JAVA多線程售票問題

//定義一個類實現Runnable介面，定義一個需要同步的售票方法，然後重寫run方法調用售票的sale方法

class SaleTicket implements Runnable{private int tickets = 100;private synchronized void sale(){if(tickets > 0){System.out.println(Thread.currentThread().getName() + "賣出 第 "+ (tickets--)+"張票");try{Thread.sleep(100);}catch(InterruptedException e){e.printStackTrace();}}}public void run(){while(tickets > 0){sale();}}}public class JavaTest {public static void main(String[] args){SaleTicket st = new SaleTicket();Thread t1 = new Thread(st, "一號視窗");Thread t2 = new Thread(st, "二號視窗");Thread t3 = new Thread(st, "三號視窗");Thread t4 = new Thread(st,"四號視窗 ");t1.start();t2.start();t3.start();t4.start();}}