List<Joke> getAllJokes() {
   List<String> jokeKeys = mNotificationHelper.getJokeKeys();
   return mJokeHelper.getJokes(jokeKeys.toArray(new String[jokeKeys.size()]));
 }
 NotificationDbManager(Context context) {
   mNotificationHelper = NotificationDbHelper.getInstance(context);
   mJokeHelper = JokeDbHelper.getInstance(context);
 }