=1024m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8
-
+android.enableJetifier=true
+android.useAndroidX=true
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit
 # http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Thu Sep 27 15:42:22 MSK 2018
+#Fri Jan 25 22:04:15 MSK 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.10.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip

library/build.gradle

@@ -8,6 +8,7 @@ targetCompatibility = JavaVersion.VERSION_1_7
 dependencies {
     compileOnly project(':stub-android')
     compileOnly 'com.google.android:android:4.1.1.4'
+    implementation "org.jetbrains:annotations:16.0.3"
 }
 
 ext {
@@ -16,7 +17,7 @@ ext {
     bintrayName = 'cicerone'
     publishedGroupId = 'ru.terrakok.cicerone'
     artifact = 'cicerone'
-    libraryVersion = '4.0.2'
+    libraryVersion = '5.1.1'
     gitUrl = 'https://github.com/terrakok/Cicerone'
     allLicenses = ['MIT']
 }
@@ -24,7 +25,7 @@ ext {
 // Configuration of the library uploading to the Bintray
 // Note: Call 'bintrayUpload' task (it will execute 'install' task first)
 // I try to include as little properties as possible in these files
-project.archivesBaseName ='cicerone' // to fix that project name different from artifact name
+project.archivesBaseName = 'cicerone' // to fix that project name different from artifact name
 apply from: 'androidmaven.gradle'
 apply from: 'bintray.gradle'
 

library/src/main/java/ru/terrakok/cicerone/BaseRouter.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+
 import ru.terrakok.cicerone.commands.Command;
 
 /**
@@ -17,6 +19,7 @@ public abstract class BaseRouter {
         this.commandBuffer = new CommandBuffer();
     }
 
+    @NotNull
     CommandBuffer getCommandBuffer() {
         return commandBuffer;
     }
@@ -26,7 +29,7 @@ public abstract class BaseRouter {
      *
      * @param commands navigation command array to execute
      */
-    protected void executeCommands(Command... commands) {
+    protected void executeCommands(@NotNull Command... commands) {
         commandBuffer.executeCommands(commands);
     }
 }

library/src/main/java/ru/terrakok/cicerone/Cicerone.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * Cicerone is the holder for other library components.
  * To use it, instantiate it using one of the {@link #create()} methods.
@@ -15,14 +17,16 @@ package ru.terrakok.cicerone;
 public class Cicerone<T extends BaseRouter> {
     private T router;
 
-    private Cicerone(T router) {
+    private Cicerone(@NotNull T router) {
         this.router = router;
     }
 
+    @NotNull
     public NavigatorHolder getNavigatorHolder() {
         return router.getCommandBuffer();
     }
 
+    @NotNull
     public T getRouter() {
         return router;
     }
@@ -30,6 +34,7 @@ public class Cicerone<T extends BaseRouter> {
     /**
      * Creates the Cicerone instance with the default {@link Router router}
      */
+    @NotNull
     public static Cicerone<Router> create() {
         return create(new Router());
     }
@@ -38,7 +43,8 @@ public class Cicerone<T extends BaseRouter> {
      * Creates the Cicerone instance with the custom router.
      * @param customRouter the custom router extending {@link BaseRouter}
      */
-    public static <T extends BaseRouter> Cicerone<T> create(T customRouter) {
+    @NotNull
+    public static <T extends BaseRouter> Cicerone<T> create(@NotNull T customRouter) {
         return new Cicerone<>(customRouter);
     }
 }

library/src/main/java/ru/terrakok/cicerone/CommandBuffer.java

@@ -4,6 +4,9 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 import java.util.LinkedList;
 import java.util.Queue;
 
@@ -18,7 +21,7 @@ class CommandBuffer implements NavigatorHolder {
     private Queue<Command[]> pendingCommands = new LinkedList<>();
 
     @Override
-    public void setNavigator(Navigator navigator) {
+    public void setNavigator(@Nullable Navigator navigator) {
         this.navigator = navigator;
         while (!pendingCommands.isEmpty()) {
             if (navigator != null) {
@@ -37,7 +40,7 @@ class CommandBuffer implements NavigatorHolder {
      * Else puts it to the pending commands queue to pass it later.
      * @param commands navigation command array
      */
-    void executeCommands(Command[] commands) {
+    void executeCommands(@NotNull Command[] commands) {
         if (navigator != null) {
             navigator.applyCommands(commands);
         } else {

library/src/main/java/ru/terrakok/cicerone/Navigator.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+
 import ru.terrakok.cicerone.commands.Command;
 
 /**
@@ -17,5 +19,5 @@ public interface Navigator {
      *
      * @param commands the navigation command array to apply per single transaction
      */
-    void applyCommands(Command[] commands);
+    void applyCommands(@NotNull Command[] commands);
 }

library/src/main/java/ru/terrakok/cicerone/NavigatorHolder.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * Navigator holder interface.
  * Use it to connect a {@link Navigator} to the {@link Cicerone}.
@@ -15,7 +17,7 @@ public interface NavigatorHolder {
      *
      * @param navigator new active Navigator
      */
-    void setNavigator(Navigator navigator);
+    void setNavigator(@NotNull Navigator navigator);
 
     /**
      * Remove the current Navigator and stop receive commands.

