public class ThreadDemo extends Thread {

private Thread t;

private String threadName;

ThreadDemo( String name) {

threadName = name;

System.out.println("Creating " + threadName );

}

@Override

public void run() {

System.out.println("Running " + threadName );

try {

for(int i = 4; i > 0; i--) {

System.out.println("Thread: " + threadName + ", " + i);

// 让线程睡眠一会

Thread.sleep(50);

}

}catch (InterruptedException e) {

System.out.println("Thread " + threadName + " interrupted.");

}

System.out.println("Thread " + threadName + " exiting.");

}

public void start () {

System.out.println("Starting " + threadName );

if (t == null) {

t = new Thread (this, threadName);

t.start ();

}

}

}