FragmentContainerView using findNavController

Question

I\'m using Android Navigation Component with bottom navigation, lint gives a warning about replacing the tag with FragmentContainerView

Answer 1

Replace this line:

NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);

with

NavController navController = getNavController();

Where getNavController() looks like this:

    // workaround for https://issuetracker.google.com/issues/142847973
    @NonNull
    private NavController getNavController() {
        Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment);
        if (!(fragment instanceof NavHostFragment)) {
            throw new IllegalStateException("Activity " + this
                    + " does not have a NavHostFragment");
        }
        return ((NavHostFragment) fragment).getNavController();
    }

Answer 2

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).

Answer 3

On top of the accepted answer, a little shortcut what could be used is:

supportFragmentManager.findFragmentById(R.id.navHostMain)?.findNavController()

Regards