7.2 AtomicReferenct类

1.Atomic下提供了AtomicReferenct类方便来操作对象、数组，如下：
在并发场景下通过atomicReference来操作同一个user对象类了,从而达到原子性，而不是通过user.age进行直接赋值了。

public class AtomicReferenctSample {
    //AtomicReference操作对象
    static User user = new User(18);
    static AtomicReference<User> atomicReference = new AtomicReference<User>(user);
    //AtomicReferenceArray操作数组
    static User[] users = new User[]{new User(20),new User(21)};
    static AtomicReferenceArray<User> atomicReferenceArray = new AtomicReferenceArray(users);
    //AtomicIntegerFieldUpdater修改int
    static AtomicIntegerFieldUpdater atomicIntegerFieldUpdaterAge = AtomicIntegerFieldUpdater.newUpdater(User.class,"ageTmp");
    //AtomicReferenceFieldUpdater修改String
    static AtomicReferenceFieldUpdater atomicReferenceFieldUpdater = AtomicReferenceFieldUpdater.newUpdater(User.class,String.class,"name");
    public static void main(String[] args) {
        //并发场景下就可以通过atomicReference来操作同一个user对象类了,从而达到原子性。
        System.out.println("----------------AtomicReference---------------");
        System.out.println(atomicReference.get().age);
        atomicReference.set(new User(19));
        System.out.println(atomicReference.get().age);
        System.out.println("----------------AtomicReferenceArray---------------");
        System.out.println(atomicReferenceArray.get(0).age);
        atomicReferenceArray.set(0,new User(22));
        System.out.println(atomicReferenceArray.get(0).age);
        System.out.println("----------------AtomicIntegerFieldUpdater---------------");
        atomicIntegerFieldUpdaterAge.getAndIncrement(user);
        System.out.println(atomicIntegerFieldUpdaterAge.get(user));
        atomicIntegerFieldUpdaterAge.getAndSet(user,20);
        System.out.println(atomicIntegerFieldUpdaterAge.get(user));
        System.out.println("----------------AtomicReferenceFieldUpdater---------------");
        atomicReferenceFieldUpdater.getAndSet(user,"test");
        System.out.println(atomicReferenceFieldUpdater.get(user));
    }
    static class User{
        public User(int age){
            this.age = age;
            this.ageTmp = age;
        }
        public int age;
  //注意这里如果是想用Atomic原子包下的对应类进行操作的话,要加volatile可见性和public权限
        public volatile int ageTmp;
        public volatile String name;
    }
}