从头认识多线程-2.7 同步是不具备继承性的

这一章节我们来讨论一下同步是不具备继承性的。

1.代码清单

package com.ray.deepintothread.ch02.topic_7;/** * <br> * <br> *  * @author RayLee * */public class SynchronizationDoesNotHaveInheritance {public static void main(String[] args) throws InterruptedException {Sub sub = new Sub();Father father = new Father();ThreadOne threadOne = new ThreadOne(sub);Thread thread = new Thread(threadOne);thread.start();ThreadTwo threadTwo = new ThreadTwo(sub);Thread thread2 = new Thread(threadTwo);thread2.start();}}class ThreadOne implements Runnable {private Father father;public ThreadOne(Father sub) {this.father = sub;}@Overridepublic void run() {father.service();}}class ThreadTwo implements Runnable {private Father father;public ThreadTwo(Father father) {this.father = father;}@Overridepublic void run() {father.service();}}class Father {protected int count = 0;public synchronized void service() {for (int i = 0; i < 5; i++) {System.out.println("Thread name:" + Thread.currentThread().getName() + " count:" + count++);try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}}}}class Sub extends Father {@Overridepublic void service() {for (int i = 0; i < 5; i++) {System.out.println("Thread name:" + Thread.currentThread().getName() + " count:" + count++);try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}}}}

我们看到上面的代码，当我们放到任务里面的是Father时，输出：

Thread name:Thread-0 count:0
Thread name:Thread-0 count:1
Thread name:Thread-0 count:2
Thread name:Thread-0 count:3
Thread name:Thread-0 count:4
Thread name:Thread-1 count:5
Thread name:Thread-1 count:6
Thread name:Thread-1 count:7
Thread name:Thread-1 count:8
Thread name:Thread-1 count:9

我们看到上面的代码，当我们放到任务里面的是Sub时，输出：

Thread name:Thread-0 count:0
Thread name:Thread-1 count:1
Thread name:Thread-0 count:2
Thread name:Thread-1 count:2
Thread name:Thread-1 count:3
Thread name:Thread-0 count:3
Thread name:Thread-0 count:4
Thread name:Thread-1 count:4
Thread name:Thread-1 count:6
Thread name:Thread-0 count:5

2.对比

我们对比上面的两组输出，很明显的是，第二组输出不具备同步性质，因此，我们可以得出结论，当子类重写父类方法的时候，如果不加入同步标志，一样不具备同步性。

3.结论：同步是不具备继承性的

总结：这一章节主要讨论了同步是不具备继承性的。

这一章节就到这里，谢谢

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我的github：https://github.com/raylee2015/DeepIntoThread

目录：http://blog.csdn.net/raylee2007/article/details/51204573