AysncTask cancelling itself still calls onPostExecute()

Question

After calling AsyncTask.cancel(true) from within doInBackground(), instead of calling onCancelled(), Android calls onPostExecut

Answer 1

You should return null and treat the return in the onPostExecute.

Answer 2

1. There is an exception because you call cancel(true) which sends an interrupt to the thread running doInBackground() - however, in this case, you are calling cancel(true) from within doInBackground(), thus causing the thread to immediately send an interrupt to itself.

2. Your code is running on Android 2 but you are quoting the docs for Android 4. The problem is that the behaviour on cancel() changed between Android 2 and Android 4.

   Android 2.3.7 onPostExecute :

   Runs on the UI thread after doInBackground. The specified result is the value returned by doInBackground or null if the task was cancelled or an exception occured.

   Android 4.0.1 onPostExecute :

   Runs on the UI thread after doInBackground. The specified result is the value returned by doInBackground. This method won't be invoked if the task was cancelled.