public class SampleLoader extends AsyncTaskLoader<List<SampleItem>> {  // We hold a reference to the Loader’s data here.  private List<SampleItem> mData;  public SampleLoader(Context ctx) {    // Loaders may be used across multiple Activitys (assuming they aren‘t    // bound to the LoaderManager), so NEVER hold a reference to the context    // directly. Doing so will cause you to leak an entire Activity‘s context.    // The superclass constructor will store a reference to the Application    // Context instead, and can be retrieved with a call to getContext().    super(ctx);  }  /****************************************************/  /** (1) A task that performs the asynchronous load **/  /****************************************************/  @Override  public List<SampleItem> loadInBackground() {    // This method is called on a background thread and should generate a    // new set of data to be delivered back to the client.    List<SampleItem> data = http://www.mamicode.com/new ArrayList<SampleItem>();    // TODO: Perform the query here and add the results to ‘data‘.    return data;  }  /********************************************************/  /** (2) Deliver the results to the registered listener **/  /********************************************************/  @Override  public void deliverResult(List<SampleItem> data) {    if (isReset()) {      // The Loader has been reset; ignore the result and invalidate the data.      releaseResources(data);      return;    }    // Hold a reference to the old data so it doesn‘t get garbage collected.    // We must protect it until the new data has been delivered.    List<SampleItem> oldData =http://www.mamicode.com/ mData;    mData = data;    if (isStarted()) {      // If the Loader is in a started state, deliver the results to the      // client. The superclass method does this for us.      super.deliverResult(data);    }    // Invalidate the old data as we don‘t need it any more.    if (oldData != null && oldData != data) {      releaseResources(oldData);    }  }  /*********************************************************/  /** (3) Implement the Loader’s state-dependent behavior **/  /*********************************************************/  @Override  protected void onStartLoading() {    if (mData != null) {      // Deliver any previously loaded data immediately.      deliverResult(mData);    }    // Begin monitoring the underlying data source.    if (mObserver == null) {      mObserver = new SampleObserver();      // TODO: register the observer    }    if (takeContentChanged() || mData =http://www.mamicode.com/= null) {      // When the observer detects a change, it should call onContentChanged()      // on the Loader, which will cause the next call to takeContentChanged()      // to return true. If this is ever the case (or if the current data is      // null), we force a new load.      forceLoad();    }  }  @Override  protected void onStopLoading() {    // The Loader is in a stopped state, so we should attempt to cancel the     // current load (if there is one).    cancelLoad();    // Note that we leave the observer as is. Loaders in a stopped state    // should still monitor the data source for changes so that the Loader    // will know to force a new load if it is ever started again.  }  @Override  protected void onReset() {    // Ensure the loader has been stopped.    onStopLoading();    // At this point we can release the resources associated with ‘mData‘.    if (mData != null) {      releaseResources(mData);      mData = null;    }    // The Loader is being reset, so we should stop monitoring for changes.    if (mObserver != null) {      // TODO: unregister the observer      mObserver = null;    }  }  @Override  public void onCanceled(List<SampleItem> data) {    // Attempt to cancel the current asynchronous load.    super.onCanceled(data);    // The load has been canceled, so we should release the resources    // associated with ‘data‘.    releaseResources(data);  }  private void releaseResources(List<SampleItem> data) {    // For a simple List, there is nothing to do. For something like a Cursor, we     // would close it in this method. All resources associated with the Loader    // should be released here.  }  /*********************************************************************/  /** (4) Observer which receives notifications when the data changes **/  /*********************************************************************/   // NOTE: Implementing an observer is outside the scope of this post (this example  // uses a made-up "SampleObserver" to illustrate when/where the observer should   // be initialized).     // The observer could be anything so long as it is able to detect content changes  // and report them to the loader with a call to onContentChanged(). For example,  // if you were writing a Loader which loads a list of all installed applications  // on the device, the observer could be a BroadcastReceiver that listens for the  // ACTION_PACKAGE_ADDED intent, and calls onContentChanged() on the particular   // Loader whenever the receiver detects that a new application has been installed.  // Please don’t hesitate to leave a comment if you still find this confusing! :)  private SampleObserver mObserver;}