Invoking "this.notify()" before thread exit?

Question

a Runnable class that i am writing must account for 2 cases:
(1) the user wants to do other work while the Runnable does its business.
(2) the user wants to wait for the Runnable to exit before continuing on with other work.
this is my best solution:
MyRunnable mr = new MyRunnable();
new Thread(mr).start();
synchronized(mr) {
  mr.wait();
public class MyRunnable implements Runnable {
  public void run() {
    synchronized(this) {
      this.notifyAll(); // just before exit, i notify everyone that i am exiting. but if no one is waiting, what harm does this do?
} further, why not do this.notifyAll() for all Threads / Runnables just before they exit?
if no one is waiting, is there harm in invoking notifyAll() ? seems that this just adds a new feature to my class at no cost??
my understanding of OOP is that a class writer should not assume how a user will use his class, so this seems like a good option. yet, this does seem non-standard.
Edited by: kogose on Oct 19, 2008 11:53 AM

Answer 1

But why start a thread at all only to wait for it? In the case where the caller wants to wait, he should just call your run() method directly. No other code required. In the case where he wants to proceed independently, he can call new Thread(xxx).start().