public class BackPressedImpl implements OnBackPressedListener {
    private Fragment parent;

    public BackPressedImpl(Fragment fragment) {
        this.parent = fragment;
    }

    @Override
    public boolean doBack() {
        MainActivity activity = (MainActivity) parent.getActivity();
        PagerFragment fragment = (PagerFragment) activity.getSupportFragmentManager().getFragments().get(0);
        return fragment.onBackPressed();
    }
}