IllegalMonitorStateException doubt

[Deepak Borania]

GIven the following code :

 
public class watever{
	private static Thread t1 = new Thread("Thread1"){
		public void run(){
			synchronized (watever.class){
				try{
					wait(100);
				}catch(InterruptedException e){
					e.printStackTrace();
				}
				System.out.println ("Done");
			}
		}
	};
	public static void main(String args[]) {
    	t1.start();
    	try{
    		t1.join();
    	}catch(InterruptedException e){
    		e.printStackTrace();
    	}
	}
}
   

Can someone please tell me why does the above code result in IllegalMonitorStateException at runtime?

And please explain a little about synchronized code blocks. I just can't seem to get hang of them.

Thanks

[Rob Spoor]

You synchronize on whatever.class, then try to get the lock on "this". You can only call wait, notify and notifyAll on objects you synchronize on.