Greetings!
I am trying to make a simple thread/conncurrency example work.
What I am trying to do in the following simple code example is:
1. Start a thread
2. Make the started thread become another object's (String s)  monitor
by executing a synchronized() statement
3. Call wait().
But it fails with an IllegalMonitorStateException.
If I understand the documentation correctly, I am under impression that
if the code within the synchronized() {} block is executing, the thread
is already the monitor of the object it's synchronizing on,  but that
seems not to be the case :(
The following simple program fails, and I can't figure out what's
wrong. I must be missing something simple.

import java.util.*;

public class Foo extends Thread
{
 private String s;
 public Foo(String ss) { s = ss; }

 public void run()
 {
   synchronized(s) // changing this line to 'synchronized(this)' fixes
the problem
   {
     try
     {
       wait();
     }
     catch(InterruptedException e)
     {
       System.err.println(e);
       System.exit(1);
     }
   }
 }

 public static void main(String[] args)
 {
   new Foo("abc").start();
 }
}

Running the above produces this:
Exception in thread "Thread-0" java.lang.IllegalMonitorStateException
       at java.lang.Object.wait(Native Method)
       at java.lang.Object.wait(Object.java:474)
       at Foo.run(Foo.java:14)

my java version is:
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)

Any suggestions will be very much appreciated.