How to get a list of backstack fragment entries in android?

Question

I'm working on an application in which tabs are implemented using FragmentActivity. Since, tabs are required throughout the application, fragments are used extensively to make the application compatible on all the versions of android.

As a consequence, I'm facing a problem in visualizing as to what fragments are present on the backstack. I'm sure there is a way to retrieve the list of fragments present on the backstack. Thanks.

Schoof

Answer 1

The FragmentManager has methods:

getBackStackEntryCount()

getBackStackEntryAt (int index)

FragmentManager fm = getFragmentManager();

for(int entry = 0; entry<fm.getBackStackEntryCount(); entry++){
   Log.i(TAG, "Found fragment: " + fm.getBackStackEntryAt(entry).getId());
}

Extrados

getId returns the id of backstack not the fragment – Susy

Downvote because this is wrong. If you execute findFragmentById() and use these ids, you will not find a fragment. – Leitmotiv

Answer 2

I have achieved logging of fragments in the back stack with this code (in Kotlin):

findNavController().backQueue.forEach {
        Log.d(TAG, "${it.destination}")
    }

This code iterates through every entry in the navigation back stack, printing out the destination name of the Fragment.

Ransome

Hi backQueue doesn't exist ? – Kremenchug

backQueue is private and you can not access it. – Parada

Answer 3

If you want to check which fragment is visible and if you know the id of view where fragment is placed, first you have to add below in onCreate()

    getSupportFragmentManager().addOnBackStackChangedListener(new OnBackStackChangedListener() {

  @Override
  public void onBackStackChanged() {
    Fragment f = getSupportFragmentManager().findFragmentById(R.id.content_frame);
    if (f != null){
      updateActionBarTitle(f);
    }

  }
});

private void updateActionBarTitle(Fragment fragment) {
        String fragClassName = fragment.getClass().getName();

        if (fragClassName.equals(FirstFragment.class.getName())) {
            setTitle("Home");
        } else if (fragClassName.equals(SecondFragment.class.getName())) {
            setTitle("Second");
        }
    }

This will update your action bar title on back stack change listener.

Gendron

How is this an answer to the question asked? – Hypochondriac

This doesn't seem to be related to the question asked. – Eelpout