library/src/main/java/ru/terrakok/cicerone/Router.java

@@ -4,6 +4,9 @@
 
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 import ru.terrakok.cicerone.commands.Back;
 import ru.terrakok.cicerone.commands.BackTo;
 import ru.terrakok.cicerone.commands.Command;
@@ -27,7 +30,7 @@ public class Router extends BaseRouter {
      *
      * @param screen screen
      */
-    public void navigateTo(Screen screen) {
+    public void navigateTo(@NotNull Screen screen) {
         executeCommands(new Forward(screen));
     }
 
@@ -36,7 +39,7 @@ public class Router extends BaseRouter {
      *
      * @param screen screen
      */
-    public void newRootScreen(Screen screen) {
+    public void newRootScreen(@NotNull Screen screen) {
         executeCommands(
                 new BackTo(null),
                 new Replace(screen)
@@ -51,7 +54,7 @@ public class Router extends BaseRouter {
      *
      * @param screen screen
      */
-    public void replaceScreen(Screen screen) {
+    public void replaceScreen(@NotNull Screen screen) {
         executeCommands(new Replace(screen));
     }
 
@@ -62,7 +65,7 @@ public class Router extends BaseRouter {
      *
      * @param screen screen
      */
-    public void backTo(Screen screen) {
+    public void backTo(@Nullable Screen screen) {
         executeCommands(new BackTo(screen));
     }
 
@@ -70,7 +73,7 @@ public class Router extends BaseRouter {
      * Opens several screens inside single transaction.
      * @param screens
      */
-    public void newChain(Screen... screens) {
+    public void newChain(@NotNull Screen... screens) {
         Command[] commands = new Command[screens.length];
         for (int i = 0; i < commands.length; i++) {
             commands[i] = new Forward(screens[i]);
@@ -82,7 +85,7 @@ public class Router extends BaseRouter {
      * Clear current stack and open several screens inside single transaction.
      * @param screens
      */
-    public void newRootChain(Screen... screens) {
+    public void newRootChain(@NotNull Screen... screens) {
         Command[] commands = new Command[screens.length + 1];
         commands[0] = new BackTo(null);
         if (screens.length > 0) {

library/src/main/java/ru/terrakok/cicerone/Screen.java

@@ -1,11 +1,14 @@
 package ru.terrakok.cicerone;
 
+import org.jetbrains.annotations.NotNull;
+
 /**
  * Screen is class for description application screen.
  */
 public abstract class Screen {
     protected String screenKey = getClass().getCanonicalName();
 
+    @NotNull
     public String getScreenKey() {
         return screenKey;
     }

library/src/main/java/ru/terrakok/cicerone/android/pure/AppNavigator.java

@@ -6,16 +6,13 @@ import android.app.FragmentManager;
 import android.app.FragmentTransaction;
 import android.content.Intent;
 import android.os.Bundle;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import ru.terrakok.cicerone.Navigator;
+import ru.terrakok.cicerone.commands.*;
 
 import java.util.LinkedList;
 
-import ru.terrakok.cicerone.Navigator;
-import ru.terrakok.cicerone.commands.Back;
-import ru.terrakok.cicerone.commands.BackTo;
-import ru.terrakok.cicerone.commands.Command;
-import ru.terrakok.cicerone.commands.Forward;
-import ru.terrakok.cicerone.commands.Replace;
-
 /**
  * Navigator implementation for launch fragments and activities.<br>
  * Feature {@link BackTo} works only for fragments.<br>
@@ -23,30 +20,34 @@ import ru.terrakok.cicerone.commands.Replace;
  */
 public class AppNavigator implements Navigator {
 
-    private final Activity activity;
-    private final FragmentManager fragmentManager;
-    private final int containerId;
-    private LinkedList<String> localStackCopy;
+    protected final Activity activity;
+    protected final FragmentManager fragmentManager;
+    protected final int containerId;
+    protected LinkedList<String> localStackCopy;
 
-    public AppNavigator(Activity activity, int containerId) {
+    public AppNavigator(@NotNull Activity activity, int containerId) {
         this(activity, activity.getFragmentManager(), containerId);
     }
 
-    public AppNavigator(Activity activity, FragmentManager fragmentManager, int containerId) {
+    public AppNavigator(@NotNull Activity activity, @NotNull FragmentManager fragmentManager, int containerId) {
         this.activity = activity;
         this.fragmentManager = fragmentManager;
         this.containerId = containerId;
     }
 
     @Override
-    public void applyCommands(Command[] commands) {
+    public void applyCommands(@NotNull Command[] commands) {
         fragmentManager.executePendingTransactions();
 
         //copy stack before apply commands
         copyStackToLocal();
 
         for (Command command : commands) {
-            applyCommand(command);
+            try {
+                applyCommand(command);
+            } catch (RuntimeException e) {
+                errorOnApplyCommand(command, e);
+            }
         }
     }
 
@@ -64,7 +65,7 @@ public class AppNavigator implements Navigator {
      *
      * @param command the navigation command to apply
      */
-    protected void applyCommand(Command command) {
+    protected void applyCommand(@NotNull Command command) {
         if (command instanceof Forward) {
             activityForward((Forward) command);
         } else if (command instanceof Replace) {
@@ -77,7 +78,7 @@ public class AppNavigator implements Navigator {
     }
 
 
-    protected void activityForward(Forward command) {
+    protected void activityForward(@NotNull Forward command) {
         AppScreen screen = (AppScreen) command.getScreen();
         Intent activityIntent = screen.getActivityIntent(activity);
 
@@ -90,7 +91,7 @@ public class AppNavigator implements Navigator {
         }
     }
 
-    protected void fragmentForward(Forward command) {
+    protected void fragmentForward(@NotNull Forward command) {
         AppScreen screen = (AppScreen) command.getScreen();
         Fragment fragment = createFragment(screen);
 
