Question

I use a scheduler to ensure that my loop does not take too long, so I exit the loop if the scheduler fires and ends the loop.

This is quite straight forward:

public void startSchedulerForTimeout() {

    Log.i("x", "SCHEDULING TIMEOUT " );
    timeoutForLoopReached = false;
    scheduler.schedule(new Runnable() {
    public void run() {
        timeoutForLoopReached = true;
        Log.i("x", "SET TIMEOUT FLAG ");
        }
     }, 10, TimeUnit.SECONDS);
}

so in my code I just write:

startSchedulerForUSBMessageTimeout();
while (!done && !timeoutForLoopReached) {
  ...do the loop stuff
}

To make sure that the scheduled task does not fire when I run the loop again I need to unschedule the obsolete task (in case I ended the loop before timeout) so that the new timer will start again at the beginning of a new loop (instead of the old one firing after the first loop has been finished right in between the second time the loop executes)

How can I just unschedule any scheduled task that has not been fired to avoid this scheduled task mixup?

Many thanks!

Answer 1

Use ScheduledFuture:

ScheduledExecutorService scheduledTaskExecutor = Executors.newScheduledThreadPool(1);
Runnable longRunningTask = new Runnable();

// schedule long running task in 2 minutes:
ScheduledFuture scheduleFuture = scheduledTaskExecutor.schedule(longRunningTask, 2, TimeUnit.MINUTES);

... ...
// At some point in the future, if you want to cancel scheduled task:
scheduleFuture.cancel(true);
... ...