编写一个多线程的程序一个线程输出20次你的学号，另一个输出20次你的姓名Java代码

public class MultiThreadDemo {
    public static void main(String[] args) {
        Thread t1 = new Thread(new StudentIdThread());
        Thread t2 = new Thread(new StudentNameThread());
        t1.start();
        t2.start();
    }
}

class StudentIdThread implements Runnable {
    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            System.out.println("My student id is 2021000000000X.");
        }
    }
}

class StudentNameThread implements Runnable {
    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            System.out.println("My name is John Smith.");
        }
    }
}