//自旋锁
public class AtomicReferenceThreadDemo {
    static AtomicReference<Thread>atomicReference=new AtomicReference<>();
    static Thread thread;
    public static void lock(){
        thread=Thread.currentThread();
        System.out.println(Thread.currentThread().getName()+"\t"+"coming.....");
        while(!atomicReference.compareAndSet(null,thread)){
        }
    }
    public static void unlock(){
        System.out.println(Thread.currentThread().getName()+"\t"+"over.....");
        atomicReference.compareAndSet(thread,null);
    }
    public static void main(String[] args) {
        new Thread(()->{
            AtomicReferenceThreadDemo.lock();
            try { TimeUnit.SECONDS.sleep(3);  } catch (InterruptedException e) {e.printStackTrace();}
            AtomicReferenceThreadDemo.unlock();
        },"A").start();
        new Thread(()->{
            AtomicReferenceThreadDemo.lock();
            AtomicReferenceThreadDemo.unlock();
        },"B").start();
    }
}