package com.ljn.base;

/**

 * @author lijinnan

 * @date:2013-9-12 上午9:55:32

 */

public class IncDecThread2 {

    /**

     * 测试次数

     */

    public static final int TEST_COUNT = 20;

    /*

     * 题目:用JAVA写一个多线程程序，写四个线程，其中二个对一个变量加1，另外二个对一个变量减1

     * 两个问题：

     * 1、线程同步--synchronized

     * 2、线程之间如何共享同一个j变量--将j以及对j的操作封装在Data类中，然后作为共享对象传递给IncRunnable和DecRunnable

     *

     * 相对上面第一种解法（利用内部类），本解法更符合面向对象的思想

     */

    public static void main(String[] args) {

        Data data = new Data();

        //加1线程，2个

        new Thread(new IncRunnable(data)).start();

        new Thread(new IncRunnable(data)).start();

        //减1线程，2个

        new Thread(new DecRunnable(data)).start();

        new Thread(new DecRunnable(data)).start();

    }

}

class Data {

    private int j = 10;

    public synchronized void inc () {

        j++;

        System.out.println(Thread.currentThread().getName()+"-inc:"+j);

    }

    public synchronized void dec () {

        j--;

        System.out.println(Thread.currentThread().getName()+"-dec:"+j);

    }

}

class IncRunnable implements Runnable {

    private Data data;

    public IncRunnable (Data data) {

        this.data = data;

    }

    @Override

    public void run() {

        for (int i = 0; i < IncDecThread2.TEST_COUNT; i++) {

            data.inc();

        }

    }

}

class DecRunnable implements Runnable {

    private Data data;

    public DecRunnable (Data data) {

        this.data = data;

    }

    @Override

    public void run() {

        for (int i = 0; i < IncDecThread2.TEST_COUNT; i++) {

            data.dec();

        }

    }

}