Call methods on a fragment when clearing the back stack

Question

I'm developing an Android application with fragments. These fragments are lists of items. When the user selects an item, a new fragment is added to the stack.

getActivity().getSupportFragmentManager().beginTransaction()
    .add(R.id.frameContent, ListFragment.newInstance(TypeEnum.comunidades,
                                  resultsvalue.get(position).getIdentificador(),
                                  resultsvalue.get(position).getIdentificador(),
                                  resultsvalue.get(position).getNombre()))
                                  .addToBackStack(null).commit();

The user has the option to go back (to previous list), but when I go back to the previous fragment no lifecycle method is called. When I'm adding a new fragment, the fragment below does not execute onPause() nor onStop() , so when go back to the fragment below the top of the stack I have no callback to run methods.

Answer 1

As I understood your question, you are saying that when going back to the main fragment, it is somewhat not initialized because it wasn't destroyed before.

In this case I believe you want to use replace() rather than add() . That way the replaced fragment will go through the destroy process, calling both onPause / onStop.

Calling methods on your still-alive fragment can be done as follows:

FragmentManager fm = getSupportFragmentManager();
MainFragment f = (MainFragment) fm.findFragmentByTag("YOUR_TAG");
f.doSomething();

You can specify your tag when you first add the main fragment to the container.

Answer 2

使用replace()代替add() 。

getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.frameContent, ListFragment.newInstance(TypeEnum.comunidades, resultsvalue.get(position).getIdentificador(), resultsvalue.get(position).getIdentificador(), resultsvalue.get(position).getNombre())).addToBackStack(null).commit();