你真的掌握了并发编程volatile synchronized么?

先看代码:importjava.util.concurrent.atomic.AtomicInte
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先看代码:


import java.util.concurrent.atomic.AtomicInteger;

/**
 *
 * @author xialuomantian
 */
public class NewTest {

    static volatile int a = 1;
    static volatile int b = 1;
    //static  int a = 1;
    //static  int b = 1;
    public static AtomicInteger aa = new AtomicInteger(0);
    public static AtomicInteger bb = new AtomicInteger(0);
    public static AtomicInteger ab = new AtomicInteger(0);
    
    static void add() {
        a++;
        b++;
    }

    static synchronized void print() {
        if (a > b) {
            aa.getAndIncrement();           
        } else if (a < b) {
            bb.getAndIncrement();
        } if (a == b) {
            ab.getAndIncrement();
        }
    }

    public static void main(String[] args) {
        System.out.println(Thread.currentThread().getName());
        for (int i = 0; i < 100000; i++) {

            new Thread(() -> {               
                add();
                print();
            }).start();
        }
        System.out.println("a>b:" + aa);
        System.out.println("b>a:" + bb);
        System.out.println("a==b:" + ab);
    }
}

再去掉volatile

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.mycompany.mytest;

import java.util.concurrent.atomic.AtomicInteger;

/**
 *
 * @author xialuomantian
 */
public class NewTest {

    static  int a = 1;
    static  int b = 1;
    public static AtomicInteger aa = new AtomicInteger(0);
    public static AtomicInteger bb = new AtomicInteger(0);
    public static AtomicInteger ab = new AtomicInteger(0);
    
    static void add() {
        a++;
        b++;
    }

    static synchronized void print() {
        if (a > b) {
            aa.getAndIncrement();           
        } else if (a < b) {
            bb.getAndIncrement();
        } if (a == b) {
            ab.getAndIncrement();
        }
    }

    public static void main(String[] args) {
        System.out.println(Thread.currentThread().getName());
        for (int i = 0; i < 100000; i++) {

            new Thread(() -> {               
                add();
                print();
            }).start();
        }
        System.out.println("a>b:" + aa);
        System.out.println("b>a:" + bb);
        System.out.println("a==b:" + ab);
    }
}

下面是几种结果:

本文来源21aspnet,由架构君转载发布,观点不代表Java架构师必看的立场,转载请标明来源出处:https://javajgs.com/archives/2015

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