package com.linux.huhx.concurreny;import java.io.IOException;
import java.util.Random;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class CyclicBarrierTest1 {public static void main(String[] args) throws IOException, InterruptedException {/*** 1、如果参数>3的话，三个线程的await执行完，parties只能加到3。那么子线程await后续的方法就不能执行* 2、如果参数=3的话，三个线程的await执行完，parties能加到3。所以子线程await后续的方法能执行* 3、如果参数<3的话，当第二个线程await执行完之后，parties加到了2。??????*/CyclicBarrier barrier = new CyclicBarrier(3);ExecutorService executor = Executors.newFixedThreadPool(3);executor.submit(new Thread(new Runner(barrier, "1号选手")));executor.submit(new Thread(new Runner(barrier, "2号选手")));executor.submit(new Thread(new Runner(barrier, "3号选手")));Thread.sleep(200);System.out.println("in main method after");executor.shutdown();}public static class Runner implements Runnable {// 一个同步辅助类，它允许一组线程互相等待，直到到达某个公共屏障点 (common barrier point)private CyclicBarrier barrier;private String name;public Runner(CyclicBarrier barrier, String name) {super();this.barrier = barrier;this.name = name;}@Overridepublic void run() {try {Thread.sleep(new Random().nextInt(1000));System.out.println(name + " 准备好了...");// barrier的await方法，在所有参与者都已经在此 barrier 上调用 await 方法之前，将一直等待。
                barrier.await();} catch (InterruptedException e) {e.printStackTrace();} catch (BrokenBarrierException e) {e.printStackTrace();}System.out.println(name + " 起跑！");}}
}

in main method after
2号选手 准备好了...
1号选手 准备好了...
3号选手 准备好了...
2号选手 起跑！
1号选手 起跑！
3号选手 起跑！