java中，某线程调用join()方法后，再调用wait()，为什么其他线程没有执行？

Question

java中，某线程调用join()方法后，再调用wait()，为什么其他线程没有执行？

如何在某线程调用join()方法后，让wait()起效果？

题目：模拟3个人排队买票：张某、李某和赵某要买电影票，售票员只有3张5元钱的，电影票5元一张。张某拿一张20元排在李某的前面买票，李某排在赵某的前面拿一张10元的买票，赵某拿一张5元买票。

class Changes {
    int num = 3;

    public synchronized void sell(int money) throws InterruptedException {
        System.out.println("顾客付了" + money + "元。");
        if (money == 5) {
            num++;
            System.out.println("零钱多了1张5元。");
            notify();
        }
        num -= ((money - 5) / 5);
        if (num < 0) {
            num = 0;
            System.out.println("零钱不足，先给下一名顾客售票。");
            wait(); //这里使用wait
        }
        System.out.println("售票成功！5元的零钱还有" + num + "张。");
    }
}

class Consumer extends Thread {
    public int money;
    Changes changes;

    public Consumer(int money, Changes changes) {
        this.money = money;
        this.changes = changes;
    }

    public void run() {
        try {
            changes.sell(money);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class Test {
    public static void main(String[] args) throws InterruptedException {
        Changes changes = new Changes();
        Consumer consumer1 = new Consumer(20, changes);
        Consumer consumer2 = new Consumer(10, changes);
        Consumer consumer3 = new Consumer(5, changes);
        consumer1.start();
        consumer1.join();
        consumer2.start();
        consumer2.join();
        consumer3.start();
    }
}

预期效果是依次运行consumer1、consumer2、consumer3。
结果consumer2调用wait后并没有运行consumer3，我猜原因是consumer2调用了join，consumer3必须等consumer2结束才执行？
如何才能达到预期效果？

Answer 1

调整了下，这个地方是不需要join的，需要一起去竞争，如果你都join有什么必要加锁呢，都不存在竞争；
第二就是零钱不足不需要充值num=0；这里num是共享资源只要保证线程安全就行。你可以看看 有啥不懂问我

class Changes {
    int num = 3;

    public synchronized void sell(int money) throws InterruptedException {
        String name = Thread.currentThread().getName();
        System.out.println("顾客:" + name + "付了" + money + "元。");
        if (money == 5) {
            num++;
            System.out.println("零钱多了1张5元。");
            notify();
        }
        num -= ((money - 5) / 5);
        if (num < 0) {
            System.out.println("零钱不足，先给下一名顾客售票。");
            wait(); //这里使用wait
        }
        System.out.println("售票给顾客：" + name + "成功！5元的零钱还有" + num + "张。");
    }
}

class Consumer extends Thread {
    public int money;
    Changes changes;

    public Consumer(int money, Changes changes) {
        this.money = money;
        this.changes = changes;
    }

    @Override
    public void run() {
        try {
            changes.sell(money);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class Test {
    public static void main(String[] args) throws InterruptedException {
        Changes changes = new Changes();
        Consumer consumer1 = new Consumer(20, changes);
        Consumer consumer2 = new Consumer(10, changes);
        Consumer consumer3 = new Consumer(5, changes);
        consumer1.start();
//        consumer1.join();
        consumer2.start();
//        consumer2.join();
        consumer3.start();
    }
}