public void registerOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener listener){
  if (listener != null) {
    registerListener(listener);
  }
}

public void registerOnSharedPreferenceChangeListener ( OnSharedPreferenceChangeListener listener ) { if ( listener != null ) { registerListener ( listener ) ; } }
registers a callback to be invoked when a change happens to a preference .
