使用java多线程实现火车站售票的问题

package com.softeem.demo;

/**
*@author leno
*售票类
*/
class SaleTicket implements Runnable {
    int tickets = 100;

    public void run() {
      while (tickets > 0) {
          sale();
//或者下面这样实现
//        synchronized (this) {
//            if (tickets > 0) {
//                System.out.println(Thread.currentThread().getName() + "卖第"
//                      + (100 - tickets + 1) + "张票");
//                tickets--;
//            }
//        }
      }
    }

    public synchronized void sale() {
      if (tickets > 0) {
          System.out.println(Thread.currentThread().getName() + "卖第"
                  + (100 - tickets + 1) + "张票"); //打印第几个线程正在执行
          tickets--;
      }
    }

}

public class TestSaleTicket {

    public static void main(String[] args) {
      SaleTicket st = new SaleTicket();
      new Thread(st, "一号窗口").start();
      new Thread(st, "二号窗口").start();
      new Thread(st, "三号窗口").start();
      new Thread(st, "四号窗口").start();

    }
}