JAVA多线程售票问题

//定义一个类实现Runnable接口，定义一个需要同步的售票方法，然后重写run方法调用售票的sale方法

class SaleTicket implements Runnable{  
    private int tickets = 100;  
      
      
    private synchronized void sale(){  
        if(tickets > 0){  
            System.out.println(Thread.currentThread().getName() + "卖出 第 "+ (tickets--)+"张票");  
              
            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, "一号窗口");  
        Thread t2 = new Thread(st, "二号窗口");  
        Thread t3 = new Thread(st, "三号窗口");  
        Thread t4 = new Thread(st,"四号窗口 ");  
        t1.start();  
        t2.start();  
        t3.start();  
        t4.start();  
          
      
          
    }  
}
class SaleTicket implements Runnable{
    private int tickets = 100;


    private synchronized void sale(){
        if(tickets > 0){
            System.out.println(Thread.currentThread().getName() + "卖出 第 "+ (tickets--)+"张票");

            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, "一号窗口");
        Thread t2 = new Thread(st, "二号窗口");
        Thread t3 = new Thread(st, "三号窗口");
        Thread t4 = new Thread(st,"四号窗口 ");
        t1.start();
        t2.start();
        t3.start();
        t4.start();



    }
}