写两个线程，交替打印数字和字母，一个线程打印 1~26，另一个线程打印字母 A-Z

Posted 2022-12-06 旺仔哥

• 1.使用synchronized

    public static void main(String[] args) 
        new Thread(new MyThread(),"p1").start();
        new Thread(new MyThread(),"p2").start();
    
static class MyThread implements Runnable
     public MyThread() 
         super();
     

     @Override
     public void run() 

         synchronized (MyThread.class)
             for (int i = 0; i < 26; i++) 
                 if (Thread.currentThread().getName().equals("p1")) 
                     System.out.print(i+1);
                     MyThread.class.notifyAll();
                     try 
                         MyThread.class.wait();
                      catch (InterruptedException e) 
                         e.printStackTrace();
                     

                  else 
                     System.out.print((char)('A'+i));
                     MyThread.class.notifyAll();
                     try 
                         MyThread.class.wait();
                      catch (InterruptedException e) 
                         e.printStackTrace();
                     

                 
             

         

     
 

 

• 2.使用信号量Semaphore实现

  static Semaphore sp1 = new Semaphore(1);
  static Semaphore sp2 = new Semaphore(1); 
  
  public static void main(String[] args) throws InterruptedException 
  
         sp2.acquire();
         new Thread(new MyThread1(sp1,sp2),"p1").start();
         new Thread(new MyThread2(sp1,sp2),"p2").start();
      
  static class MyThread1 implements Runnable
      private Semaphore sp1;
      private Semaphore sp2;
  
      public MyThread1(Semaphore sp1,Semaphore sp2) 
          super();
          this.sp1 = sp1;
          this.sp2 = sp2;
  
      
  
      @Override
      public void run() 
  
  
          try 
              sp1.acquire();
              for (int i = 0; i < 26; i++) 
                      System.out.print(i);
                      sp2.release();
                      sp1.acquire();
  
  
                  // TimeUnit.SECONDS.sleep(3);
  
              
           catch (InterruptedException e) 
              e.printStackTrace();
          finally 
  
  
          
  
  
      
  
  
  static class MyThread2 implements Runnable
      private Semaphore sp1;
      private Semaphore sp2;
  
      public MyThread2(Semaphore sp1,Semaphore sp2) 
          super();
          this.sp1 = sp1;
          this.sp2 = sp2;
  
      
  
      @Override
      public void run() 
          try 
              sp2.acquire();
  
              for (int i = 0; i < 26; i++) 
  
                  System.out.print((char)('A'+i));
                  sp1.release();
                  sp2.acquire();
  
                  // TimeUnit.SECONDS.sleep(3);
  
              
           catch (InterruptedException e) 
              e.printStackTrace();
          finally