Question

I have wrote an app to run an AsyncTask and part of the code is listed as follow. The problem is when the AsyncTask start by execute the code – “new AddImageTask().execute();” in the thread handler, the task will start and everything seems right. However, eventually the app will stay in “doInBackground” method after all code in “doInBackground” method has been executed. The task can’t go to “onPostExecute” method. (i.e. can’t dismiss the dialog…) What get wrong?

Thanks for the help……

private Handler handleFetchResult = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        progressDialog.dismiss();
        Log.d(TAG, "Start handle fetch result");
        try {
            JSONArray ja = new JSONArray(fetchResult);
            Log.d(TAG, "JSON Array Length = " + ja.length());
            JSONObject jo = new JSONObject();

            for (int i = 0; i < ja.length(); i++) {
                jo = ja.getJSONObject(i);
                PhotoURLs.add(PAT_url + jo.getString("filePath"));
                Log.d(TAG, PhotoURLs.get(i));
            }
        } catch (JSONException e) {
            Log.d(TAG, "Fetch result error: " + e.getLocalizedMessage());
            e.printStackTrace();
        }

        //TODO: display thumbnail
        new AddImageTask().execute();

    }//void handleMessage
};//Handler handleFetchResult


class AddImageTask extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        loadThumbnailDialog.show(SitePhotoGallery.this, "Fetch thumbnails from server",
                "Loading...", true, true);
        Log.d("AddImageTask.onPreExecute","onPreExecute");
    }
    @Override
    protected Void doInBackground(Void... unused) {
        // TODO Auto-generated method stub
        for (String url : PhotoURLs) {

            String filename = url.substring(url.lastIndexOf("/") + 1, url.length());

            String thumburl = url.substring(0, url.lastIndexOf("/")+1);



            imgAdapter.addItem(LoadThumbnailFromURL(thumburl + filename));
            publishProgress();

        }
        Log.d("AddImageTask.doInBackground","doInBackground");
        return null ;
    }

    @Override
    protected void onProgressUpdate(Void... unused) {
        super.onProgressUpdate();
        imgAdapter.notifyDataSetChanged();
        Log.d("AddImageTask.onProgressUpdate","OnProgressUpdate");

    }

    protected void onPostExecute(Void... unused) {
        super.onPostExecute(null);
        loadThumbnailDialog.dismiss();
        Log.d("AddImageTask.onPostExecute","onPostExecute");

    }

}

Answer 1

I think it’s because onPostExecute() should take a Void parameter and not a Void... parameter. (You should also specify @Override as Soxxeh pointed out in his/her comment above.)