@@ -123,7 +124,7 @@ public class AppNavigator implements Navigator {
         activity.finish();
     }
 
-    protected void activityReplace(Replace command) {
+    protected void activityReplace(@NotNull Replace command) {
         AppScreen screen = (AppScreen) command.getScreen();
         Intent activityIntent = screen.getActivityIntent(activity);
 
@@ -137,7 +138,7 @@ public class AppNavigator implements Navigator {
         }
     }
 
-    protected void fragmentReplace(Replace command) {
+    protected void fragmentReplace(@NotNull Replace command) {
         AppScreen screen = (AppScreen) command.getScreen();
         Fragment fragment = createFragment(screen);
 
@@ -179,7 +180,7 @@ public class AppNavigator implements Navigator {
     /**
      * Performs {@link BackTo} command transition
      */
-    protected void backTo(BackTo command) {
+    protected void backTo(@NotNull BackTo command) {
         if (command.getScreen() == null) {
             backToRoot();
         } else {
@@ -213,10 +214,10 @@ public class AppNavigator implements Navigator {
      * @param nextFragment        next screen fragment
      * @param fragmentTransaction fragment transaction
      */
-    protected void setupFragmentTransaction(Command command,
-                                            Fragment currentFragment,
-                                            Fragment nextFragment,
-                                            FragmentTransaction fragmentTransaction) {
+    protected void setupFragmentTransaction(@NotNull Command command,
+                                            @Nullable Fragment currentFragment,
+                                            @Nullable Fragment nextFragment,
+                                            @NotNull FragmentTransaction fragmentTransaction) {
     }
 
     /**
@@ -226,11 +227,14 @@ public class AppNavigator implements Navigator {
      * @param activityIntent activity intent
      * @return transition options
      */
-    protected Bundle createStartActivityOptions(Command command, Intent activityIntent) {
+    @Nullable
+    protected Bundle createStartActivityOptions(@NotNull Command command, @NotNull Intent activityIntent) {
         return null;
     }
 
-    private void checkAndStartActivity(AppScreen screen, Intent activityIntent, Bundle options) {
+    private void checkAndStartActivity(@NotNull AppScreen screen,
+                                       @NotNull Intent activityIntent,
+                                       @Nullable Bundle options) {
         // Check if we can start activity
         if (activityIntent.resolveActivity(activity.getPackageManager()) != null) {
             activity.startActivity(activityIntent, options);
@@ -245,7 +249,7 @@ public class AppNavigator implements Navigator {
      * @param screen         screen
      * @param activityIntent intent passed to start Activity for the {@code screenKey}
      */
-    protected void unexistingActivity(AppScreen screen, Intent activityIntent) {
+    protected void unexistingActivity(@NotNull AppScreen screen, @NotNull Intent activityIntent) {
         // Do nothing by default
     }
 
@@ -255,11 +259,13 @@ public class AppNavigator implements Navigator {
      * @param screen screen
      * @return instantiated fragment for the passed screen
      */
-    protected Fragment createFragment(AppScreen screen) {
+    @Nullable
+    protected Fragment createFragment(@NotNull AppScreen screen) {
         Fragment fragment = screen.getFragment();
 
         if (fragment == null) {
             errorWhileCreatingScreen(screen);
+            throw new RuntimeException("Can't create a screen: " + screen.getScreenKey());
         }
         return fragment;
     }
@@ -270,11 +276,29 @@ public class AppNavigator implements Navigator {
      *
      * @param screen screen
      */
-    protected void backToUnexisting(AppScreen screen) {
+    protected void backToUnexisting(@NotNull AppScreen screen) {
         backToRoot();
     }
 
-    protected void errorWhileCreatingScreen(AppScreen screen) {
-        throw new RuntimeException("Can't create a screen: " + screen.getScreenKey());
+    /**
+     * Called when we tried to create new intent or fragment but didn't receive them.
+     *
+     * @param screen screen
+     */
+    protected void errorWhileCreatingScreen(@NotNull AppScreen screen) {
+        // Do nothing by default
+    }
+
+    /**
+     * Override this method if you want to handle apply command error.
+     *
+     * @param command command
+     * @param error error
+     */
+    protected void errorOnApplyCommand(
+            @NotNull Command command,
+            @NotNull RuntimeException error
+    ) {
+        throw error;
     }
 }

library/src/main/java/ru/terrakok/cicerone/android/pure/AppScreen.java

@@ -4,6 +4,8 @@ import android.app.Fragment;
 import android.content.Context;
 import android.content.Intent;
 
+import org.jetbrains.annotations.Nullable;
+
 import ru.terrakok.cicerone.Screen;
 
 /**
@@ -13,10 +15,12 @@ import ru.terrakok.cicerone.Screen;
  */
 public abstract class AppScreen extends Screen {
 
