Where do I create and use ScheduledThreadPoolExecutor, TimerTask, or Handler?

Question

I need to make my RSS Feed reader check the feed every 10 minutes for new posts, and then parse them if there are new ones. I also need to update the UI about every minute.

I have read and heard different things from various sources. My current understanding is that I can use ScheduledThreadPoolExecutor to make two scheduled threads, and one of them needs a Handler for updating the UI. I am unsure about what the most efficient use of these classes or TimerTask.

I am also very uncertain about where to make subclasses of these. One friend suggested extending TimerTask as an inner class in my FeedParser class to make it simpler. However, to implement it in that way, I have to use the run() method for TimerTask without overriding it, meaning I can't simply use the parameters I need for the functions that need to run.

In short, what is the best way to schedule the tasks for this, and where would I implement these?

score 55 · Accepted Answer · answered Nov 12 '11 at 04:08

55

I prefer to use ScheduledThreadPoolExecutor. Generally, if I understand your requirements correctly, all these can be implemented in your activity, TimerTask and Handler are not needed, see sample code below:

public class MyActivity extends Activity {
  private ScheduledExecutorService scheduleTaskExecutor;

  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    scheduleTaskExecutor= Executors.newScheduledThreadPool(5);

    // This schedule a task to run every 10 minutes:
    scheduleTaskExecutor.scheduleAtFixedRate(new Runnable() {
      public void run() {
        // Parsing RSS feed:
        myFeedParser.doSomething();

        // If you need update UI, simply do this:
        runOnUiThread(new Runnable() {
          public void run() {
            // update your UI component here.
            myTextView.setText("refreshed");
          }
        });
      }
    }, 0, 10, TimeUnit.MINUTES);
  } // end of onCreate()
}

Remember to finish/close your runnable task properly in Activity.onDestroy(), hope that help.

answered Nov 12 '11 at 04:08

yorkw

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So is it preferred to actually use `ScheduledExecutorService` rather than `ScheduledThreadPoolExecutor`, which is a subclass of the former? Or is it just that I don't need the added things in `ScheduledThreadPoolExecutor`? – zr00 Nov 14 '11 at 15:51
2

As you said, ScheduledThreadPoolExecutor is a ScheduledExecutorService, which one to use is totally up to you. – yorkw Nov 14 '11 at 19:14
5

Very helpful answer, how do you go about "finishing/closing your runnable task properly" all the examples I found used a handler/timer to accomplish this and removeCallbacks. Anyone know the process for ScheduledThreadPoolExecutor? – Jacob McKay Nov 14 '14 at 08:57
I am trying this method out for a periodic task, but it does not seem to work http://stackoverflow.com/questions/27872016/scheduledthreadpoolexecutor-for-a-periodic-task-using-retrofit-just-firing-onc – dowjones123 Jan 10 '15 at 01:59
Thank you so much for this answer, worked for me. Just one issue, is it possible to suspend the UI updates in `onPause()` to avoid queueing up numerous UI updates (in my case `alertDialog`). – Emzor Jan 08 '16 at 23:40

Where do I create and use ScheduledThreadPoolExecutor, TimerTask, or Handler?

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