Loading data with Loader

So far, we have only described theoretical entities and the classes available on the API so now is the right time to show these concepts with a simple example.

In our example we will show you how to use LoaderManager, LoaderCallback, and a Loader to present an Activity that lists the name of users that are currently online for a chat application.

First, we are going to create an Activity that will act as a client to the LoaderManager and will have three buttons, INIT, RESTART, and DESTROY; to initialize the loader, to restart, and to destroy the loader respectively. The Activity will receive the LoaderCallbacks callback directly since it implements that interface as member functions:

public class WhoIsOnlineActivity extends FragmentActivity
  implements LoaderCallbacks<List<String>> {
  public static final int WHO_IS_ONLINE_LOADER_ID = 1;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
   ...
    final LoaderManager lm =  getSupportLoaderManager...