+    @Nullable
     public Fragment getFragment() {
         return null;
     }
 
+    @Nullable
     public Intent getActivityIntent(Context context) {
         return null;
     }

library/src/main/java/ru/terrakok/cicerone/android/support/FragmentParams.java

@@ -0,0 +1,36 @@
+package ru.terrakok.cicerone.android.support;
+
+import android.os.Bundle;
+
+import androidx.fragment.app.Fragment;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public final class FragmentParams {
+
+    @NotNull
+    private final Class<? extends Fragment> fragmentClass;
+    @Nullable
+    private final Bundle arguments;
+
+    @NotNull
+    public final Class<? extends Fragment> getFragmentClass() {
+        return this.fragmentClass;
+    }
+
+    @Nullable
+    public final Bundle getArguments() {
+        return this.arguments;
+    }
+
+    public FragmentParams(@NotNull Class<? extends Fragment> fragmentClass, @Nullable Bundle arguments) {
+        this.fragmentClass = fragmentClass;
+        this.arguments = arguments;
+    }
+
+    public FragmentParams(@NotNull Class<? extends Fragment> fragmentClass) {
+        this.fragmentClass = fragmentClass;
+        this.arguments = null;
+    }
+}

library/src/main/java/ru/terrakok/cicerone/android/support/SupportAppNavigator.java

@@ -3,10 +3,14 @@ package ru.terrakok.cicerone.android.support;
 import android.app.Activity;
 import android.content.Intent;
 import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentActivity;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentTransaction;
+
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.LinkedList;
 
@@ -24,30 +28,34 @@ import ru.terrakok.cicerone.commands.Replace;
  */
 public class SupportAppNavigator implements Navigator {
 
-    private final Activity activity;
-    private final FragmentManager fragmentManager;
-    private final int containerId;
-    private LinkedList<String> localStackCopy;
+    protected final Activity activity;
+    protected final FragmentManager fragmentManager;
+    protected final int containerId;
+    protected LinkedList<String> localStackCopy;
 
-    public SupportAppNavigator(FragmentActivity activity, int containerId) {
+    public SupportAppNavigator(@NotNull FragmentActivity activity, int containerId) {
         this(activity, activity.getSupportFragmentManager(), containerId);
     }
 
-    public SupportAppNavigator(FragmentActivity activity, FragmentManager fragmentManager, int containerId) {
+    public SupportAppNavigator(@NotNull FragmentActivity activity, @NotNull FragmentManager fragmentManager, int containerId) {
         this.activity = activity;
         this.fragmentManager = fragmentManager;
         this.containerId = containerId;
     }
 
     @Override
-    public void applyCommands(Command[] commands) {
+    public void applyCommands(@NotNull Command[] commands) {
         fragmentManager.executePendingTransactions();
 
         //copy stack before apply commands
         copyStackToLocal();
 
         for (Command command : commands) {
-            applyCommand(command);
+            try {
+                applyCommand(command);
+            } catch (RuntimeException e) {
+                errorOnApplyCommand(command, e);
+            }
         }
     }
 
@@ -65,7 +73,7 @@ public class SupportAppNavigator implements Navigator {
      *
      * @param command the navigation command to apply
      */
-    protected void applyCommand(Command command) {
+    protected void applyCommand(@NotNull Command command) {
         if (command instanceof Forward) {
             activityForward((Forward) command);
         } else if (command instanceof Replace) {
@@ -78,7 +86,7 @@ public class SupportAppNavigator implements Navigator {
     }
 
 
-    protected void activityForward(Forward command) {
+    protected void activityForward(@NotNull Forward command) {
         SupportAppScreen screen = (SupportAppScreen) command.getScreen();
         Intent activityIntent = screen.getActivityIntent(activity);
 
@@ -91,24 +99,13 @@ public class SupportAppNavigator implements Navigator {
         }
     }
 
-    protected void fragmentForward(Forward command) {
+    protected void fragmentForward(@NotNull Forward command) {
         SupportAppScreen screen = (SupportAppScreen) command.getScreen();
-        Fragment fragment = createFragment(screen);
 
-        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
+        FragmentParams fragmentParams = screen.getFragmentParams();
+        Fragment fragment = fragmentParams == null ? createFragment(screen) : null;
 
-        setupFragmentTransaction(
-                command,
-                fragmentManager.findFragmentById(containerId),
-                fragment,
-                fragmentTransaction
-        );
-
-        fragmentTransaction
-                .replace(containerId, fragment)
-                .addToBackStack(screen.getScreenKey())
-                .commit();
-        localStackCopy.add(screen.getScreenKey());
+        forwardFragmentInternal(command, screen, fragmentParams, fragment);
     }
 
     protected void fragmentBack() {
@@ -124,7 +121,7 @@ public class SupportAppNavigator implements Navigator {
         activity.finish();
     }
 
-    protected void activityReplace(Replace command) {
+    protected void activityReplace(@NotNull Replace command) {
         SupportAppScreen screen = (SupportAppScreen) command.getScreen();
         Intent activityIntent = screen.getActivityIntent(activity);
 
@@ -138,28 +135,17 @@ public class SupportAppNavigator implements Navigator {
         }
     }
 
-    protected void fragmentReplace(Replace command) {
+    protected void fragmentReplace(@NotNull Replace command) {
         SupportAppScreen screen = (SupportAppScreen) command.getScreen();
-        Fragment fragment = createFragment(screen);
+
+        FragmentParams fragmentParams = screen.getFragmentParams();
+        Fragment fragment = fragmentParams == null ? createFragment(screen) : null;
 
         if (localStackCopy.size() > 0) {
             fragmentManager.popBackStack();
             localStackCopy.removeLast();
 
-            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
-
-            setupFragmentTransaction(
-                    command,
-                    fragmentManager.findFragmentById(containerId),
-                    fragment,
-                    fragmentTransaction
-            );
-
-            fragmentTransaction
-                    .replace(containerId, fragment)
-                    .addToBackStack(screen.getScreenKey())
-                    .commit();
-            localStackCopy.add(screen.getScreenKey());
+            forwardFragmentInternal(command, screen, fragmentParams, fragment);
 
