public class UserCountDownLatch {  static CountDownLatch latch = new CountDownLatch(6);  //初始化線程  private static class InitThread implements Runnable{    @Override    public void run() {      System.out.println("Thread_"+Thread.currentThread().getId()+" ready init work ...");      latch.countDown();//初始化線程完成工作了?？垡淮?/code>    }  }  public static void main(String[] args) throws InterruptedException {    //單獨(dú)的初始化線程,初始化分為2步，需扣減兩次    new Thread(new Runnable() {      @Override      public void run() {        try {          Thread.sleep(1000);          System.out.println("Thread_"+Thread.currentThread().getId()              +" ready init work step lst.....");          latch.countDown();//每完成一步工作，就扣減一次          System.out.println("begin step 2nd......");          Thread.sleep(1000);          System.out.println("Thread_"+Thread.currentThread().getId()              +" ready init work step 2nd.....");          latch.countDown();//每完成一步工作，就扣減一次        } catch (InterruptedException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }
      }    }).start();    for(int i=0;i<=3;i++){      Thread thread = new Thread(new InitThread());      thread.start();    }    latch.await();    System.out.println("Main do ites work ....");  }}

Thread_14 ready init work ...Thread_12 ready init work ...Thread_11 ready init work ...Thread_13 ready init work ...Thread_10 ready init work step lst.....begin step 2nd......Thread_10 ready init work step 2nd.....Main do ites work ....

public class UseCyclicBarrier {  private static CyclicBarrier barrier =       new CyclicBarrier(5,new CollectThread());//屏障開(kāi)放后，CollectThread()就會(huì)執(zhí)行.    private static ConcurrentHashMap<String, Long> resultMap =       new ConcurrentHashMap<String, Long>();//存放子線程工作結(jié)果的容器    public static void main(String[] args){    for(int i=0;i<=4;i++){      Thread thread = new Thread(new SubThread());      thread.start();    }  }  //負(fù)責(zé)屏障開(kāi)放以后的工作  private static class CollectThread implements Runnable{    @Override    public void run() {      StringBuilder result = new StringBuilder();      for(Map.Entry<String, Long> workResult:resultMap.entrySet()){        result.append("["+workResult.getValue()+"]");      }            System.out.println("the result = "+result);      System.out.println("do other business......");    }    }  //工作線程  private static class SubThread implements Runnable{    @Override    public void run() {      long id = Thread.currentThread().getId();      resultMap.put(Thread.currentThread().getId()+"", id);      Random r = new Random();//隨機(jī)決定工作線程的是否睡眠      try{        if(r.nextBoolean()){            Thread.sleep(2000+id);            System.out.println("Thread_"+id+".....do its business ");          }          System.out.println(id+".....is await");          barrier.await();//          Thread.sleep(1000+id);          System.out.println("Thread_"+id+".....do its business ");        }catch(Exception e){          e.printStackTrace();        }      }    }  }