同步块demo-03-03

同步块

package cn.ljz.cn.ljz.terminalThread;


/**
 * Created by LIN on 2019/3/3.
 */
public class BuyTicketTest {
    public static void main(String[] args) {
        Syn12306Web web = new Syn12306Web(10);
        new Thread(web, "lin").start();
        new Thread(web, "Mary").start();
        new Thread(web, "Sofia").start();
    }
}

class Syn12306Web implements Runnable {
    int ticketNum;
    boolean flag = true;

    Syn12306Web(int ticketNum) {
        this.ticketNum = ticketNum;
    }
    
    //数据安全：考虑数据完整性，不是代码完整性
    public void test() {
        //考虑没票的情况（个人认为：可能被优化到，但是也可能没有被优化到）
        if (ticketNum <= 0) {
            flag = false;
            return;
        }
        //考虑正常情况和最后一张票的情况
        synchronized (this) {
            if (ticketNum <= 0) {
                flag = false;
                return;
            }
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(Thread.currentThread().getName() + "-->" + ticketNum--);
        }
    }

    @Override
    public void run() {
        while (flag) {
            test();
        }
    }
}