         } else {
             FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
@@ -171,16 +157,60 @@ public class SupportAppNavigator implements Navigator {
                     fragmentTransaction
             );
 
-            fragmentTransaction
-                    .replace(containerId, fragment)
-                    .commit();
+            replaceFragmentInternal(fragmentTransaction, screen, fragmentParams, fragment);
+
+            fragmentTransaction.commit();
+        }
+    }
+
+    private void forwardFragmentInternal(
+            @NotNull Command command,
+            @NotNull SupportAppScreen screen,
+            @Nullable FragmentParams fragmentParams,
+            @Nullable Fragment fragment
+    ) {
+        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
+
+        setupFragmentTransaction(
+                command,
+                fragmentManager.findFragmentById(containerId),
+                fragment,
+                fragmentTransaction
+        );
+
+        replaceFragmentInternal(fragmentTransaction, screen, fragmentParams, fragment);
+
+        fragmentTransaction
+                .addToBackStack(screen.getScreenKey())
+                .commit();
+
+        localStackCopy.add(screen.getScreenKey());
+    }
+
+    private void replaceFragmentInternal(
+            @NotNull FragmentTransaction transaction,
+            @NotNull SupportAppScreen screen,
+            @Nullable FragmentParams params,
+            @Nullable Fragment fragment
+    ) {
+        if (params != null) {
+            transaction.replace(
+                    containerId,
+                    params.getFragmentClass(),
+                    params.getArguments()
+            );
+        } else if (fragment != null) {
+            transaction.replace(containerId, fragment);
+        } else {
+            throw new IllegalArgumentException("Either 'params' or 'fragment' shouldn't " +
+                    "be null for " + screen.getScreenKey());
         }
     }
 
     /**
      * Performs {@link BackTo} command transition
      */
-    protected void backTo(BackTo command) {
+    protected void backTo(@NotNull BackTo command) {
         if (command.getScreen() == null) {
             backToRoot();
         } else {
@@ -214,10 +244,10 @@ public class SupportAppNavigator implements Navigator {
      * @param nextFragment        next screen fragment
      * @param fragmentTransaction fragment transaction
      */
-    protected void setupFragmentTransaction(Command command,
-                                            Fragment currentFragment,
-                                            Fragment nextFragment,
-                                            FragmentTransaction fragmentTransaction) {
+    protected void setupFragmentTransaction(@NotNull Command command,
+                                            @Nullable Fragment currentFragment,
+                                            @Nullable Fragment nextFragment,
+                                            @NotNull FragmentTransaction fragmentTransaction) {
     }
 
     /**
@@ -227,11 +257,12 @@ public class SupportAppNavigator implements Navigator {
      * @param activityIntent activity intent
      * @return transition options
      */
-    protected Bundle createStartActivityOptions(Command command, Intent activityIntent) {
+    @Nullable
+    protected Bundle createStartActivityOptions(@NotNull Command command, @NotNull Intent activityIntent) {
         return null;
     }
 
-    private void checkAndStartActivity(SupportAppScreen screen, Intent activityIntent, Bundle options) {
+    private void checkAndStartActivity(@NotNull SupportAppScreen screen, @NotNull Intent activityIntent, @Nullable Bundle options) {
         // Check if we can start activity
         if (activityIntent.resolveActivity(activity.getPackageManager()) != null) {
             activity.startActivity(activityIntent, options);
@@ -246,7 +277,7 @@ public class SupportAppNavigator implements Navigator {
      * @param screen         screen
      * @param activityIntent intent passed to start Activity for the {@code screenKey}
      */
-    protected void unexistingActivity(SupportAppScreen screen, Intent activityIntent) {
+    protected void unexistingActivity(@NotNull SupportAppScreen screen, @NotNull Intent activityIntent) {
         // Do nothing by default
     }
 
@@ -256,11 +287,13 @@ public class SupportAppNavigator implements Navigator {
      * @param screen screen
      * @return instantiated fragment for the passed screen
      */
-    protected Fragment createFragment(SupportAppScreen screen) {
+    @Nullable
+    protected Fragment createFragment(@NotNull SupportAppScreen screen) {
         Fragment fragment = screen.getFragment();
 
         if (fragment == null) {
             errorWhileCreatingScreen(screen);
+            throw new RuntimeException("Can't create a screen: " + screen.getScreenKey());
         }
         return fragment;
     }
@@ -271,11 +304,29 @@ public class SupportAppNavigator implements Navigator {
      *
      * @param screen screen
      */
-    protected void backToUnexisting(SupportAppScreen screen) {
+    protected void backToUnexisting(@NotNull SupportAppScreen screen) {
         backToRoot();
     }
 
-    protected void errorWhileCreatingScreen(SupportAppScreen screen) {
-        throw new RuntimeException("Can't create a screen: " + screen.getScreenKey());
+    /**
+     * Called when we tried to create new intent or fragment but didn't receive them.
+     *
+     * @param screen screen
+     */
+    protected void errorWhileCreatingScreen(@NotNull SupportAppScreen screen) {
+        // Do nothing by default
+    }
+
+    /**
+     * Override this method if you want to handle apply command error.
+     *
+     * @param command command
+     * @param error   error
+     */
+    protected void errorOnApplyCommand(
+            @NotNull Command command,
+            @NotNull RuntimeException error
+    ) {
+        throw error;
     }
 }

library/src/main/java/ru/terrakok/cicerone/android/support/SupportAppScreen.java

@@ -2,8 +2,11 @@ package ru.terrakok.cicerone.android.support;
 
 import android.content.Context;
 import android.content.Intent;
-import android.support.v4.app.Fragment;
 
