IssueTracker

Can you attach a sample project that reproduces your issue?

I'm experiencing this issue in a commercial non-open source project so I'd have to provide extracted code fragments. The menu file for instance looks similar to this:

<menu>
    <item
        android:id="@+id/destination_one" />

    <item
        android:id="@+id/destination_two" />

    <item
        android:id="@+id/destination_three" />

    <item
        android:id="@+id/destination_four" />
</menu>

The menu item ids match the top level destination ids as for instance destination_one as required by the NavigationUI library.

The xml layout file of the main activity (there is only one activity) looks pretty much like this:

<androidx.coordinatorlayout.widget.CoordinatorLayout>

    <androidx.constraintlayout.widget.ConstraintLayout>

        <androidx.fragment.app.FragmentContainerView
            android:id="@+id/navigation_host_fragment"
            android:name="androidx.navigation.fragment.NavHostFragment"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            app:defaultNavHost="true"
            app:layout_constraintBottom_toTopOf="@id/bottom_navigation"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            app:navGraph="@navigation/main_navigation" />

        <com.google.android.material.bottomnavigation.BottomNavigationView
            android:id="@+id/bottom_navigation"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@id/navigation_host_fragment"
            app:menu="@menu/main_menu" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

The main_navigation is the first navigation graph I posted in the original post. The behavior I described above only affects the first bottomNavigation item which corresponds to the top level navGraph's startDestination.

Yeah, what we're looking for is a full project (i.e., take a brand new project in Android Studio, put your few bits of code in, and make sure your problem reproduces) as there are a lot of little pieces that can make a difference here.

https://github.com/postfixNotation/NavigationUI

Of course the logic of my project is more sophisticated but this reproduces the issue quite well. If you click the first BottomNavigation item N times you need N+1 system back navigation triggers to leave the app.

Thanks a lot for your help! I basically removed the first embedded graph by moving the code directly into the topmost navGraph and as you said, navigate directly to the start destination. As far as I can tell, it seems to work now.

This has been fixed internally and will be available in Navigation 2.6.0-alpha05