關於CountDownLatch await（）方法的問題？

Question

在我的程序中CountDownLatch的await（）方法會繼續阻塞程序，CountDownLatch就像它寫的那樣， 是倒數鎖存器，當count爲零時觸發三個Thread執行，並且證明三個時cdAnswer降爲0 線程已經執行，然後主線程執行，但在我的程序中，三個線程只完成了 這兩個主線程被執行了，誰可以幫助我，我會非常感激。 底部是我的程序。

public class CountdownLatchTest { 
    public static void main(String[] args) { 
     ExecutorService service = Executors.newCachedThreadPool(); 
     final CountDownLatch cdOrder = new CountDownLatch(1); 
     final CountDownLatch cdAnswer = new CountDownLatch(3); 

     for (int i = 0; i < 3; i++) { 
      Runnable runnable = new Runnable() { 
       @Override 
       public void run() { 
        try { 
         System.out.println("Thread" + Thread.currentThread().getName() 
           + "Wait for the command"); 

         cdOrder.await(); 
         System.out.println("Thread" + Thread.currentThread().getName() 
           + "received command"); 
         Thread.sleep((long) (Math.random() * 10000)); 
         System.out.println("Thread" + Thread.currentThread().getName() 
           + "Feedback the results"); 
         cdAnswer.countDown(); 
        } catch (Exception e) { 
         e.printStackTrace(); 
        } finally { 
         System.out.println("To complete the order"); 
         cdAnswer.countDown(); 

        } 
       } 
      }; 
      service.execute(runnable); 
     } 
     try { 
      Thread.sleep((long) (Math.random() * 10000)); 

      System.out.println("Thread" + Thread.currentThread().getName() 
        + "The upcoming orders"); 
      cdOrder.countDown(); 
      System.out.println("Thread" + Thread.currentThread().getName() 
        + "Sent the command, are waiting for the result"); 
      cdAnswer.await(); 
      System.out.println("Thread" + Thread.currentThread().getName() 
        + "Have received all the response. " 
        + "The results of this task has been completed"); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
     service.shutdown(); 

    } 
} 

問題補充： 這個結果不出我所料，我想這句話「已收到所有的響應。該任務的結果已完成'將在最後打印

圖片顯示了我的程序結果。

Answer 1

這是因爲，如果你看到運行的可運行

  public void run() { 
       try { 
        System.out.println("Thread" 
          + Thread.currentThread().getName() 
          + "Wait for the command"); 

        cdOrder.await(); 
        System.out.println("Thread" 
          + Thread.currentThread().getName() 
          + "received command"); 
        Thread.sleep((long) (Math.random() * 10000)); 
        System.out.println("Thread" 
          + Thread.currentThread().getName() 
          + "Feedback the results"); 
        cdAnswer.countDown(); -- countdown on latch cdAnswer 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } finally { 
        System.out.println("To complete the order"); 
        cdAnswer.countDown(); -- countdown on latch cdAnswer 

       } 
      } 

cdAnswer.countDown（）方法;在每個可運行的終端和catch子句之前調用兩次。 因此，三次線程倒計數被稱爲六次，結果主線程在3次倒計時後啓動。

刪除cdAnswer.countDown（）;只是在上面的聲明它按預期工作