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import androidx.fragment.app.Fragment;
 import ru.terrakok.cicerone.Screen;
 
 /**
@@ -13,11 +16,18 @@ import ru.terrakok.cicerone.Screen;
  */
 public abstract class SupportAppScreen extends Screen {
 
+    @Nullable
     public Fragment getFragment() {
         return null;
     }
 
-    public Intent getActivityIntent(Context context) {
+    @Nullable
+    public Intent getActivityIntent(@NotNull Context context) {
+        return null;
+    }
+
+    @Nullable
+    public FragmentParams getFragmentParams() {
         return null;
     }
 }

library/src/main/java/ru/terrakok/cicerone/commands/BackTo.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone.commands;
 
+import org.jetbrains.annotations.Nullable;
+
 import ru.terrakok.cicerone.Navigator;
 import ru.terrakok.cicerone.Screen;
 
@@ -20,10 +22,11 @@ public class BackTo implements Command {
      *
      * @param screen screen
      */
-    public BackTo(Screen screen) {
+    public BackTo(@Nullable Screen screen) {
         this.screen = screen;
     }
 
+    @Nullable
     public Screen getScreen() {
         return screen;
     }

library/src/main/java/ru/terrakok/cicerone/commands/Forward.java

@@ -4,6 +4,8 @@
 
 package ru.terrakok.cicerone.commands;
 
+import org.jetbrains.annotations.NotNull;
+
 import ru.terrakok.cicerone.Screen;
 
 /**
@@ -17,10 +19,11 @@ public class Forward implements Command {
      *
      * @param screen screen
      */
-    public Forward(Screen screen) {
+    public Forward(@NotNull Screen screen) {
         this.screen = screen;
     }
 
+    @NotNull
     public Screen getScreen() {
         return screen;
     }

library/src/main/java/ru/terrakok/cicerone/commands/Replace.java

@@ -4,12 +4,15 @@
 
 package ru.terrakok.cicerone.commands;
 
+import org.jetbrains.annotations.NotNull;
+
 import ru.terrakok.cicerone.Screen;
 
 /**
  * Replaces the current screen.
  */
 public class Replace implements Command {
+    @NotNull
     private Screen screen;
 
     /**
@@ -17,10 +20,11 @@ public class Replace implements Command {
      *
      * @param screen screen
      */
-    public Replace(Screen screen) {
+    public Replace(@NotNull Screen screen) {
         this.screen = screen;
     }
 
+    @NotNull
     public Screen getScreen() {
         return screen;
     }

library/stub-android/src/main/java/androidx/fragment/app/Fragment.java

@@ -1,6 +1,7 @@
-package android.support.v4.app;
+package androidx.fragment.app;
 
 import android.os.Bundle;
+import androidx.fragment.app.FragmentActivity;
 
 /**
  * Created by Konstantin Tckhovrebov (aka @terrakok)

library/stub-android/src/main/java/androidx/fragment/app/FragmentActivity.java

@@ -1,4 +1,4 @@
-package android.support.v4.app;
+package androidx.fragment.app;
 
 import android.app.Activity;
 

library/stub-android/src/main/java/androidx/fragment/app/FragmentManager.java

@@ -1,4 +1,4 @@
-package android.support.v4.app;
+package androidx.fragment.app;
 
 /**
  * Created by Konstantin Tckhovrebov (aka @terrakok)

library/stub-android/src/main/java/androidx/fragment/app/FragmentTransaction.java

@@ -1,4 +1,6 @@
-package android.support.v4.app;
+package androidx.fragment.app;
+
+import android.os.Bundle;
 
 /**
  * Created by Konstantin Tckhovrebov (aka @terrakok)
@@ -10,6 +12,13 @@ public class FragmentTransaction {
         throw new RuntimeException("Stub!");
     }
 
+    public final FragmentTransaction replace(
+            int containerViewId,
+            Class<? extends Fragment> fragmentClass,
+            Bundle args) {
+        throw new RuntimeException("Stub!");
+    }
+
     public FragmentTransaction addToBackStack(String name) {
         throw new RuntimeException("Stub!");
     }

sample/build.gradle

@@ -5,11 +5,11 @@ repositories {
 }
 
 android {
-    compileSdkVersion 25
+    compileSdkVersion 28
 
     defaultConfig {
         minSdkVersion 21
-        targetSdkVersion 25
+        targetSdkVersion 28
         versionCode 1
         versionName "1.0.0"
         applicationId "ru.terrakok.cicerone.sample"
@@ -27,15 +27,15 @@ android {
 }
 
 ext {
-    supportLibraryVersion = "25.3.0"
+    androidXVersion = "1.0.0"
     moxyVersion = "1.4.6"
     daggerVersion = "2.10"
 }
 
 dependencies {
     // Support libraries
-    implementation "com.android.support:appcompat-v7:$supportLibraryVersion"
-    implementation "com.android.support:design:$supportLibraryVersion"
+    implementation "androidx.appcompat:appcompat:$androidXVersion"
+    implementation "com.google.android.material:material:$androidXVersion"
 
