Concurrency and restarting tasks

me 2 <>
Tue, 26 Feb 2013 06:32:28 -0800 (PST)

I have an interesting (to me at least!) puzzle.

I have a task that can take a long time that I need to run periodically. I=
 want to be able to cancel the execution of that task. I've been looking a=
t the Scheduler and Future objects, but I haven't seen how to cleanly stop,=
 wait for a couple of seconds and restart the task on schedule. And my tas=
k won't always take X seconds--sometimes it will generate exceptions or tak=
e longer or shorter or any number of other things.

Right now I have:

        final Runnable beeper = new Runnable()
            public void run()
                System.out.println("beep -- doing long task");
                //doing long task
                System.out.println("finished doing long task");

            ScheduledFuture<?> beeperHandle;
            try {
                beeperHandle = scheduler.scheduleAtFixedRate( beeper, 1, 2, SECONDS);
                beeperHandle.get(3, SECONDS);
            } catch (TimeoutException te) {
                System.out.println("Canceled due to timeout");
            } catch (InterruptedException | ExecutionException e) {
                // TODO Auto-generated catch block

There are plenty of examples that show the first steps--setting up the sche=
dule and canceling. Restarting apparently is not as common.

Any ideas would be fantastic.
Thank you,

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