Proper use of sub sub fragments with (Child)FragmentManager

Question

How do I properly use Fragments in Fragments?

My (simplified) use case is following, I have an activity with a layout fragment and this fragment theirself contains a sub

Answer 1

You should add SubFragment to Fragment the same way like you add Fragment to Activity. I mean adding Fragment to Activity should look like:

 @Override
 public void onCreate(Bundle savedInstanceState) {
   ....
   if (savedInstanceState == null){
      //add fragment
      mMainFragment = new MainFragment();
      FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
      transaction.replace(R.id.fragment_main, mMainFragment);
      transaction.commit();
   }
 }

Adding SubFragment to MainFragment should look like:

    public class MainFragment extends Fragment{

      @Override
      public View onCreateView(LayoutInflater i, ViewGroup c, Bundle savedInstanceState) {
           ...
        if (savedInstanceState == null){
           mSubFragment = new SubFragment();

           //add child fragment
           getChildFragmentManager()
                   .beginTransaction()
                   .add(R.id.fragment_sub, mSubFragment, "tag")
                   .commit();
        }
      }
    }

or you can add child fragment to Fragment in onCreate method