public class CountDownLatch {
public static void main(String[] args) throws Exception{
java.util.concurrent.CountDownLatch countDownLatch = new java.util.concurrent.CountDownLatch(6);
for(int i=1;i<=6;i++){
new Thread(()->{
System.out.println(Thread.currentThread().getName()+" 上完自习，离开教室");
countDownLatch.countDown();
},String.valueOf(i)).start();
}
countDownLatch.await();
System.out.println(Thread.currentThread().getName()+" *****班长最后关门走人");
}
}