package com.multithread.cyclicbarrier;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import com.multithread.main.ExampleInterface;public class CyclicBarrierExample extends ExampleInterface {    @Override    public void startDemo() {         System.out.println("开始线程："+Thread.currentThread().getId());        // TODO Auto-generated method stub        final CyclicBarrier barrier = new CyclicBarrier(3, new Runnable() {            /*             * 运行在最后一个await到达的线程，不是主线程！             * */            @Override            public void run() {                System.out.println("所有选手ready"+"线程："+Thread.currentThread().getId());            }        });                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")));            executor.shutdown();    }}package com.multithread.cyclicbarrier;import java.util.Random;import java.util.concurrent.BrokenBarrierException;import java.util.concurrent.CyclicBarrier;public 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;      }        @Override      public void run() {          try {              Thread.sleep(1000 * (new Random()).nextInt(8));              System.out.println(name + " 准备好了..."+"线程："+Thread.currentThread().getId());              // 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！"+"线程："+Thread.currentThread().getId());      }  }