Can AsyncTask be executed from background thread?

Question

While reading the documentation, I found that The AsyncTask class must be loaded on the UI thread. But I am surprised that AsyncTask can also be executed from the worker thread.

So the question is:

1. If AsyncTask can also execute from the background thread, Why in the documentation they are saying just opposite to it.

2. How could it possible to have context on onPostExecute.?

   new Thread(new Runnable() {
       @Override
       public void run() {
           new AsyncTask<Void, Void, Void>() {
               @Override
               protected Void doInBackground(Void... voids) {
                   return null;
               }
   
               @Override
               protected void onPostExecute(Void aVoid) {
                   super.onPostExecute(aVoid);
                   Toast.makeText(getBaseContext(), "in AsyncTask...", Toast.LENGTH_SHORT).show();
               }
           }.execute();
       }
   }).start();
   

Answer 1

The AsyncTask Android class lets us sort of bind background tasks to the UI thread. So using this class, you can perform background operations and then publish the results to the UI thread that updates the UI components.

you can understand AsyncTask execution briefly : http://codetheory.in/android-asynctask/

Answer 2

There is two Threads Main Thread and Worker Thread. Asyntasck works on worker thread.Mostly Asynctask used for background Task.It works on worker thread and publish the result on Main thread.

If Main thread block for 5 sec or more than that Application not responding (ANR) dialogs comes so to avoid this scenario for background task Asynctask used