IssueTracker

Using DynamicNavHostFragment in androidx.navigation:*:2.6.0-alpha05 cause an IllegalStateException when navigating.

Stacktrace:

FATAL EXCEPTION: main Process: com.geekorum.rdv.bwemanje.debug, PID: 10981 java.lang.IllegalStateException: You cannot access the Navigator's state until the Navigator is attached at androidx.navigation.Navigator.getState(Navigator.kt:68) at androidx.navigation.fragment.FragmentNavigator.access$getState(FragmentNavigator.kt:53) at androidx.navigation.fragment.FragmentNavigator$1.onBackStackChangeCommitted(FragmentNavigator.kt:81) at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1954) at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1841) at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1778) at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:565) at android.os.Handler.handleCallback(Handler.java:942) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loopOnce(Looper.java:201) at android.os.Looper.loop(Looper.java:288) at android.app.ActivityThread.main(ActivityThread.java:7872) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)

This is caused by registering an OnBackStackChangeListener when constructing FragmentNavigator.

DynamicNavHostFragment first create a regular FragmentNavigator that registers his OnBackStackChangeListener. This navigator is then replaced by a DynamicFragmentNavigator. When the graph is created the navigators are all attached except the replaced FragmentNavigator which cause the crash as its OnBackStackChangeListener is still called.

To reproduce use the following layout in an activity and cause a navigation

        <androidx.fragment.app.FragmentContainerView
            android:id="@+id/nav_host_fragment"
            android:name="androidx.navigation.dynamicfeatures.fragment.DynamicNavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:defaultNavHost="true"
            app:navGraph="@navigation/mobile_navigation" />