     //MVP Moxy
     implementation "com.arello-mobile:moxy:$moxyVersion"

sample/src/main/java/ru/terrakok/cicerone/sample/Screens.java

@@ -3,7 +3,7 @@ package ru.terrakok.cicerone.sample;
 import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
-import android.support.v4.app.Fragment;
+import androidx.fragment.app.Fragment;
 
 import ru.terrakok.cicerone.android.support.SupportAppScreen;
 import ru.terrakok.cicerone.sample.ui.animations.ProfileActivity;

sample/src/main/java/ru/terrakok/cicerone/sample/ui/animations/ProfileActivity.java

@@ -1,10 +1,10 @@
 package ru.terrakok.cicerone.sample.ui.animations;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
-import android.support.v7.app.AppCompatActivity;
+import androidx.annotation.Nullable;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentTransaction;
 import android.transition.ChangeBounds;
 import android.view.View;
 

sample/src/main/java/ru/terrakok/cicerone/sample/ui/animations/photos/SelectPhotoFragment.java

@@ -1,12 +1,12 @@
 package ru.terrakok.cicerone.sample.ui.animations.photos;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;
 
+import androidx.annotation.Nullable;
 import com.arellomobile.mvp.MvpAppCompatFragment;
 import com.arellomobile.mvp.presenter.InjectPresenter;
 import com.arellomobile.mvp.presenter.ProvidePresenter;
@@ -26,7 +26,8 @@ import ru.terrakok.cicerone.sample.ui.common.BackButtonListener;
  * Created by Konstantin Tskhovrebov (aka @terrakok) on 14.07.17.
  */
 
-public class SelectPhotoFragment extends MvpAppCompatFragment implements SelectPhotoView, BackButtonListener {
+public class SelectPhotoFragment extends MvpAppCompatFragment
+    implements SelectPhotoView, BackButtonListener {
     private static final String ARG_ANIM_DESTINATION = "arg_anim_dest";
 
     private ImageView photo1;

sample/src/main/java/ru/terrakok/cicerone/sample/ui/animations/profile/ProfileFragment.java

@@ -1,12 +1,12 @@
 package ru.terrakok.cicerone.sample.ui.animations.profile;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ImageView;
 
+import androidx.annotation.Nullable;
 import com.arellomobile.mvp.MvpAppCompatFragment;
 import com.arellomobile.mvp.presenter.InjectPresenter;
 import com.arellomobile.mvp.presenter.ProvidePresenter;

sample/src/main/java/ru/terrakok/cicerone/sample/ui/bottom/BottomNavigationActivity.java

@@ -1,9 +1,9 @@
 package ru.terrakok.cicerone.sample.ui.bottom;
 
 import android.os.Bundle;
-import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentManager;
-import android.support.v4.app.FragmentTransaction;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentManager;
+import androidx.fragment.app.FragmentTransaction;
 
 import com.arellomobile.mvp.MvpAppCompatActivity;
 import com.arellomobile.mvp.presenter.InjectPresenter;
@@ -27,7 +27,8 @@ import ru.terrakok.cicerone.sample.ui.common.RouterProvider;
 /**
  * Created by terrakok 25.11.16
  */
-public class BottomNavigationActivity extends MvpAppCompatActivity implements BottomNavigationView, RouterProvider {
+public class BottomNavigationActivity extends MvpAppCompatActivity
+    implements BottomNavigationView, RouterProvider {
     private BottomNavigationBar bottomNavigationBar;
 
     @Inject

sample/src/main/java/ru/terrakok/cicerone/sample/ui/bottom/ForwardFragment.java

@@ -1,13 +1,13 @@
 package ru.terrakok.cicerone.sample.ui.bottom;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
-import android.support.v7.widget.Toolbar;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
+import androidx.annotation.Nullable;
+import androidx.appcompat.widget.Toolbar;
 import com.arellomobile.mvp.MvpAppCompatFragment;
 import com.arellomobile.mvp.presenter.InjectPresenter;
 import com.arellomobile.mvp.presenter.ProvidePresenter;

sample/src/main/java/ru/terrakok/cicerone/sample/ui/bottom/TabContainerFragment.java

@@ -1,8 +1,8 @@
 package ru.terrakok.cicerone.sample.ui.bottom;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
-import android.support.v4.app.Fragment;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;

sample/src/main/java/ru/terrakok/cicerone/sample/ui/main/BaseFragment.java

@@ -0,0 +1,39 @@
+package ru.terrakok.cicerone.sample.ui.main;
+
+import android.content.Context;
+import androidx.fragment.app.Fragment;
+import androidx.fragment.app.FragmentActivity;
+import com.arellomobile.mvp.MvpAppCompatFragment;
+
+import java.lang.ref.WeakReference;
+import java.util.Iterator;
+import java.util.List;
+
+public abstract class BaseFragment extends MvpAppCompatFragment {
+
+    @Override
+    public void onAttach(Context context) {
+        super.onAttach(context);
+        FragmentActivity activity = getActivity();
+        if (activity instanceof ChainHolder) {
+            ((ChainHolder) activity).getChain().add(new WeakReference<Fragment>(this));
+        }
+    }
+
+    @Override
+    public void onDetach() {
+        FragmentActivity activity = getActivity();
+        if (activity instanceof ChainHolder) {
+            List<WeakReference<Fragment>> chain = ((ChainHolder) activity).getChain();
+            for (Iterator<WeakReference<Fragment>> it = chain.iterator(); it.hasNext();) {
+                WeakReference<Fragment> fragmentReference = it.next();
+                Fragment fragment = fragmentReference.get();
+                if (fragment != null && fragment == this) {
+                    it.remove();
+                    break;
+                }
+            }
+        }
+        super.onDetach();
+    }
+}

