restore existing fragment

restoringFragment.java

private void changeFragment(Fragment f, String tag) {
    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    if (fragmentManager.findFragmentByTag(tag) == null) {
        fragmentTransaction.add(R.id.frameContainer, f, tag);
    } else {
        f = fragmentManager.findFragmentByTag(tag);
        fragmentTransaction.replace(R.id.frameContainer, f, tag);
    }
    fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).commit();
}