Android: example implementation of Loader for generics

AsyncGenericLoader.java

/**
 * An {@link AsyncTaskLoader} implementation for loading objects like entities, cursors, etc.
 * which takes care of delivering and reseting results. For Cursors you need to override
 * onReleaseResources and perform all kind there, e.g. call close() method.
 */
public abstract class AsyncGenericLoader<T> extends AsyncTaskLoader<T> {

    protected T mItems;

    public AsyncGenericLoader(final Context context) {
        super(context);
    }

    /**
     * Called when there is new data to deliver to the client.  The
     * super class will take care of delivering it.
     */
    @Override
    public void deliverResult(final T items) {
        if (isReset()) {
            // An async query came in while the loader is stopped. We
            // don't need the result.
            if (items != null) {
                onReleaseResources(items);
            }
        }

        mItems = items;

        if (isStarted()) {
            // If the Loader is currently started, we can immediately
            // deliver its results.
            super.deliverResult(items);
        }

        // At this point we can release the resources associated with
        // 'items'; now that the new result is delivered we
        // know that it is no longer in use.
        if (items != null) {
            onReleaseResources(items);
        }
    }

    /**
     * Handles a request to start the Loader.
     */
    @Override
    protected void onStartLoading() {
        if (mItems != null) {
            // If we currently have a result available, deliver it
            // immediately.
            deliverResult(mItems);
        } else {
            forceLoad();
        }
    }

    /**
     * Handles a request to stop the Loader.
     */
    @Override
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    @Override
    public void onCanceled(final T items) {
        super.onCanceled(items);

        // At this point we can release the resources associated with 'apps'
        // if needed.
        onReleaseResources(items);
    }

    /**
     * Handles a request to completely reset the Loader.
     */
    @Override
    protected void onReset() {
        super.onReset();

        onStopLoading();

        if (mItems != null) {
            onReleaseResources(mItems);
            mItems = null;
        }
    }

    /**
     * Helper function to take care of releasing resources associated
     * with an actively loaded data set.
     */
    protected void onReleaseResources(final T items) {
        // For a simple List<> there is nothing to do.  For something
        // like a Cursor, we would close it here.
    }
}