public class Ticket {private int number =30;public  void sale(){if(number > 0){System.out.println(Thread.currentThread().getName() + "卖出了" +(number--) + "票，剩余：" + number);}}public static void main(String[] args) {Ticket ticket =  new Ticket();new Thread(()->{for (int i = 0; i < 40; i++) {ticket.sale();}},"A").start();new Thread(()->{for (int i = 0; i < 40; i++) {ticket.sale();}},"B").start();new Thread(()->{for (int i = 0; i < 40; i++) {ticket.sale();}},"C").start();}
}

 

 

执行结果：

可以看出多线程情况下，数据是不正确的

 

 

 

传统做法

加上synchronized关键字

加上synchronized关键字看下执行结果，可以看到是有序的