Message queue like in C++ threads

Question

Hi,
I have a question. Does java support threads sending messages to each other like in C++ threads on Windows?
On Win32, a thread sends message to another thread. This message gets queued up in a message queue, I think, by the OS. The receiver thread can Peek or Get a message from the message queue by doing a such a request.
Thanks.
Tri

Answer 1

That code does not check my "claim". You never directly modify the list in that code. This code does verify my "claim" ... lol
import java.util.*;
public class test {
public static void main(String[] args) {
  List list = new LinkedList();
  list.add(new Object());
  Iterator itr = list.iterator();
  list.add(new Object());
  itr.next();
}Save compile it.. run it... you'll get ConcurrentModificationException. This isn't a "claim" of mine. Iterators in java are what's called "Fail Fast". This means if you directly modify the underlying collection, then try to use the iterator again, it fails, in java with an Exception.
In your code you posted above you had a "list.add(p);" that's a direct modification of the list. Once that happens, all iterators are invalid, and will throw an exception if used. With more then one thread this can get kinda weird. That's why Doug Lea has created the util.concurrent package. Check out the read write locks. You can put them over a collection with just a few lines of code. Much faster then fully synchronized collections. This package will appear in java version 1.5 ... check out JSR 166. Links inside the site below.. for more info.
http://g.cs.oswego.edu