2.2.6验证同步代码块时锁定当前对象的

Posted 2020-10-17 成功的路上总是离不开贵人的帮助，名师的指点和小人的刺激。

和synchronized方法一样，synchronized(this)代码块也是锁定当前对象的。

package com.cky.utils;

/**
 * Created by chenkaiyang on 2017/12/6.
 */
public class Task {

    public  void otherMethod() {
        System.out.println("othermethod start");
    }
    public void serviceMethodA(){
        synchronized (this) {
            for (int i = 0; i < 100; i++) {
                System.out.println("同步"+ Thread.currentThread().getName() +" i="+(i+1));
            }
        }

    }
}

package com.cky.thread;

import com.cky.utils.Task;

/**
 * Created by chenkaiyang on 2017/12/5.
 */
public class ThreadA extends Thread{
    private Task service;
    public ThreadA(Task service) {
        super();
        this.service = service;
    }

    @Override
    public void run() {
        super.run();
        service.serviceMethodA();
    }
}

package com.cky.thread;

import com.cky.utils.Task;

/**
 * Created by chenkaiyang on 2017/12/5.
 */
public class ThreadB extends  Thread{
    private Task service;
    public ThreadB(Task service) {
        super();
        this.service = service;
    }

    @Override
    public void run() {
        super.run();
        service.otherMethod();
    }
}

package com.cky.test;

import com.cky.thread.ThreadA;
import com.cky.thread.ThreadB;
import com.cky.utils.Task;

/**
 * Created by chenkaiyang on 2017/12/6.
 */
public class Test2 {
    public static void main(String[] args) throws InterruptedException {
        Task task = new Task();
        ThreadA threadA = new ThreadA(task);
        threadA.start();
        ThreadB threadB = new ThreadB(task);
        threadB.start();

    }
}

同步Thread-0 i=5
同步Thread-0 i=6
同步Thread-0 i=7
同步Thread-0 i=8
othermethod start
同步Thread-0 i=9
同步Thread-0 i=10

上面结果执行是异步执行的，下面更改othermethod

package com.cky.utils;

/**
 * Created by chenkaiyang on 2017/12/6.
 */
public class Task {

    synchronized public  void otherMethod() {
        System.out.println("othermethod start");
    }
    public void serviceMethodA(){
        synchronized (this) {
            for (int i = 0; i < 100; i++) {
                System.out.println("同步"+ Thread.currentThread().getName() +" i="+(i+1));
            }
        }

    }
}

同步Thread-0 i=94
同步Thread-0 i=95
同步Thread-0 i=96
同步Thread-0 i=97
同步Thread-0 i=98
同步Thread-0 i=99
同步Thread-0 i=100
othermethod start