isValidFragment Android API 19

Out of pure curiosity, you can also do this as well:

@Override
protected boolean isValidFragment(String fragmentName) {
    return MyPreferenceFragmentA.class.getName().equals(fragmentName)
            || MyPreferenceFragmentB.class.getName().equals(fragmentName)
            || // ... Finish with your last fragment.

;}

Try this... this is how we check validity of fragment.

protected boolean isValidFragment(String fragmentName) {
  return StockPreferenceFragment.class.getName().equals(fragmentName);
}