CountDownLatch 和 CyclicBarrier 的区别

CountDownLatch 属于 一个线程等待，n个线程发通知，一个线程继续往后执行，针对的是一个线程

CyclicBarrier 针对的是多个线程

CountDownLatch例子：

public class UseCountDownLatch {

	public static void main(String[] args) {

		final CountDownLatch countDown = new CountDownLatch(2);

		Thread t1 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("进入线程t1" + "等待其他线程处理完成...");
					countDown.await();
					System.err.println("t1线程继续执行...");
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}, "t1");

		Thread t2 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t2线程进行初始化操作...");
					Thread.sleep(3000);
					System.out.println("t2线程初始化完毕，通知t1线程继续...");
					countDown.countDown();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		});
		Thread t3 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("t3线程进行初始化操作...");
					Thread.sleep(4000);
					System.out.println("t3线程初始化完毕，通知t1线程继续...");
					countDown.countDown();
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		});

		t1.start();
		t2.start();
		t3.start();

	}
}

CyclicBarrier例子：

public class CyclicBarrierDemo {

	static class Runner implements Runnable {

		private CyclicBarrier barrier;
		private String name;

		public Runner(CyclicBarrier barrier, String name) {
			super();
			this.barrier = barrier;
			this.name = name;
		}

		@Override
		public void run() {
			try {
				Thread.sleep(1000 * (new Random()).nextInt(5));
				System.out.println(name + " 准备OK.");
				barrier.await();
			} catch (InterruptedException e) {
				e.printStackTrace();
			} catch (BrokenBarrierException e) {
				e.printStackTrace();
			}
			System.out.println(name + " Go!!");
		}
	}

	public static void main(String[] args) {
		CyclicBarrier barrier = new CyclicBarrier(3); // 3
		ExecutorService executor = Executors.newFixedThreadPool(3);

		executor.submit(new Thread(new Runner(barrier, "zhangsan")));
		executor.submit(new Thread(new Runner(barrier, "lisi")));
		executor.submit(new Thread(new Runner(barrier, "wangwu")));

		executor.shutdown();
	}
}