Handling ActionBar title with the fragment back stack?

Question

I have an Activity where I load in a ListFragment and, upon clicking, it drills down a level and a new type of ListFragment is shown,

Answer 1

As described here my solution is adding this code to MainActivity onCreate method(): and changing actionbar title

FragmentManager fragmentManager=getSupportFragmentManager();
fragmentManager.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
    @Override
    public void onBackStackChanged() {
        Fragment currentFragment = fragmentManager.findFragmentById(R.id.My_Container_1_ID);
        currentFragment.onResume();
    }
});

and changing actionbar title in fragment's onResume() method

@Override
public void onResume() {
    super.onResume();
    AppCompatActivity activity = (AppCompatActivity) getActivity();
    ActionBar actionBar = activity.getSupportActionBar();
    if(actionBar!=null) {
        actionBar.setTitle("Fragment Title");
        actionBar.setSubtitle("Subtitle");
    }

}