Update progressbar from AsyncTaskLoader?

Question

When using a AsyncTaskLoader how would you update a progressbar showing the status as it is being updated? Normally you wait for the callback to remove when done, but how to do

Answer 1

You can do that with loaders, but you need to keep and update a WeakReference on your Activity :

public class LoaderTestActivity extends FragmentActivity implements LoaderCallbacks {
    private static final int MAX_COUNT = 100;

    private ProgressBar progressBar;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_async_task_test);

        progressBar = (ProgressBar) findViewById(R.id.progressBar1);
        progressBar.setMax(MAX_COUNT);
        AsyncTaskCounter.mActivity = new WeakReference(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_async_task_test, menu);
        return true;
    }

    public void onStartButtonClick(View v) {
        startWork();
    }

    void startWork() {
        getSupportLoaderManager().initLoader(0, (Bundle) null, this);
    }

    static class AsyncTaskCounter extends AsyncTaskLoader {
        static WeakReference mActivity;

        AsyncTaskCounter(LoaderTestActivity activity) {
            super(activity);
            mActivity = new WeakReference(activity);
        }

        private static final int SLEEP_TIME = 200;

        @Override
        public Void loadInBackground() {
            for (int i = 0; i < MAX_COUNT; i++) {
                try {
                    Thread.sleep(SLEEP_TIME);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.d(getClass().getSimpleName(), "Progress value is " + i);
                Log.d(getClass().getSimpleName(), "getActivity is " + getContext());
                Log.d(getClass().getSimpleName(), "this is " + this);

                final int progress = i;
                if (mActivity.get() != null) {
                    mActivity.get().runOnUiThread(new Runnable() {

                        @Override
                        public void run() {
                            mActivity.get().progressBar.setProgress(progress);
                        }
                    });
                }
            }
            return null;
        }

    }

    @Override
    public Loader onCreateLoader(int id, Bundle args) {
        AsyncTaskLoader asyncTaskLoader = new AsyncTaskCounter(this);
        asyncTaskLoader.forceLoad();
        return asyncTaskLoader;
    }

    @Override
    public void onLoadFinished(Loader arg0, Void arg1) {

    }

    @Override
    public void onLoaderReset(Loader arg0) {

    }

}