How do I cancel an AsyncTask

I am using an Asynctask as the loop controller for a game and noticed that the thread created kept on running after the activity was finished.

I realised that was the correct behavio开发者_运维问答ur of a separate thread and then I tried hunting down answers on how to end the thread when the app enters onPause.

I found lots of similar questions but no direct answers but eventually came up with a method so I'm going to answer my own question here to hopefully help others in future. (And to receive improvements to my answer as well)

Firstly, AsyncTask have a fully valid cancel() method. Secondly, do not use an AsyncTask for a proper game loop. AsyncTask isn't for long-running operations.

Therefore, skip AsyncTask for your game loop and learn how to properly manage pausing / resuming in an ordinary Thread by reading another answer from me here on SO.

public class CamOverlayTest extends Activity {
//...
public static BackgroundLoop BackgroundLoopTask;
//...

@Override
protected void onResume() {
    //...

    BackgroundLoopTask = new BackgroundLoop();
    BackgroundLoopTask.execute();


}

@Override
protected void onPause() {
    //...
    BackgroundLoopTask.cancel(true);
}

private class BackgroundLoop extends AsyncTask<Void,Integer,Boolean> {

    @Override
    protected Boolean doInBackground(Void... arg0) {
        int count =0;

        while (!this.isCancelled()) {
        // Basically, this is where the loop checks if the Aysnctask has been asked to be
        // cancelled - if so - it exits.
            try {
                Thread.sleep(1000);
                updatePhysics(count);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            count +=1;
            Log.i("SW","Count: "+count);
            publishProgress();

        }
        return true;
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        // swDrawOnTop is my view 
        swDrawOnTop.invalidate();
    }
//...

}