线程全部结束与集合点

final int size = 50;final CountDownLatch countDown = new CountDownLatch(size);//执行计数final CyclicBarrier barrier = new CyclicBarrier(size);    //集合点ExecutorService exec = Executors.newFixedThreadPool(size);   long start = System.currentTimeMillis();for(int index=1; index <= size; index++ ){      final int indexCopy = index;       Runnable run = new Runnable() {           public void run() {               try {                       System.out.println(indexCopy+"号就绪!");                       barrier.await();//等待所有线程集合                       System.out.println(indexCopy+"号开始执行!");               } catch (Exception e) {                       e.printStackTrace();               }               finally{                   countDown.countDown();//释放               }           }       };       exec.execute(run);      }     countDown.await();//等待线程完成   exec.shutdown();    //统计时间   System.out.println("结束时间："+sdf.format(endDate));