求大神帮我看看这程序哪里有问题 运行的时候有时候会出现相同的票数

package com.homework;
public class BuyTickets1 implements Runnable {
static int tickets = 30;
private String name;

public BuyTickets1(String name) {
    this.name = name;
}

public void run() {
    for (int i = 1; i <= 35; i++) {
        synchronized (this) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            tickets--;
            if (tickets > 0) {
                System.out.println("窗口" + name + "卖了一张票" + "还剩" + tickets
                        + "张票");
            } else if (tickets == 0) {
                System.out.println("票已售完");
            }
        }
    }
}

public static void main(String[] args) {
    new Thread(new BuyTickets1("A")).start();
    new Thread(new BuyTickets1("B")).start();
    new Thread(new BuyTickets1("C")).start();
}

}

相同的票数指的哪里相同啊？ 是三个窗口卖的票数相同还是剩余的票数相同啊？

synchronized线程问题，因为你每次运行并没有去计算剩余票票数，希望对你有用.....