java多线程笔记--Atomic原子操作类

àì夳堔傛蜴生んèń 2022-01-29 04:41 296阅读 0赞

# 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();
            }
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70]

### 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();
            }
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70]: /images/20220129/369696aaea2f4c2091997cb965310027.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 1]: /images/20220129/3cbdff97fc0b45f8906e98d5f155de28.png