package cm.concurrent;import java.util.concurrent.CountDownLatch;public class UseContDownLatch {	public static void main(String[] args) {        //2表示唤醒的次数，如果没有达到唤醒的次数，countDownLatch.await();之后的业务将无法执行！		final CountDownLatch countDownLatch = new CountDownLatch(2);		Thread t1=new Thread(new Runnable() {			@Override			public void run() {				try {					System.out.println("进入t1线程,等待其他线程处理完成.........");					countDownLatch.await();					System.out.println("t2和t3初始化完成,t1才能线程继续执行.................");				} catch (Exception e) {					e.printStackTrace();				}			}		},"t1");		Thread t2=new Thread(new Runnable() {			@Override			public void run() {				try {					System.out.println("进入t2线程进行初始化.........");					Thread.sleep(3000);					System.out.println("t2说：t1线程可以继续执行.................");                    //第一次唤醒					countDownLatch.countDown();				} catch (Exception e) {					e.printStackTrace();				}			}		},"t2");		Thread t3=new Thread(new Runnable() {			@Override			public void run() {				try {					System.out.println("进入t3线程进行初始化.........");					Thread.sleep(4000);					System.out.println("t3说：t1线程可以继续执行.................");                    //第二次唤醒					countDownLatch.countDown();				} catch (Exception e) {					e.printStackTrace();				}			}		},"t3");		t1.start();		t2.start();		t3.start();	}}

确切的来说，第一次唤醒和第二次唤醒并不是绝对的，因为线程中每个线程争取cpu的先后顺序都书随机的，哪个先执行，哪个就是第一次唤醒。