从头认识多线程-2.6 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;
	}

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

class ThreadTwo implements Runnable {

	private Father father;

	public ThreadTwo(Father father) {
		this.father = father;
	}

	@Override
	public 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 {
	@Override
	public 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