wait with/without synchronized block

[Adam Satyres]

Hi, this code is taken from K&B book :

package exercices;

public class TwoThreads {

	static Thread laurel,hardy;
	public static void main(String[] args) {
		laurel=new Thread()
		{
			@Override
			public void run() {
				System.err.println("A");
				
				try {
					hardy.sleep(1000);
				} catch (Exception e) {
					System.err.println("B");
				}
				System.err.println("C");
			}
		};
		hardy=new Thread(){
			public void run() {
				synchronized (laurel) {
					System.err.println("D"); 
					try {
						laurel.wait();
					} catch (Exception e) {
						System.err.println("E");
					}
					System.err.println("F");
					};
				}
			
		};
		laurel.start();
		hardy.start();
	}
}

when we remove synchronized we got an runtime exception because there is no synchronized object with laurel !
but when we add the synchronized block on lauref normally we got A C and then D we wait forever because there is notify from any laurel object ? am i right ?
but when we run this code we got :

A D C F

Thanks for your help!
Best regards

[Henry Wong]

Adam Satyres wrote:
but when we add the synchronized block on lauref normally we got A C and then D we wait forever because there is notify from any laurel object ? am i right ?
but when we run this code we got :

A D C F

You have a conflict with the core library. Don't use Thread objects for wait/notify -- it is used internally by the core library to implement the join() method.

Henry

[John Mercier]

Henry, what do you mean by core library?

I'm not sure why F is being printed either. I ran the code and every time F is printed.

[Henry Wong]

John Mercier wrote:Henry, what do you mean by core library?

I'm not sure why F is being printed either. I ran the code and every time F is printed.

The core library are the java classes that are included with the JVM. And the conflict that was mentioned earlier, is the reason why "F" is printed.

Henry

[dido lilo]

sometimes the jvm call the notify() methode ,but for the exam the wait should be notified