JUC包多线程之线程有序执行

Posted 2022-03-12 blog-of-zxf

想让多个线程有序执行，必须提供它们之间的唤醒机制。下面以三个线程为例，有序打印自己的线程ID

Condition condition1 = lock.newCondition();　　//代表线程1的唤醒

Condition condition2 = lock.newCondition();  　　//代表线程2的唤醒

Condition condition3= lock.newCondition();　　//代表线程3的唤醒

同时需要一个Flag作为轮到它们各自执行的条件flag=1线程1执行，不等于1则线程1进入等待唤醒

代码：

  1 package xianchengtest;
  2 
  3 import java.util.concurrent.locks.Condition;
  4 import java.util.concurrent.locks.Lock;
  5 import java.util.concurrent.locks.ReentrantLock;
  6 
  7 public class TestABCAlternate 
  8 
  9     public static void main(String[] args) 
 10         ABCAlternate as = new ABCAlternate();
 11         new Thread(new Runnable() 
 12             
 13             @Override
 14             public void run() 
 15                 for (int i = 1; i <= 10 ;i++) 
 16                     as.loopA(i);
 17                     
 18                 
 19             
 20         ,"A").start();
 21         new Thread(new Runnable() 
 22             
 23             @Override
 24             public void run() 
 25                 for (int i = 1; i <= 10 ;i++) 
 26                     as.loopB(i);
 27                     
 28                 
 29             
 30         ,"B").start();
 31         new Thread(new Runnable() 
 32             
 33             @Override
 34             public void run() 
 35                 for (int i = 1; i <= 10 ;i++) 
 36                     as.loopC(i);
 37                     System.out.println("----------------------------------");
 38                 
 39             
 40         ,"C").start();
 41 
 42     
 43 
 44 
 45 
 46 class ABCAlternate
 47     private int flag = 1;
 48     private Lock lock = new ReentrantLock();
 49     private Condition condition1 = lock.newCondition();
 50     private Condition condition2 = lock.newCondition();
 51     private Condition condition3 = lock.newCondition();
 52     
 53     public void loopA(int totaloop) 
 54         lock.lock();
 55         
 56         try 
 57             //判断
 58             if(flag != 1) 
 59                 try 
 60                     condition1.await();
 61                  catch (InterruptedException e) 
 62                 
 63             
 64             //打印
 65             for (int i = 1; i <= 1; i++) 
 66                 System.out.println(Thread.currentThread().getName() +"\t"+ i+ "\t" + totaloop);
 67             
 68             //唤醒
 69             flag = 2 ;
 70             condition2.signal();
 71          finally 
 72             lock.unlock();
 73         
 74     
 75     public void loopB(int totaloop) 
 76         lock.lock();
 77         
 78         try 
 79             //判断
 80             if(flag != 2) 
 81                 try 
 82                     condition2.await();
 83                  catch (InterruptedException e) 
 84                 
 85             
 86             //打印
 87             for (int i = 1; i <= 1; i++) 
 88                 System.out.println(Thread.currentThread().getName() +"\t"+ i+ "\t" + totaloop);
 89             
 90             //唤醒
 91             flag = 3 ;
 92             condition3.signal();
 93          finally 
 94             lock.unlock();
 95         
 96     
 97     public void loopC(int totaloop) 
 98         lock.lock();
 99         
100         try 
101             //判断
102             if(flag != 3) 
103                 try 
104                     condition3.await();
105                  catch (InterruptedException e) 
106                 
107             
108             //打印
109             for (int i = 1; i <= 1; i++) 
110                 System.out.println(Thread.currentThread().getName() +"\t"+ i+ "\t" + totaloop);
111             
112             //唤醒
113             flag = 1 ;
114             condition1.signal();
115          finally 
116             lock.unlock();
117         
118     
119     
120     
121