关于Java多线程运行机制。为什么循环3次“上课！”会被学生线程同时进行？如何才能实现老师线程的3句“上课！”打印完毕，再打印关于学生的语句呢？

package 10weeks

import java.util.concurrent.TimeUnit;

public class ClassRoom implements Runnable {
    Thread student,teacher;
    ClassRoom(){
        student=new Thread(this);
        student.setName("东东");
        teacher=new Thread(this);
        teacher.setName("王教授");


    }
    public void run(){

        if(Thread.currentThread()==student){
            Stu();
        }
        else if(Thread.currentThread()==teacher){
            Tea();
          }
    }
    public  void Stu() {
            try{
                System.out.println(student.getName()+"正在睡觉，不听课");
                TimeUnit.HOURS.sleep(1);
            } catch (InterruptedException e) {
                System.out.println(student.getName()+"被老师叫醒");
            }
            System.out.println(student.getName()+"开始听课");
            System.out.println(student.getName()+"又开始睡觉");
            try {
                TimeUnit.HOURS.sleep(1);
            } catch (InterruptedException e) {
                System.out.println(student.getName()+"再次被叫醒");
            }
            System.out.println(student.getName()+"被教授罚站！");
            return;
    }
public synchronized void Tea(){
            while (student.isAlive()){
                for (int i=0;i<3;i++){
                    System.out.println("上课！");
                    try {
                       Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                student.interrupt();
    }
}

}
public class test13 {
    public static void main(String args[]){
        ClassRoom room=new ClassRoom();
        room.teacher.start();
        room.student.start();

    }
}

https://blog.csdn.net/whj826069748/article/details/80853314