Wait/Notify in Java

public class Object {

void notify(); /* signal */

void notifyAll(); /* broadcast */

void wait();

void wait(long timeout);

}

public class PingPong (extends Object) {

public synchronized void PingPong() {

while(true) {

notify();

wait();

}

}

}

Every Java object may be treated as a condition variable for threads using its monitor.

A thread must own an object’s monitor to call wait/notify, else the method raises an IllegalMonitorStateException.

Wait(*) waits until the timeout elapses or another thread notifies, then it waits some more until it can re-obtain ownership of the monitor: Mesa semantics.

Loop before you leap!

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