AsnycTask in android

In every AsyncTask, you implement the onCancelled method:

@Override
protected void onCancelled() {
    /*Release your resources, such as closing DB connections, abort downloads in
    progress, etc*/
}

Now, calling cancel() on an AsyncTask will cause onCancelled() instead of onPostExecute() to be executed when doInBackground() is finished. Notice that onCancel isn't immediately called (as said, it's called when doInBackground is finished), but a flag is set, which can be accessed via yourAsyncTask.isCancelled(). This is why it's proper practice (and recommended by Android development guidelines) to periodically check this flag from your doInBackground method, usually in a loop:

@Override
protected Object doInBackground(Object... x) {
    while (!isCancelled()) {
      // Do your work
      return workProcessingResult;
    }
    return null;
 }

Further reading here[^]