FragmentContainerView using findNavController

Question

I'm using Android Navigation Component with bottom navigation, lint gives a warning about replacing the <fragment> tag with <FragmentContainerView> but when i replaced, findNavController is not working it gives me error about it does not have a NavController set on

Fragment

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

Activity

val navController = findNavController(R.id.nav_host_fragment)          val appBarConfiguration = AppBarConfiguration(         setOf(             R.id.navigation_classes, R.id.navigation_schedule, R.id.navigation_settings         )     )     setupActionBarWithNavController(navController, appBarConfiguration)     navView.setupWithNavController(navController) } 

Answer 1

As per this issue, when using FragmentContainerView, you need to find the NavController using findFragmentById() rather than using findNavController() when in onCreate():

val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as NavHostFragment val navController = navHostFragment.navController 

This is because findNavController(R.id.nav_host_fragment) relies on the Fragment's View to already be created which isn't the case when using FragmentContainerView (as it uses a FragmentTransaction under the hood to add the NavHostFragment).

If you are using Fragment 1.4.0 or higher and View Binding, you can simply this considerably by using the getFragment() method:

val navController = binding.container.getFragment<NavHostFragment>().navController