Hide TabLayout and Toolbar in some Fragments / Handling onPause/onResume correctly

Question

I am using a single Activity approach with a Navigation Graph. I don't want my tab layout or the toolbar visible in some fragments. I wrote a superclass to extend from in those fragments i don't want the bars. But somehow i do not understand the lifecycle correctly as this is not working:

 public class NoTabLayoutFragment extends Fragment {

    @Override
    public void onResume() {
        super.onResume();
        hideTabLayout();

    }

    @Override
    public void onPause() {
        super.onPause();
        showTabLayout();
    }

    private void showTabLayout() {
        if (getActivity() != null && getActivity().findViewById(R.id.fragment_main_tab_layout) != null) {
            getActivity().findViewById(R.id.fragment_main_tab_layout).setVisibility(View.VISIBLE);
        }

    }

    private void hideTabLayout() {
        if (getActivity() != null && getActivity().findViewById(R.id.fragment_main_tab_layout) != null) {
            getActivity().findViewById(R.id.fragment_main_tab_layout).setVisibility(View.GONE);
        }

    }
}  

and

public class NoBarsFragment extends NoTabLayoutFragment {
    @Override
    public void onResume() {
        super.onResume();
        hideToolbar();
    }

    @Override
    public void onPause() {
        super.onPause();
        showToolbar();
    }

    private void hideToolbar() {
        if (getActivity() != null && ((AppCompatActivity) getActivity()).getSupportActionBar() != null) {
            ((AppCompatActivity) getActivity()).getSupportActionBar().hide();
        }
    }

    private void showToolbar() {
        if (getActivity() != null && ((AppCompatActivity) getActivity()).getSupportActionBar() != null) {
            ((AppCompatActivity) getActivity()).getSupportActionBar().show();
        }
    }
}

What am i doing wrong?

Answer 1

As per the Listen for Navigation Events documentation, the correct way to change UI visibility is via an OnDestinationChangedListener:

navController.addOnDestinationChangedListener(new NavController.OnDestinationChangedListener() {
    @Override
    public void onDestinationChanged(@NonNull NavController controller,
           @NonNull NavDestination destination, @Nullable Bundle arguments) {
       if(destination.getId() == R.id.full_screen_destination) {
           getSupportActionBar().hide()
       } else {
           getSupportActionBar().show()
       }
   }
});