Stopping looping thread in Java

Question

I\'m using a thread that is continuously reading from a queue.

Something like:

public void run() {
    Object obj;
    while(true) {
        synchron         


        

Answer 1

I think your two cases actually exhibit the same potential behavior. For the second case consider Thread A adds the DeathEvent after which Thread B adds a FooEvent. When your job Thread receives the DeathEvent there is still a FooEvent behind it, which is the same scenario you are describing in Option 1, unless you try to clear the queue before returning, but then you are essentially keeping the thread alive, when what you are trying to do is stop it.

I agree with you that the first option is more desirable. A potential solution would depend on how your queue is populated. If it is a part of your work thread class you could have your stopThisThread() method set a flag that would return an appropriate value (or throw Exception) from the enqueuing call i.e.:

MyThread extends Thread{
  boolean running = true;

  public void run(){
    while(running){
      try{
        //process queue...
      }catch(InterruptedExcpetion e){
        ...
      }
    }
  }

  public void stopThisThread(){
    running = false;
    interrupt();
  }

  public boolean enqueue(Object o){
    if(!running){
       return false;
         OR
       throw new ThreadNotRunningException();
    }
    queue.add(o);
    return true;
  }
}

It would then be the responsibility of the object attempting to enqueue the Event to deal with it appropriately, but at the least it will know that the event is not in the queue, and will not be processed.