/* Serializing cities */
 @Override
 public void onStop() {
   cityAdapter.revertData();
   preferencesManager.saveListToFile(cityAdapter.getCities());
   super.onStop();
 }
 private void readcities() {
   List<City> cities = preferencesManager.readListFromFile();
   cityAdapter = new CityAdapter(activity, cities);
   setListAdapter(cityAdapter);
 }