java多线程笔记--Atomic原子操作类

Posted 2022-12-05 SingleOneMan

java多线程笔记–Atomic原子操作类

文章目录

• java多线程笔记--Atomic原子操作类
• • • 1Atomic原子操作多线程计数
    • 2.synchronized多线程计数

1Atomic原子操作多线程计数

**
 * @Description:
 * Atomic原子操作类，用法简单，线程安全的更新变量
 * @Author:
 * @Date: 2019/5/14 23:56
 */
public class TestAtomicCount 
    private  static  AtomicInteger num = new AtomicInteger(0);
    public static void main(String[] args) throws InterruptedException
        for(int k=0;k<100;k++)
            CountDownLatch countDownLatch = new CountDownLatch(3);
            num.set(0);
            Thread t1 =new Thread(new CountRunnable(countDownLatch));
            Thread t2 =new Thread(new CountRunnable(countDownLatch));
            Thread t3 =new Thread(new CountRunnable(countDownLatch));
            t1.start();
            t2.start();
            t3.start();
            countDownLatch.await();
            System.out.println("第"+(k+1)+"次计算结果，num=" + num.get());
        
    
    public static  class CountRunnable implements Runnable
        private CountDownLatch countDownLatch;
        CountRunnable (CountDownLatch countDownLatch)
            this.countDownLatch=countDownLatch;
        
        @Override
        public void run() 
            for (int i=0;i<10000;i++)
                num.incrementAndGet();
                // System.out.println(Thread.currentThread().getName()+":"+num);
            
            countDownLatch.countDown();
        
    

2.synchronized多线程计数

**
 * @Description:
 * synchronized 来解决多线程更新变量的问题
 * @Author:
 * @Date: 2019/5/14 23:49
 */
public class TestThreadCount 
    private  static  int num =0;
    public static void main(String[] args)throws InterruptedException 
        for(int k=0;k<100;k++)
            CountDownLatch countDownLatch = new CountDownLatch(3);
            num=0;
            Thread t1 =new Thread(new CountRunnable(countDownLatch));
            Thread t2 =new Thread(new CountRunnable(countDownLatch));
            Thread t3 =new Thread(new CountRunnable(countDownLatch));
            t1.start();
            t2.start();
            t3.start();
            countDownLatch.await();
            System.out.println("第"+(k+1)+"次计算结果，num=" + num);
        
    

    public static  class CountRunnable implements Runnable
        private CountDownLatch countDownLatch;
        CountRunnable (CountDownLatch countDownLatch)
            this.countDownLatch=countDownLatch;
        
        @Override
        public void run() 
            //synchronized(this)代表锁住同一对象。
            //synchronized(CountRunnable.class)代表锁住整个CountRunnable类的对象。
            synchronized (CountRunnable.class)
                for (int i=0;i<10000;i++)
                    num=num+1;
                   // System.out.println(Thread.currentThread().getName()+":"+num);
                
            
            countDownLatch.countDown();