FragmentManager know when a fragment resumed

Question

I have a FragmentManager that I am using to add Fragments onto the backStack .

FragmentTransaction ft = getFragmentManager().beginTransaction();
PUCCoursesSubjectList detail = new PUCCoursesSubjectList();
detail.item = item;

ft.add(R.id.container_frame, detail, "courses_detail");
ft.addToBackStack(null);
ft.commit();

Once I have a few Fragments on the stack, I pop one off, but I need to know when the previous fragment is shown again.

It seems that onResume doesn't apply here. Is there another method that I should be using to know when a Fragment , that is already in the FragmentManger , appears?

Answer 1

When you pop your fragment, you could get your other fragment from the fragment manager by the tag you provided and call a public method in your fragment.

YourFragment fragment = (YourFragment) getFragmentManager().findFragmentByTag("FRAGMENT_TAG");

if (fragment != null) {
   fragment.callMethod();
}

Answer 2

The accepted answer could not work: getFragmentManager may return null in some case (ie Activity has been destroyed)

Now it's better to use Lifecycle, like in the next example:

  if( getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.RESUMED) )
  {
      // Do whatever you need
  }

Answer 3

You can check by the tag if it is visible and not null by suing the tag

MyFragment myFragment = (MyFragment)getFragmentManager().findFragmentByTag("MY_FRAGMENT");
if (myFragment != null && myFragment.isVisible()) {
   // add your code here
}