RecyclerELE Code Samples

MainActivity.java

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks < List < GuardianStory >> {
  /*Adapter for the stories*/
  private GuardianStoryAdapter guardianStoryAdapter;
  /*Create the Recycler View*/
  private RecyclerView storyListView;
  /*Reference to the progress Bar*/
  private ProgressBar progressBar;
  /*Get a reference to the LoaderManager to intereact with the Loaders*/
  private LoaderManager loaderManager;
  /*Reference to the error(hint) TextView*/
  private TextView hintView;
  /*Reference the stories.*/
  List < GuardianStory > stories;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   loaderManager = getLoaderManager();
   //Initialize Progress bar
   progressBar = (ProgressBar) findViewById(R.id.progressBar);
   //Initialize TextView
   hintView = (TextView) findViewById(R.id.errorHint);
   //Create RecyclerView
   storyListView = (RecyclerView) findViewById(R.id.stories_list);
   storyListView.setVisibility(View.GONE);
   //Create GuardianStory list;
   stories = new ArrayList < > ();
   //get GuardianStoryAdapter
   guardianStoryAdapter = new GuardianStoryAdapter(this, stories);
   storyListView.setAdapter(guardianStoryAdapter);
   storyListView.setLayoutManager(new LinearLayoutManager(this));
   startLoad();
  }
  /**
   * This method starts the loader to get news Stories,
   * if there is no connection, it shows the hintView stating the error
   */
  private void startLoad() {
   //Create the connectivity Manager and NetworkInfo objects to check for Network connectivity
   ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
   NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
   if (networkInfo != null && networkInfo.isConnected()) {
    //Initialize the loader. Pass the itn ID constant defined above and pass in null
    loaderManager.initLoader(STORY_LOADER_ID, null, this);
   } else {
    hintView.setText(R.string.no_internet);
    progressBar.setVisibility(View.GONE);
    hintView.setVisibility(View.VISIBLE);
    storyListView.setVisibility(View.GONE);
   }
  }
  /**
   * On Create Loader handles the setting of the View to loading and then goes on to initiate the network call i the background.
   */
  @Override
  public Loader < List < GuardianStory >> onCreateLoader(int id, Bundle args) {
   progressBar.setVisibility(View.VISIBLE);
   hintView.setVisibility(View.GONE);
   .
   .
   .
   return new StoryLoader(this, URI());
  }
  /**
   * OnLoadFinish Method handles the loading of stories in the list,
   * If the list is empty, it shows the error view
   */
  @Override
  public void onLoadFinished(Loader < List < GuardianStory >> loader, List < GuardianStory > guardianStoryList) {
   guardianStoryAdapter.clearData();
   if (guardianStoryList != null && !guardianStoryList.isEmpty()) {
    stories.addAll(guardianStoryList);
    guardianStoryAdapter.notifyDataSetChanged();
    storyListView.setVisibility(View.VISIBLE);
    progressBar.setVisibility(View.GONE);
    hintView.setVisibility(View.GONE);
   } else {
    storyListView.setVisibility(View.GONE);
    progressBar.setVisibility(View.GONE);
    hintView.setVisibility(View.VISIBLE);
    hintView.setText(R.string.error_getting_data);
   }
  }