Java - Running a thread twice [closed]

Question

From another post:

If a Thread needs to be run more than once, then one should make an new instance of the Thread and call start on it.

How is this done?

Answer 1

I would use another layer of abstraction. Use an ExecutorService.

Here is a simple example:

public static void main(String args[]) throws InterruptedException {
    final ExecutorService service = Executors.newCachedThreadPool();
    final class MyTask implements Runnable {

        @Override
        public void run() {
            System.out.println("Running my task.");
        }
    };
    for (int i = 0; i < 10; ++i) {
        service.submit(new MyTask());
    }
    service.shutdown();
    service.awaitTermination(1, TimeUnit.DAYS);
}

Just dump your task into the service as many times as you want.

The ExecutorService is a thread pool - it has a number of Threads that take tasks as they come. This removes the overhead of spawning new Threads because it caches them.

Answer 2

Basically, a thread cannot be restarted.

So if you want a reusable "thread", you are really talking about a Runnable. You might do something like this:

  Runnable myTask = new Runnable() {
      public void run() {
          // Do some task
      }
  }

  Thread t1 = new Thread(myTask);
  t1.start();
  t1.join();
  Thread t2 = new Thread(myTask);
  t2.start();

(This is purely for illustration purposes only! It is much better to run your "runnables" using a more sophisticated mechanism, such as provided by one of the ExecutorService classes, which is going to manage the actual threads in a way that avoids them terminating.)