Thread: How to tell when the thread is finished AND how to kill it?

Question

Hi there,
I have a thread that runs in the background and does this:
class MyThread implements Runnable 
          public void run()
               Stopper stopper = new Stopper();
                        //do something that takes some time
                        stopper.stop();
                        System.out.println("total time "+stopper.getTime());
}this works fine (I have a swing gui where I click a button and this thread runs and it's ok. PROBLEM IS, when I click the button again (to re-activate the thread) it seems that the stopper is not null but still counting the time (I was under the impression that ...= new Stopper() will create a new object type Stopper).
so -
1. How can I tell when thread is finished?
2. How do I kill this thread once it is finished?
the invocation:
     public void actionPerformed(ActionEvent arg0)
          Thread t = new Thread( new MyThread());
          t.start();          
     }THANK YOU!

Answer 1

You have not posted to code for Stopper, so it's impossible to reason about that
1. How can I tell when thread is finished?
Use Thread.Join() or Thread.isAlive()
2. How do I kill this thread once it is finished?
You can't and you don't. Just let the method the thread is running exit normally. Sometimes that means putting in a boolean variable to control a loop, and then exiting when the boolean is false.
Another thought - you could set the thread as a Daemon thread - when you don't have any non-daemon threads running, java will exit.