Is there a way to get fragment from top of stack?

Some thing like this should help your activity figure this out on backpress:

private Fragment getCurrentFragment(){
    FragmentManager fragmentManager = getSupportFragmentManager();
    String fragmentTag = fragmentManager.getBackStackEntryAt(fragmentManager.getBackStackEntryCount() - 1).getName();
    Fragment currentFragment = fragmentManager.findFragmentByTag(fragmentTag);
    return currentFragment;
}

@Override
public void onBackPressed() {
    Fragment fragmentBeforeBackPress = getCurrentFragment();
    // Perform the usual back action
    super.onBackPressed();
    Fragment fragmentAfterBackPress = getCurrentFragment();
}

Hope this helps.