java volatile 废话不多说，来看代码

最新推荐文章于 2025-01-20 07:30:00 发布

原创最新推荐文章于 2025-01-20 07:30:00 发布 · 置顶 · 244 阅读

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本文通过一个Java多线程示例，深入探讨了Volatile关键字的作用。演示了在使用与未使用Volatile修饰符的情况下，共享变量MY_INT在两个并发线程间的同步效果，揭示了Volatile确保内存可见性和禁止指令重排的重要性。

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public class VolatileTest{

    private static int MY_INT = 0;

    public static void main(String[] args) {
        new ChangeListener().start();
        new ChangeMaker().start();
    }

    static class ChangeListener extends Thread {
        @Override
        public void run() {
            int local_value = MY_INT;
            while ( local_value < 10){
                if( local_value!= MY_INT){
                    System.out.println(String.format("Got Change for MY_INT : [ %s ]",MY_INT));
                    local_value= MY_INT;
                }
            }
        }
    }

    static class ChangeMaker extends Thread{
        @Override
        public void run() {

            int local_value = MY_INT;
            while (MY_INT <10){
                System.out.println(String.format("Got Change for MY_INT : [ %s ]", local_value+1));
                MY_INT = ++local_value;
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) { e.printStackTrace(); }
            }
        }
    }
}

private static int MY_INT = 0; 没有Volatileg关键字修饰输出为 :

Got Change for MY_INT : [ 1 ]
Got Change for MY_INT : [ 2 ]
Got Change for MY_INT : [ 3 ]
Got Change for MY_INT : [ 4 ]
Got Change for MY_INT : [ 5 ]
Got Change for MY_INT : [ 6 ]
Got Change for MY_INT : [ 7 ]
Got Change for MY_INT : [ 8 ]
Got Change for MY_INT : [ 9 ]
Got Change for MY_INT : [ 10 ]

private static volatile int MY_INT = 0; 有Volatile关键字修饰输出为 :

Got Change for MY_INT : [ 1 ]
Got Change for MY_INT : [ 1 ]
Got Change for MY_INT : [ 2 ]
Got Change for MY_INT : [ 2 ]
Got Change for MY_INT : [ 3 ]
Got Change for MY_INT : [ 3 ]
Got Change for MY_INT : [ 4 ]
Got Change for MY_INT : [ 4 ]
Got Change for MY_INT : [ 5 ]
Got Change for MY_INT : [ 5 ]
Got Change for MY_INT : [ 6 ]
Got Change for MY_INT : [ 6 ]
Got Change for MY_INT : [ 7 ]
Got Change for MY_INT : [ 7 ]
Got Change for MY_INT : [ 8 ]
Got Change for MY_INT : [ 8 ]
Got Change for MY_INT : [ 9 ]
Got Change for MY_INT : [ 9 ]
Got Change for MY_INT : [ 10 ]
Got Change for MY_INT : [ 10 ]