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();
        }
    }
    
}