How to call a thread to run on specific time in java?

Question

I want o make threads execute at specific exact times (for example at: 2012-07-11 13:12:24 and 2012-07-11 15:23:45)

I checked ScheduledExecutorService, but it only supports executing after specific period from the first run and I don't have any fixed periods, instead I have times from database to execute tasks on.

In a previous question for a different problem here, TimerTask was the solution, but obviuosly I can't make thread a TimerTask as Runnable and TimerTask both have the method run which needs to be implemented. The question here if I make the thread extends TimerTask and have one implementation of run(), would that work? If not, then how it's possible to do what I'm trying to do?

Answer 1

Use TimerTask .

Create a TimerTask object with a field variable as your thread. Call the Thread start from the Timer task Run method.

public class SampleTask extends TimerTask {
  Thread myThreadObj;
  SampleTask (Thread t){
   this.myThreadObj=t;
  }
  public void run() {
   myThreadObj.start();
  }
}

Configure it like this.

Timer timer  new Timer();
Thread myThread= // Your thread
Calendar date = Calendar.getInstance();
date.set(
  Calendar.DAY_OF_WEEK,
  Calendar.SUNDAY
);
date.set(Calendar.HOUR, 0);
date.set(Calendar.MINUTE, 0);
date.set(Calendar.SECOND, 0);
date.set(Calendar.MILLISECOND, 0);
// Schedule to run every Sunday in midnight
timer.schedule(
  new SampleTask (myThread),
  date.getTime(),
  1000 * 60 * 60 * 24 * 7
);

Answer 2

I think you should better use some library like the Quartz Scheduler. This is basically an implementation of cron for Java.

Answer 3

Have you looked at CountDownLatch from the java.util.concurrent package? It provides a count down then triggers the thread(s) to run. I never needed to use it myself, but have seen it in use a couple times.