How to cancel AsyncTask when Activity finishes?

Question

In my Activity I use multiple AsyncTask classes.

How to cancel AsyncTask when Activity finishes?

Answer 1

I don't understand if your "cancel" means rollback but you have a cancel method on the AsyncTask class.

Answer 2

i think the best place to do this is onStop

protected void onStop() {
    super.onStop();

    /*
    * The device may have been rotated and the activity is going to be destroyed
    * you always should be prepared to cancel your AsnycTasks before the Activity
    * which created them is going to be destroyed.
    * And dont rely on mayInteruptIfRunning
    */
    if (this.loaderTask != null) {
        this.loaderTask.cancel(false);
    }
}

in my Task i then check as often as possible if cancel was called

protected String doInBackground(String... arg0) {
    if (this.isCancelled()) {
        return null;
    }
}

and of course dont forget to drop data that maybe returned since there's no more Activity to receive it

protected void onPostExecute(List<UserStatus> result) {
    if(!this.isCancelled()) {
        //pass data to receiver
    }
}

Answer 3

The asynctask thread is kept alive in a thread pool for future istances of AsyncTask. You can't remove them.