程序纠错

因为你这两个线程没有公用同一个saleTicket对象对你程序修改如下：

public class maipiao implements Runnable {

    Thread wang, li;

    saleTicket saleTicket=new saleTicket();

    maipiao() {
        wang = new Thread(this);
        li = new Thread(this);
    }

    @Override
    public void run() {
        if (Thread.currentThread() == wang) {
            saleTicket.rule(5);
        } else if (Thread.currentThread() == li) {
            saleTicket.rule(20);
        }

    }

    public static void main(String[] args) {
        maipiao a = new maipiao();
        a.wang.start();
        a.li.start();
    }
}

class saleTicket {
    int ticket5 = 2, ticket10 = 0, ticket20 = 0;

    public synchronized void rule(int money) {

        System.out.println("money:"+money+"|"+ticket5);
        if (money == 5) {
            ticket5 = ticket5 + 1;
            System.out.println("给你票，你的钱正好");
        } else if (money == 20) {
            while (ticket5 < 3) {
                try {
                    wait();
                } catch (InterruptedException e) {
                }
            }
            ticket20 = ticket20 + 1;
            ticket5 = ticket5 - 3;
            System.out.println("给你票，你给我20，找你15元");
        }
        notifyAll();
    }
}