sample/src/main/java/ru/terrakok/cicerone/sample/ui/main/ChainHolder.java

@@ -0,0 +1,10 @@
+package ru.terrakok.cicerone.sample.ui.main;
+
+import androidx.fragment.app.Fragment;
+
+import java.lang.ref.WeakReference;
+import java.util.List;
+
+public interface ChainHolder {
+    List<WeakReference<Fragment>> getChain();
+}

sample/src/main/java/ru/terrakok/cicerone/sample/ui/main/MainActivity.java

@@ -1,16 +1,17 @@
 package ru.terrakok.cicerone.sample.ui.main;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
-import android.support.v4.app.Fragment;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
 import android.widget.TextView;
 
 import com.arellomobile.mvp.MvpAppCompatActivity;
-
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 
+import java.util.List;
 import javax.inject.Inject;
 
 import ru.terrakok.cicerone.Navigator;
@@ -28,8 +29,9 @@ import ru.terrakok.cicerone.sample.ui.common.BackButtonListener;
  * on 11.10.16
  */
 
-public class MainActivity extends MvpAppCompatActivity {
+public class MainActivity extends MvpAppCompatActivity implements ChainHolder {
     private TextView screensSchemeTV;
+    private List<WeakReference<Fragment>> chain = new ArrayList<>();
 
     @Inject
     NavigatorHolder navigatorHolder;
@@ -84,10 +86,11 @@ public class MainActivity extends MvpAppCompatActivity {
 
     private void printScreensScheme() {
         ArrayList<SampleFragment> fragments = new ArrayList<>();
-        for (Fragment fragment : getSupportFragmentManager().getFragments()) {
-            if (fragment instanceof SampleFragment) {
-                fragments.add((SampleFragment) fragment);
-            }
+        for (WeakReference<Fragment> fragmentReference : chain) {
+          Fragment fragment = fragmentReference.get();
+          if (fragment != null && fragment instanceof SampleFragment) {
+            fragments.add((SampleFragment) fragment);
+          }
         }
         Collections.sort(fragments, new Comparator<SampleFragment>() {
             @Override
@@ -105,4 +108,9 @@ public class MainActivity extends MvpAppCompatActivity {
         }
         screensSchemeTV.setText("Chain: " + keys.toString() + "");
     }
+
+    @Override
+    public List<WeakReference<Fragment>> getChain() {
+        return chain;
+    }
 }

sample/src/main/java/ru/terrakok/cicerone/sample/ui/main/SampleFragment.java

@@ -1,13 +1,11 @@
 package ru.terrakok.cicerone.sample.ui.main;
 
 import android.os.Bundle;
-import android.support.annotation.Nullable;
-import android.support.v7.widget.Toolbar;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-
-import com.arellomobile.mvp.MvpAppCompatFragment;
+import androidx.annotation.Nullable;
+import androidx.appcompat.widget.Toolbar;
 import com.arellomobile.mvp.presenter.InjectPresenter;
 import com.arellomobile.mvp.presenter.ProvidePresenter;
 
@@ -25,7 +23,7 @@ import ru.terrakok.cicerone.sample.ui.common.BackButtonListener;
  * on 11.10.16
  */
 
-public class SampleFragment extends MvpAppCompatFragment implements SampleView, BackButtonListener {
+public class SampleFragment extends BaseFragment implements SampleView, BackButtonListener {
     private static final String EXTRA_NUMBER = "extra_number";
     private static final String EXTRA_TIME = "extra_time";
 

sample/src/main/res/layout/activity_start.xml

@@ -5,7 +5,7 @@
     android:layout_height="match_parent"
     android:orientation="vertical">
 
-    <android.support.v4.widget.Space
+    <androidx.legacy.widget.Space
         android:layout_width="wrap_content"
         android:layout_height="0dp"
         android:layout_weight="1"/>
@@ -18,7 +18,7 @@
         android:text="@string/cicerone_description"
         android:textSize="18sp"/>
 
-    <android.support.v4.widget.Space
+    <androidx.legacy.widget.Space
         android:layout_width="wrap_content"
         android:layout_height="0dp"
         android:layout_weight="1"/>

sample/src/main/res/layout/fragment_forward.xml

@@ -7,7 +7,7 @@
     android:layout_height="match_parent"
     android:orientation="vertical">
 
-    <android.support.v7.widget.Toolbar
+    <androidx.appcompat.widget.Toolbar
         android:id="@+id/toolbar"
         android:layout_width="match_parent"
         android:layout_height="?attr/actionBarSize"
@@ -15,7 +15,7 @@
         app:navigationIcon="@drawable/ic_arrow_back_white_24dp"
         app:title="@string/app_name"/>
 
-    <android.support.v4.widget.Space
+    <androidx.legacy.widget.Space
         android:layout_width="wrap_content"
         android:layout_height="0dp"
         android:layout_weight="1"/>
@@ -48,7 +48,7 @@
         android:text="github"
         android:textSize="20sp"/>
 
-    <android.support.v4.widget.Space
+    <androidx.legacy.widget.Space
         android:layout_width="wrap_content"
         android:layout_height="0dp"
         android:layout_weight="1"/>

sample/src/main/res/layout/fragment_sample.xml

@@ -5,7 +5,7 @@
               android:layout_height="match_parent"
               android:orientation="vertical">
 
-    <android.support.v7.widget.Toolbar
+    <androidx.appcompat.widget.Toolbar
         android:id="@+id/toolbar"
         android:layout_width="match_parent"
         android:layout_height="?attr/actionBarSize"