How to properly handle back navigation in a multi-fragment setup using Jetpack Navigation Component?
I'm collaborating on a project where I've searched everywhere and can't find a clear answer. This might be a silly question, but I'm encountering an issue with back navigation in my Android app that uses Jetpack's Navigation Component... I have a main fragment that hosts two child fragments, and I'm trying to implement back navigation correctly. When I press the back button, I expect to navigate back to the main fragment, but instead, it exits the app. I've set up my navigation graph with the following configuration: ```xml <fragment android:id="@+id/mainFragment" android:name="com.example.app.MainFragment" tools:layout="@layout/fragment_main"> <action android:id="@+id/action_mainFragment_to_childFragment1" app:destination="@id/childFragment1" /> <action android:id="@+id/action_mainFragment_to_childFragment2" app:destination="@id/childFragment2" /> </fragment> <fragment android:id="@+id/childFragment1" android:name="com.example.app.ChildFragment1" tools:layout="@layout/fragment_child1" /> <fragment android:id="@+id/childFragment2" android:name="com.example.app.ChildFragment2" tools:layout="@layout/fragment_child2" /> ``` In my `MainFragment`, I handle the navigation to the child fragments like this: ```kotlin class MainFragment : Fragment() { private lateinit var navController: NavController override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { val view = inflater.inflate(R.layout.fragment_main, container, false) navController = Navigation.findNavController(requireActivity(), R.id.nav_host_fragment) view.findViewById<Button>(R.id.buttonToChild1).setOnClickListener { navController.navigate(R.id.action_mainFragment_to_childFragment1) } return view } } ``` I also have a custom back button handler in the child fragments: ```kotlin class ChildFragment1 : Fragment() { override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner) { // This doesn't seem to work as expected findNavController().navigateUp() } } } ``` When I navigate to `ChildFragment1` and press the back button, it just exits the app instead of returning to `MainFragment`. I've tried using `findNavController().navigateUp()` and even `popBackStack()`, but neither seems to yield the expected behavior. The `childFragment1` is not being added to the back stack correctly. I've checked my dependencies and I'm using: ```gradle implementation "androidx.navigation:navigation-fragment-ktx:2.5.0" implementation "androidx.navigation:navigation-ui-ktx:2.5.0" ``` How can I ensure proper back navigation in my fragment setup? Is there something I'm missing in the configuration? Has anyone else encountered this? I'm working in a macOS environment. Thanks for any help you can provide! This is my first time working with Kotlin 3.9. Any examples would be super helpful.