多线程-并发卖票

package test;

/**
 * author：songyan
 * date: 2019/11/10
 **/
public class demo1 {
    public static void main(String[] args) {
        Tickert t = new Tickert();
        Thread t1 = new Thread(t);
        Thread t2 = new Thread(t);
        Thread t3 = new Thread(t);
        Thread t4 = new Thread(t);

        t1.start();
        t2.start();
        t3.start();
        t4.start();
    }
}

class Tickert implements Runnable {
    private int number = 100;//一共一百张票
    Object obj = new Object();
    @Override
    public void run() {
        while (true) {
            synchronized (obj) {
                if (number > 0) {                   
                    System.out.println("ticket   " + number--);
                }
            }
        }
    }
}

通过加锁防止出现错票