public class SampleListActivity extends ListActivity implementsLoaderManager.LoaderCallbacks<Cursor> {private static final String[] PROJECTION = new String[] { "_id", "text_column" };// The loader's unique id. Loader ids are specific to the Activity or// Fragment in which they reside.private static final int LOADER_ID = 1;// The callbacks through which we will interact with the LoaderManager.private LoaderManager.LoaderCallbacks<Cursor> mCallbacks;// The adapter that binds our data to the ListViewprivate SimpleCursorAdapter mAdapter;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);String[] dataColumns = { "text_column" };int[] viewIDs = { R.id.text_view };// Initialize the adapter. Note that we pass a 'null' Cursor as the// third argument. We will pass the adapter a Cursor only when the// data has finished loading for the first time (i.e. when the// LoaderManager delivers the data to onLoadFinished). Also note// that we have passed the '0' flag as the last argument. This// prevents the adapter from registering a ContentObserver for the// Cursor (the CursorLoader will do this for us!).mAdapter = new SimpleCursorAdapter(this, R.layout.list_item,null, dataColumns, viewIDs, 0);// Associate the (now empty) adapter with the ListView.setListAdapter(mAdapter);// The Activity (which implements the LoaderCallbacks<Cursor>// interface) is the callbacks object through which we will interact// with the LoaderManager. The LoaderManager uses this object to// instantiate the Loader and to notify the client when data is made// available/unavailable.mCallbacks = this;// Initialize the Loader with id '1' and callbacks 'mCallbacks'.// If the loader doesn't already exist, one is created. Otherwise,// the already created Loader is reused. In either case, the// LoaderManager will manage the Loader across the Activity/Fragment// lifecycle, will receive any new loads once they have completed,// and will report this new data back to the 'mCallbacks' object.LoaderManager lm = getLoaderManager();lm.initLoader(LOADER_ID, null, mCallbacks);}@Overridepublic Loader<Cursor> onCreateLoader(int id, Bundle args) {// Create a new CursorLoader with the following query parameters.return new CursorLoader(SampleListActivity.this, CONTENT_URI,PROJECTION, null, null, null);}@Overridepublic void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {// A switch-case is useful when dealing with multiple Loaders/IDsswitch (loader.getId()) {case LOADER_ID:// The asynchronous load is complete and the data// is now available for use. Only now can we associate// the queried Cursor with the SimpleCursorAdapter.mAdapter.swapCursor(cursor);break;}// The listview now displays the queried data.}@Overridepublic void onLoaderReset(Loader<Cursor> loader) {// For whatever reason, the Loader's data is now unavailable.// Remove any references to the old data by replacing it with// a null Cursor.mAdapter.swapCursor(null);}
}