史上最全的Java并发系列之Java中的13个原子操作类

public static void main(String[] args) {
    AtomicInteger ai = new AtomicInteger(1);
    System.out.println("ai.get() = " + ai.get());
    System.out.println("ai.addAndGet(5) = " + ai.addAndGet(5));
    System.out.println("ai.get() = " + ai.get());
    System.out.println("ai.compareAndSet(ai.get(), 10) = " + ai.compareAndSet(ai.get(), 10));
    System.out.println("ai.get() = " + ai.get());
    System.out.println("ai.getAndIncrement() = " + ai.getAndIncrement());
    System.out.println("ai.get() = " + ai.get());
    ai.lazySet(8);
    System.out.println("ai.lazySet(8)");
    System.out.println("ai.get() = " + ai.get());
    System.out.println("ai.getAndSet(5) = " + ai.getAndSet(5));
    System.out.println("ai.get() = " + ai.get());
}
复制代码

ai.get() = 1
ai.addAndGet(5) = 6
ai.get() = 6
ai.compareAndSet(ai.get(), 10) = true
ai.get() = 10
ai.getAndIncrement() = 10
ai.get() = 11
ai.lazySet(8)
ai.get() = 8
ai.getAndSet(5) = 8
ai.get() = 5
复制代码

public final int getAndIncrement() {
    for (; ; ) {
        int current = get();
        int next = current + 1;
        if (compareAndSet(current, next)) {
            return current;
        }
    }
}
public final boolean compareAndSet(int expect, int update) {
    return unsafe.compareAndSwapInt(this, valueOffset, expect, update);
}
复制代码

/**
 * 如果当前数值是expected，则原子的将Java变量更新成x
 *
 * @return 如果更新成功则返回true
 */
public final native boolean compareAndSwapObject(Object o, long offset,
                                                 Object expected, Object x);
public final native boolean compareAndSwapInt(Object o, long offset,
                                              int expected, int x);
public final native boolean compareAndSwapLong(Object o, long offset,
                                               long expected, long x);
复制代码

public static void main(String[] args) {
    int[] value = new int[]{1, 2};
    AtomicIntegerArray ai = new AtomicIntegerArray(value);
    System.out.println("ai.getAndSet(0, 3)");
    ai.getAndSet(0, 3);
    System.out.println("ai.get(0) = " + ai.get(0));
    System.out.println("value[0] = " + value[0]);
    ai.compareAndSet(1, 2, 5);
    System.out.println("ai.compareAndSet(1, 2, 5)");
    System.out.println("ai.get(1) = " + ai.get(1));
}
复制代码

ai.getAndSet(0, 3)
ai.get(0) = 3
value[0] = 1
ai.compareAndSet(1,2,5)
ai.get(1) = 5
复制代码

public class AtomicReferenceTest {
    public static AtomicReference<User> atomicUserRef = new
            AtomicReference<User>();
    public static void main(String[] args) {
        User user = new User("103style", 20);
        atomicUserRef.set(user);
        System.out.println("atomicUserRef.get() = " + atomicUserRef.get().toString());
        User updateUser = new User("xiaoke", 22);
        atomicUserRef.compareAndSet(user, updateUser);
        System.out.println("atomicUserRef.compareAndSet(user, updateUser);");
        System.out.println("atomicUserRef.get() = " + atomicUserRef.get().toString());
    }
    static class User {
        private String name;
        private int age;
        public User(String name, int age) {
            this.name = name;
            this.age = age;
        }
        public String getName() {
            return name;
        }
        public int getAge() {
            return age;
        }
        @Override
        public String toString() {
            return "name='" + name + ", age=" + age;
        }
    }
}
复制代码

atomicUserRef.get() = name='103style, age=20
atomicUserRef.compareAndSet(user, updateUser);
atomicUserRef.get() = name='xiaoke, age=22
复制代码

public class AtomicIntegerFieldUpdaterTest {
    public static void main(String[] args) {
        // 创建原子更新器,并设置需要更新的对象类和对象的属性
        AtomicIntegerFieldUpdater<User> a = AtomicIntegerFieldUpdater.
                newUpdater(User.class, "age");
        // 设置柯南的年龄是10岁
        User conan = new User("conan", 10);
        // 柯南长了一岁,但是仍然会输出旧的年龄
        System.out.println(a.getAndIncrement(conan));
        // 输出柯南现在的年龄
        System.out.println(a.get(conan));
    }
    public static class User {
        public volatile int age;
        private String name;
        public User(String name, int age) {
            this.name = name;
            this.age = age;
        }
        public String getName() {
            return name;
        }
        public int getAge() {
            return age;
        }
    }
}
复制代码

10
11
复制代码