async task not running when called from other async task

Question

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

@Override
protected void onPreExecute() {
    v.findViewById(R.id.loadinglayout).setVisibility(View.VISIBLE);
    v.findViewById(R.id.wholecontentlayout).setVisibility(View.INVISIBLE);
    super.onPreExecute();
}

@Override
protected Void doInBackground(Void... voids) {
    callAPI();
    return null;
}

@Override
protected void onPostExecute(Void aVoid) {
    super.onPostExecute(aVoid);
    v.findViewById(R.id.loadinglayout).setVisibility(View.INVISIBLE);
    v.findViewById(R.id.wholecontentlayout).setVisibility(View.VISIBLE);
}
}



public void callAPI ()
{
    RequestInterface requestInterface = new RequestImplementation();
    requestInterface.setUrl("https://api.myjson.com/bins/vl9pp");
    ConnectionExecutor connectionExecutor = new 
    ConnectionImplementation();
    ResponseInterface temp = null;
    try {
       temp = connectionExecutor.executeConnection(requestInterface);
    } catch (InterruptedException e) {
       e.printStackTrace();
    } catch (ExecutionException e) {
       e.printStackTrace();
    }
   rangeText.setText(temp.getPayload());
}

Call API function will call a method of another class where HttpConnection is done.

If the function is directly called from onViewCreated() in fragment then it works. If I call it from another async task it returns nothing.

I am actually trying to show a progress bar when the callApi function is called.

Can you post the code from where are you calling it from another asynctask? — fluffyBatman, Aug 23 '17 at 10:17
You calling TestAsync class right .. Can you show that code? — SARATH V, Aug 23 '17 at 10:26
Yeah sure ! I am calling TestAsync. But when I call calAPI directly it works. — Abhishek Veenakkat, Aug 23 '17 at 10:28
@fluffyBatman I am calling an implementation from this callAPI — Abhishek Veenakkat, Aug 23 '17 at 10:29

score 0 · Answer 1 · answered Aug 23 '17 at 10:19

0

call it on onPostExecute method

@Override
 protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
v.findViewById(R.id.loadinglayout).setVisibility(View.INVISIBLE);
v.findViewById(R.id.wholecontentlayout).setVisibility(View.VISIBLE);
  callAPI();
}}

answered Aug 23 '17 at 10:19

Ramees

68
4
16

Let me try..But I guess I wont be able to show a progress bar while loading doing so. – Abhishek Veenakkat Aug 23 '17 at 10:29
Calling from onPostExecute works !! But I need it to be done in the background :( – Abhishek Veenakkat Aug 23 '17 at 10:32
I dont think it is possible to do that in doInBackground....You cannot do anything which changes interface in doInBackground – Ramees Aug 23 '17 at 17:04

score 0 · Accepted Answer · edited Jun 20 '20 at 09:12

0

It is not allowed to start an AsyncTask outside the UI thread. doInBackground is outside the UI thread.

From https://developer.android.com/reference/android/os/AsyncTask.html:

Threading rules

...

The AsyncTask class must be loaded on the UI thread.

edited Jun 20 '20 at 09:12

Community

1
1

answered Aug 23 '17 at 10:37

k3b

14,517
7
53
85

Then how can I show a progress bar while callAPI is called ? – Abhishek Veenakkat Aug 23 '17 at 10:52

score 0 · Answer 3 · answered Aug 23 '17 at 10:37

From this SO answer

only inside onProgressUpdate() or onPostExecute() since these methods runs on the UI thread. Therefore, start the second AsyncTask on the UI thread by choosing one of the two methods listed above.

Simply put, if you're in need of firing up AsyncTask within another AsyncTask, it must be called from either onProgressUpdate() or onPostExecute() since they resides in UI thread.

score 0 · Answer 4 · answered Aug 23 '17 at 11:55

To show the ProgressBar to illumilate the task is running, you should show your progress bar in onPreExecute() and hide it in onPostExecute(Result).

 AsyncTask<Void, Void, Void> yourTask = new AsyncTask<Void, Void, Void>() {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        /**
         * Show your progress bar:
         */
        yourProgressBar.setVisibility(View.VISIBLE);

    }

    @Override
    protected Void doInBackground(Void... params) {
        /**
         * Do your stuffs in background thread
         */
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        /**
         * Hide your progress bar:
         */
        yourProgressBar.setVisibility(View.GONE);
    }
};

Run the task: yourTask.execute();

onPostExecute(Result) method will get called when the task completed.

async task not running when called from other async task

4 Answers4