I'm trying to implement a list/detail workflow where a tap on a list item causes the detail section to load data related to the newly selected row. I'm trying to use an AsyncTaskLoader
to accomplish this. I'm running into a problem where if I tap three list items quickly enough in a row, only two of the loads actually occur and the third gets lost.
I've written a sample activity that demonstrates this behavior. When tapping the button three times, the loadInBackground()
method is only getting called twice. Am I missing a call somewhere?
public final class LoaderActivity extends Activity implements LoaderManager.LoaderCallbacks<Integer> {
private Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.loader);
button = (Button) findViewById(R.id.load_button);
getLoaderManager().initLoader(0, null, this);
}
public void onButtonClick(View source) {
Loader<Integer> loader = getLoaderManager().getLoader(0);
if (loader != null) {
loader.forceLoad();
}
}
@Override
public Loader<Integer> onCreateLoader(int id, Bundle args) {
return new IntLoader(this);
}
@Override
public void onLoadFinished(Loader<Integer> listLoader, Integer data) {
button.setText(String.valueOf(data));
}
@Override
public void onLoaderReset(Loader<Integer> listLoader) {
}
private static final class IntLoader extends AsyncTaskLoader<Integer> {
private static final AtomicInteger counter = new AtomicInteger(0);
IntLoader(Context context) {
super(context);
}
@Override
public Integer loadInBackground() {
int result = counter.getAndIncrement();
// Simulate a potentially expensive web call
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
}
return result;
}
@Override
protected void onStopLoading() {
cancelLoad();
}
@Override
protected void onReset() {
onStopLoading();
}
@Override
public void deliverResult(Integer data) {
if (isStarted()) {
super.deliverResult(data);
}
}
}
}
Calling restartLoader(0, null, this)
instead of getLoader(0)
in the onButtonClick()
method seems to have solved this problem. As I'm learning more about Loader
s it sounds like the more appropriate method to call since I'm wanting to discard any old results at that point.