Question

I have a Runnable class that I’m writing. Inside of it, I have two methods. The run() method, and another method called stopRunning(). stopRunning() is to be called by a separate thread from the one that’s running the run() method and is to stop the thread running the run() method from running.

Here’s a code snippet:

public class myRunnable implements Runnable
{
    private boolean stillRunning = true;

    public void stopRunning()
    {
        synchronized (this)
        {
           stillRunning = false;
        }
    }

    public void run()
    {
       while (stillRunning)
       {
          synchronized (this)
          {
             // do some stuff that doesn't involve the isPlaying var
          }
       }
    }

}

Does this code look correct? Do I need to synchronize to ensure that the change of isPlaying will be recognized by the thread running the run() method?

Also, do I need to call notify() or notifyAll() anywhere here for this to work? I’m pretty sure I don’t since I never call wait(), but I’m not 100% sure.

EDIT: woops, my code was wrong. I used the wrong name for the boolean, sorry about that. It’s fixed now.

Answer 1

For the starting and stopping a thread, the Java Thread API already provides the functionality you are looking for. Thread.interrupt() and Thread.interrupted() can be used to achieve what you want.

public class MyThread extends Thread{
  public void run(){
    while(!interrupted()){
      try{
        // Place your code here
      }catch(InterruptedException e){
        break;
      }
    }
  }
}

Whenever you want to interrupt MyThread just call MyThread.interrupt()