以前为公司出的一道面试题，有点偏，有兴趣的可以试试

package thread;

import java.util.LinkedList;

import org.apache.log4j.Logger;

public class ThreadWait {

	public static void main(String[] args) {
		final Logger logger = Logger.getLogger(ThreadWait.class);
		final Stack stack = new Stack();
		Thread t1 = new Thread("PopThread") {
			public void run() {
				
				logger.info(Thread.currentThread().getName()
						+ " is running....");
				Object o = null;
				try {
					o = stack.pop();
				} catch (Exception e) {
					e.printStackTrace();
				}
				logger.info("o=" + o);
				logger.info(Thread.currentThread().getName()
						+ " end....");
			}
		};
		Thread t2 = new Thread("PushThread") {
			public void run() {
				try {
					Thread.sleep(1000);
				} catch (Exception e) {
					e.printStackTrace();
				}
				logger.info(Thread.currentThread().getName()
						+ " is running....");
				stack.push(new Object());
				logger.info(Thread.currentThread().getName()
						+ " end....");
			}
		};
		t1.start();
		t2.start();
	}
}

class Stack {
	LinkedList list = new LinkedList();

	Logger logger = Logger.getLogger(Stack.class);

	public synchronized void push(Object x) {
		showThisLockOwner();
		synchronized (list) {
			showListLockOwner();
			list.addLast(x);
			notifyAll();
			logger.info("push done");
		}
	}

	public synchronized Object pop() {
		showThisLockOwner();
		synchronized (list) {
			showListLockOwner();
			while (list.size() <= 0) {
				try {
					logger.info("start list.wait(1000)");
					list.wait(1000);
					logger.info("finish list.wait(1000)");
					showThisLockOwner();
					showListLockOwner();
					logger.info("start wait(1000)");
					wait(1000);
					logger.info("finish wait(1000)");
					showListLockOwner();
					showThisLockOwner();
					logger.info("finish wait");
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
			return list.removeLast();
		}
	}
	
	public void showThisLockOwner() {
		if (Thread.holdsLock(this)) {
			logger.info("Acquired the monitor lock on this");
		}
	}

	public void showListLockOwner() {
		if (Thread.holdsLock(list)) {
			logger.info("Acquired the monitor lock on list");
		}
	}

}