1、 有4个线程A、B、C、D，分别打印1、2、3、4，请同时启动他们，但是要求按照1234的顺序输出结果。

public class TestABCThread3 {

private Object lock = new Object();

private int count;

public static void main(String[] args) {

TestABCThread3 abc = new TestABCThread3();

new Thread(abc.new Run("C", 3)).start();

new Thread(abc.new Run("D", 4)).start();

new Thread(abc.new Run("A", 1)).start();

new Thread(abc.new Run("B", 2)).start();

}

class Run implements Runnable {

private String _name = "";

private int _threadNum;

public Run(String name, int threadNum) {

_name = name;

_threadNum = threadNum;

}

@Override

public void run() {

synchronized (lock) {

while (true) {

if (count % 4 == _threadNum - 1) {

System.out.println("Thread-Name:" + _name+",No:"+this._threadNum);

count++;

lock.notifyAll();

break;

} else {

try {

lock.wait();

} catch (InterruptedException e) {

e.printStackTrace();

}

}

}

}

}

}

}