a simple program reveal thread synchronization

Here's a simple program but reveal thread synchronization mechanism:
- only one thread can enter critical region at a fix time
- two thread enter critical region one by one, and loop
- the time won't affect thread synchronization
- two thread work together like pass ball

package com.demo.thread;

public class DemoThread {	
	public static void main(String[] args) {
		Object obj = new Object();
		
		Working worker1 = new Working("worker-1", obj, 2000);
		Working worker2 = new Working("worker-2", obj, 20);
		
		worker1.start();
		worker2.start();
	}
	
}

class Working extends Thread {
	private String mName;
	private Object mObj;
	private long mTime;
	
	public Working(String name, Object obj, long time) {
		mName = name;
		mObj = obj;
		mTime = time;
	}
	
	public void run() {
		while(true) {
			try {
				System.out.println(mName + " is waiting");
				Thread.sleep(mTime);
				System.out.println(mName + " is trying to enter critical region");
				synchronized(mObj) {
					System.out.println(mName + " has entered into critical region");
					System.out.println(mName + " will notify other thread");
					mObj.notify();
					System.out.println(mName + " will hang");
					mObj.wait();
					System.out.println(mName + " will quit critical region");
				}				
			} catch (InterruptedException e) {
				e.printStackTrace();
			}					
		}		
	}
	
}

the output will like:

worker-1 is waiting
worker-2 is waiting
worker-2 is trying to enter critical region
worker-2 has entered into critical region
worker-2 will notify other thread
worker-2 will hang
worker-1 is trying to enter critical region
worker-1 has entered into critical region
worker-1 will notify other thread
worker-1 will hang
worker-2 will quit critical region
worker-2 is waiting
worker-2 is trying to enter critical region
worker-2 has entered into critical region
worker-2 will notify other thread
worker-2 will hang
worker-1 will quit critical region
worker-1 is waiting
worker-1 is trying to enter critical region
worker-1 has entered into critical region
worker-1 will notify other thread
worker-1 will hang
worker-2 will quit critical region
worker-2 is waiting
worker-2 is trying to enter critical region
worker-2 has entered into critical region
worker-2 will notify other thread
worker-2 will hang
worker-1 will quit critical region
worker-1 is waiting
worker-1 is trying to enter critical region
worker-1 has entered into critical region
worker-1 will notify other thread
worker-1 will hang
worker-2 will quit critical region
worker-2 is waiting
worker-2 is trying to enter critical region
worker-2 has entered into critical region
worker-2 will notify other thread
worker-2 will hang
worker-1 will quit critical region
worker-1 is waiting
worker-1 is trying to enter critical region
worker-1 has entered into critical region
worker-1 will notify other thread
worker-1 will hang
worker-2 will quit critical region
worker-2 is waiting
worker-2 is trying to enter critical region
worker-2 has entered into critical region
worker-2 will notify other thread
worker-2 will hang
worker-1 will quit critical region
worker-1 is waiting
worker-1 is trying to enter critical region
worker-1 has entered into critical region
worker-1 will notify other thread
.....