/* * 模拟 CAS 算法 */
public class TestCompareAndSwap {
    public static void main(String[] args) {
        final CompareAndSwap cas = new CompareAndSwap();

        for (int i = 0; i < 10; i++) {
            new Thread(()->{
                int expectedValue = cas.get();
                boolean boo = cas.compareAndSet(expectedValue, (int)(Math.random() * 100));
                System.out.println(boo+":预估值--"+expectedValue);
            }).start();
        }
    }
}

class CompareAndSwap{
    //模拟内存值
    private int value;

    //获取内存值
    public synchronized int get(){
        return this.value;
    }

    //比较和交换
    public synchronized int compareAndSwap(int expectedValue,int newValue){
        //获取内存值
        int oldValue = value;
        //内存值等于预估值
        if(expectedValue == oldValue){
            //更新内存值
            value = newValue;
        }
        return oldValue;
    }

    //判断是否修改成功
    public synchronized boolean compareAndSet(int expectedValue,int newValue){
        return expectedValue == compareAndSwap(expectedValue, newValue);
    }
}