Commonly used auxiliary class

CountDownLatch

public  class CountDownLatchDemo {
     // Principle:
     // countDownLatch.countDown (); // Quantity-1
     // countDownLatch.await (); // Wait for the counter to return to zero, and then execute again
     // Every time a thread calls countDown ( ) Number -1, assuming the counter becomes 0, countDownLatch.await () will be woken up and continue to execute! 

    public  static  void main (String [] args) throws InterruptedException {
         // The total number is 6, when the task must be executed, then use 

        CountDownLatch count = new CountDownLatch ( 6 ); 

        for ( int i = 0 ; i <= 6 ; i ++) {
             new Thread (()-> { 
                System. out .println (Thread.currentThread (). getName () + " Go out " ); 
                count.countDown (); // Number minus one 
                }, String.valueOf (i )). start (); 
        } 

        count. await (); // Wait for the counter to return to 0, and then execute down 
        System. out .println ( " Close Door " );
 //         count.countDown (); 
    } 
}

CyclicBarrier

1  public  class CyclicBarrierDemo {
 2      public  static  void main (String [] args) {
 3          // If the set number is larger than the number in the loop, the dissatisfaction in the loop will be stuck in barrier.await (); wait here 
4          CyclicBarrier barrier = new CyclicBarrier ( 9 , ()-> {
 5              System. out .println ( " Summon God Dragon " );
 6          });
 7  
8  
9          for ( int i = 0 ; i <= 7 ; i ++ ) {
 10              int temp = i;
11             //lambda能操作  i 吗
12             new Thread(()->{
13                 System.out.println(Thread.currentThread().getName()+"收集"+temp+"个龙珠");
14                 try {
15                     barrier.await();
16                 } catch (InterruptedException e) {
17                     e.printStackTrace();
18                 } catch (BrokenBarrierException e) {
19                     e.printStackTrace ();
20                  }
 21              }). Start ();
22          }
 23      }
 23 }

 

Semaphore

1  public  class SemahoreDome {
 2      public  static  void main (String [] args) {
 3          // Number of threads, parking space limit will be used 
4  
5          Semaphore semaphore = new Semaphore ( 3 );
 6  
7          for ( int i = 0 ; i <= 6 ; i ++ ) {
 8              new Thread (()-> {
 9                  // acquire () gets 
10                  try {
 11                      semaphore.acquire ();
 12                     System. Out .println (Thread.currentThread (). GetName () + " Get parking space " );
 13                      TimeUnit.SECONDS.sleep ( 2 );
 14                      System. Out .println (Thread.currentThread (). GetName () + " Leave the parking lot " );
 15                  } catch (InterruptedException e) {
 16                      e.printStackTrace ();
 17                  } finally {
 18                      semaphore.release (); // release () release 
19                 }
20             },String.valueOf(i)).start();
21         }
22 
23     }
24 }