关于synchronized锁机制的问题

习题：模拟一个人生产50个玩具，每200毫秒生产一个，当生产到第20个时加入每秒吃1个馒头，共吃完3个后接着生产如下错误代码：
public class Practise2 {
    public static void main(String[] args) {
        Person person=new Person();
        ProductJoy productJoy=new ProductJoy("生产玩具线程",person);
        productJoy.start();
        EatBread eatBread=new EatBread("吃馒头的线程",person);
        eatBread.start();    }
}
class Person{
    int toy=0;
    int bread=0;    public int getToy() {
        return toy;
    }    public  void setToy(int toy) {
        this.toy = toy;
    }    public int getBread() {
        return bread;
    }    public  void setBread(int bread) {
        this.bread = bread;
    }
}
class EatBread extends Thread{    Person person;    public EatBread(String name,Person person){
        super(name);
        this.person=person;
    }
    @Override
    public void run() {
        while(true){            synchronized (person){                person.setBread(person.getBread()+1);
                System.out.println(Thread.currentThread().getName()+"总共吃了馒头："+person.getBread()+" 个");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if(person.getBread()%3==0){
                    person.notify();
                    try {
                        person.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }        }
    }
}class ProductJoy extends Thread{
    Person person;    public ProductJoy(String name,Person person){
        super(name);
        this.person=person;
    }    @Override
    public void run() {
        while(true){            synchronized (person){
                person.setToy(person.getToy()+1);
                System.out.println(Thread.currentThread().getName()+"总共生产玩具："+person.getToy()+"  个");
                try {
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if(person.getToy()>=50) return;
                if(person.getToy()%20==0){
                    person.notify();
                    try {
                        person.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}
问题：输出结果没有达到预期情况，明明生产的玩具没有达到20个，怎么吃馒头的线程就能对锁对象进行吃馒头操作了，这时候不应该等生产玩具的线程synchronized代码块执行完或者调用锁对象.wait方法释放锁对象后，吃馒头的线程获取到锁再进行操作吗？？