java concurrent AtomicReference

java concurrent AtomicReference

AtomicReference role

Has introduced AtomicInteger, AtomicIntegerArray, AtomicReference is for the object.
He and volatile by CAS to ensure the visibility of objects and atomic operations, since it is quoted, it will cause a change in a reference object.

    public AtomicReference(V initialValue) {
        value = initialValue;
    }

If the value has changed the properties of an object, initialValue properties will change
to realize the function of CAS

    /**
     * Atomically sets the value to the given updated value
     * if the current value {@code ==} the expected value.
     * @param expect the expected value
     * @param update the new value
     * @return {@code true} if successful. False return indicates that
     * the actual value was not equal to the expected value.
     */
    public final boolean compareAndSet(V expect, V update) {
        return unsafe.compareAndSwapObject(this, valueOffset, expect, update);
    }

example

package javalearn.javabase.thread.atomic;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.atomic.AtomicReference;

@Slf4j
public class AtomicReferanceTest {
    public static void main(String[] args) {
        Persion p1 = new Persion("jack", 1);
        Persion p2 = new Persion("linda", 2);
        Persion p3 = new Persion("tony", 3);
        log.info("persion 3 :{}",p3.toString());

        AtomicReference<Persion> atomicReference =new AtomicReference(p3);
        log.info("AtomicReference is :{}",atomicReference.toString());
        atomicReference.compareAndSet(p3,p1);
        log.info("AtomicReference is :{}",atomicReference.toString());
        log.info("persion 3 :{}",p3.toString());
        atomicReference.set(p2);
        log.info("AtomicReference is :{}",atomicReference.toString());
        log.info("persion 3 :{}",p3.toString());
        atomicReference.get().setId(33);
        log.info("AtomicReference is :{}",atomicReference.toString());
        log.info("AtomicReference is :{}",atomicReference.toString());
        log.info("persion 3 :{}",p3.toString());
        log.info("persion 2 :{}",p2.toString());

    }

    @AllArgsConstructor
    @Data
    @ToString
    static class Persion {
        private String name;
        private int id;

    }
}

result

13:34:22.313 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - persion 3 :AtomicReferanceTest.Persion(name=tony, id=3)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - AtomicReference is :AtomicReferanceTest.Persion(name=tony, id=3)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - AtomicReference is :AtomicReferanceTest.Persion(name=jack, id=1)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - persion 3 :AtomicReferanceTest.Persion(name=tony, id=3)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - AtomicReference is :AtomicReferanceTest.Persion(name=linda, id=2)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - persion 3 :AtomicReferanceTest.Persion(name=tony, id=3)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - AtomicReference is :AtomicReferanceTest.Persion(name=linda, id=33)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - AtomicReference is :AtomicReferanceTest.Persion(name=linda, id=33)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - persion 3 :AtomicReferanceTest.Persion(name=tony, id=3)
13:34:22.321 [main] INFO javalearn.javabase.thread.atomic.AtomicReferanceTest - persion 2 :AtomicReferanceTest.Persion(name=linda, id=33)