作用

通过版本号解决ABA的问题。

示例

public class AtomicStampedReferenceDemo {    static AtomicStampedReference<Integer> stampedReference = new AtomicStampedReference<>(1, 1);    public static void main(String[] args) throws InterruptedException {        int oldStamp = stampedReference.getStamp();        Thread thread1 = new Thread(new Runnable() {            @Override            public void run() {                boolean result = stampedReference.compareAndSet(1, 2, oldStamp, oldStamp + 1);                System.out.println("当前值：1，预设2,当前版本号：" + stampedReference.getStamp() + ",结果：" + result);            }        });        Thread thread2 = new Thread(new Runnable() {            @Override            public void run() {                try {                    Thread.sleep(1000);                } catch (InterruptedException e) {                    e.printStackTrace();                }                boolean result = stampedReference.compareAndSet(2, 3, oldStamp, oldStamp + 1);                System.out.println("当前值：2，预设3,当前版本号：" + stampedReference.getStamp() + ",结果：" + result);            }        });        thread1.start();        thread2.start();        Thread.sleep(2000);        System.out.println("当前值：" + stampedReference.getReference() + ",当前版本号：" + stampedReference.getStamp());    }}

运行结果如下：

这里用休眠，让线程1和线程2一次执行，通过结果可以看出来，线程1执行成功，而线程2执行失败。原因就是因为版本号对不上。