Android: How to update an UI from AsyncTask if AsyncTask is in a separate class?

Question

I hate inner class.

I\'ve a main activity who launches a \'short-life\' AsyncTask.

AsyncTask is in a separate file, is not an inner class of

Answer 1

I wrote a small extension to AsyncTask for this kind of scenario. It allows you to keep your AsyncTask in a separate class, but also gives you convenient access to the Tasks's completion:

public abstract class ListenableAsyncTask<Params, Progress, Result> extends AsyncTask<Params, Progress, Result>{

    @Override
    protected final void onPostExecute(Result result) {
        notifyListenerOnPostExecute(result);
    }

    private AsyncTaskListener<Result> mListener;
    public interface AsyncTaskListener<Result>{
        public void onPostExecute(Result result);
    }
    public void listenWith(AsyncTaskListener<Result> l){
        mListener = l;
    }
    private void notifyListenerOnPostExecute(Result result){
        if(mListener != null)
            mListener.onPostExecute(result);
    }

}

So first you extend ListenableAsyncTask instead of AsyncTask. Then in your UI code, make a concrete instance and set listenWith(...).