Sample Activity to fetch tweets from Twitter, store them in the db, then return the results on the main thread

TweetActivity.java

public class MainActivity extends ListActivity {
  private TweetAdapter adapter;
  private Subscription subscription;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    adapter = new TweetAdapter(this);
    setListAdapter(adapter);
    loadTweets();
  }

  private void loadTweets() {
    final AlertDialog dialog = SimpleProgressDialog.create(this, "Loading Tweets...");
    dialog.show();

    subscription = Loader.loadAndSyncTweets(this)
      .subscribeOn(Schedulers.io())
      .observeOn(AndroidSchedulers.mainThread())
      .subscribe(new Observer<List<Tweet>>() {
        @Override
        public void onCompleted() {
          dialog.dismiss();
        }

        @Override
        public void onError(Throwable e) {
          Log.e("MainActivity", "Uh oh! Error loading tweets: " + e.getCause().getMessage());
          dialog.dismiss();
        }

        @Override
        public void onNext(List<Tweet> tweets) {
          adapter.replaceWith(tweets);
          dialog.dismiss();
        }
      });
  }
}

This is from a sample skeleton Android app I have I use for experimenting.

That loader static method (Loader.loadAndSyncTweets) will:
A: load local tweets from the db in the background and return them to the UI on the main thread
B: fetch the tweets from the API in the background
C: store those freshly fetched tweets in the db in the background
D: return the new/fresh tweets to the UI on the main thread

This is a pretty common use case for client applications that interface with an API, and using RxJava makes it easy to hide all that stuff and create a more elegant client API to interface with.