CAS

https://www.jianshu.com/p/8de8c6a839e8

public class Automic1 {
    //AtomicInteger解决不了ABA问题，ABA问题可能在业务场景下会导致问题，例如一个人去取款，取款机因为特殊原因启动了两个线程，其中一个线程执行扣减成功，本来100块钱，结果取了50，账户应该剩余50块钱
    //线程2因为阻塞未扣减，此时若不存在线程三，则会扣减失败，但是若此时线程三是加上50块钱，线程三执行完成之后，线程2才去执行，此时线程2以为并未扣减，然后扣减，导致账户最终只有50块钱
    static AtomicInteger automic = new AtomicInteger(10);
    //可使用AtomicStampedReference来解决ABA问题，因为此加上了版本控制，每更新一次，会收到改变stamp的值7
   static AtomicStampedReference atomicStampedRef=new AtomicStampedReference(10,0);//加上了版本号控制，解决了ABA问题
    public static void main(String[] args) throws InterruptedException {
        Thread t1=new Thread(()->{
            automic.compareAndSet(10,11);
            automic.compareAndSet(11,10);
        });
        Thread t2=new Thread(()->{
            boolean c3=automic.compareAndSet(10,11);
            System.out.println(c3+""+automic.get());
        });

        t1.start();
        t2.start();
        t1.join();
        t2.join();
        Thread refT1 = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                }
                atomicStampedRef.compareAndSet(100, 101, atomicStampedRef.getStamp(), atomicStampedRef.getStamp() + 1);
                atomicStampedRef.compareAndSet(101, 100, atomicStampedRef.getStamp(), atomicStampedRef.getStamp() + 1);
            }});

    Thread refT2 = new Thread(new Runnable() {
        @Override
        public void run() {
            int stamp = atomicStampedRef.getStamp();
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
            }
            boolean c3 = atomicStampedRef.compareAndSet(100, 101, stamp, stamp + 1);
            System.out.println(c3); // false
        }
    });
        refT1.start();
        refT2.start();
    }