Question

I have created an AsyncTask which read JSONArray in the doInBackground Method and return an ArrayList of custom Items (ArrayList). Before this, in the onPostExecute method i move the ArrayList charged in the AsyncTask to another ArrayList of the Main thread, but i think that my AsyncTask never ends and still working. Here I put my code:

Here the AsyncTask:

private class ReadJSONTask extends AsyncTask<Void, Void, ArrayList<Item>>{

        @Override
        protected ArrayList<Item> doInBackground(Void... params) {
            // TODO Auto-generated method stub
            ArrayList<Item> auxList = new ArrayList<Item>();
            LoadData(auxList); //Method that reads JSON and load information in the ArrayList
            return auxList; // Return ArrayList
        }

        @Override
        protected void onPostExecute(ArrayList<Item> result) {
            // TODO Auto-generated method stub

            Log.i("OnPostExecute", String.valueOf(result.size()));  //The size of the array
            listMain = result; // Move the data of the AsyncTask to the main Thread

            Log.i("OnPostExecute", String.valueOf(listaComic.size()));  //The size of the ArrayList I use in the Main Thread
        }

    }

Here the call to the AsyncTask in the Main Thread:

if (isOnline()){    //Return true if there is internet connection
    ReadJSONTask task = new ReadJSONTask();
    task.execute();

    Log.i("Main Thread - listMain Size", String.valueOf(listMain.size())); //Never executed

    //This for loop its only for debug purposes, never executed
    for (Item item : listMain){ 
        Log.i("Items", item.toString());
    }
}

In the log i see that all Log in the onPostExecute() method are printed, but nothing from the Main Thread.

I don’t know where is the error to fix it, i have been working on it 2 days and searching in forums, here in StackOverflow and i can’t fix that :S

Answer 1

As name indicates AsyncTask is asynchronous, but you for some reason expects execute() to be blocked unless async task ends, which is wrong. Your code works fine and I expect listMain to simply be empty and once execute() fires asynctask, for would show nothing because async task is not done yet. You should rework your app logic, so async task could tell “main thread” it finished. I.e. move your for loop to separate method and call it from onPostExecute().