我是Java双非初学者，这道实验题运行不出来

代码如下:class Student {
public int studentid;
public String name;
public int birthday;
public String department;
public String girlfriend;

public void getInfo() {
    System.out.println("studentid+name+birthday+department+girlfriend");
}

}

class Undergraduate extends Student {
    public String counsler;

    public void getInfo() {
        System.out.println("counsler");
    }
}

class Graduate extends Student {
    public String supervisor;

    public void getInfo() {
        System.out.println("supervisor");
    }
}

class test {

    void main() {

        {
            Undergraduate Zhong = new Undergraduate();
            Zhong.name = "小明";
            Zhong.birthday = 2002201;
            Zhong.studentid = 55;
            Zhong.department = "信息学院";
            Zhong.girlfriend = "小红";
            Zhong.counsler = "琳琳";
            Zhong.getInfo();
        }
    }
}

题目和运行结果在这

我调到心灰意冷了😭

public class Student {
    public int studentid;
    public String name;
    public int birthday;
    public String department;
    public String girlfriend;

    public void getInfo() {
        System.out.println(studentid+name+birthday+department+girlfriend);
    }

}

public class Undergraduate extends Student {
    public String counsler;

    @Override
    public void getInfo() {
        System.out.println(studentid+name+birthday+department+girlfriend+counsler);
    }

}

public class Graduate extends Student {
    public String supervisor;

    @Override
    public void getInfo() {
        System.out.println(studentid+name+birthday+department+girlfriend+supervisor);
    }

}
class test {

    public static void main(String[] args) {
        Undergraduate Zhong = new Undergraduate();
        Zhong.name = "小明";
        Zhong.birthday = 2002201;
        Zhong.studentid = 55;
        Zhong.department = "信息学院";
        Zhong.girlfriend = "小红";
        Zhong.counsler = "琳琳";
        Zhong.getInfo();
        Graduate Zhong1 = new Graduate();
        Zhong1.name = "小明";
        Zhong1.birthday = 2002201;
        Zhong1.studentid = 55;
        Zhong1.department = "信息学院";
        Zhong1.girlfriend = "小红";
        Zhong1.supervisor = "计科系";
        Zhong1.getInfo();

    }
    }

改成这样试试

public static void main(String args[]) {
 
        {
            Undergraduate Zhong = new Undergraduate();
            Zhong.name = "小明";
            Zhong.birthday = 2002201;
            Zhong.studentid = 55;
            Zhong.department = "信息学院";
            Zhong.girlfriend = "小红";
            Zhong.counsler = "琳琳";
            Zhong.getInfo();
        }
    }

你真是个人才

class Student {
    public int studentid;
    public String name;
    public int birthday;
    public String department;

    public void getInfo() {
        System.out.println("学号：" + studentid + "，姓名：" + name + "，出生日期：" + birthday + "，所属院系：" + department);
    }
}

class Undergraduate extends Student {
    public String counselor;

    public void getInfo() {
        System.out.println("学号：" + studentid + "，姓名：" + name + "，出生日期：" + birthday + "，所属院系：" + department + "，辅导员：" + counselor);
    }
}

class Graduate extends Student {
    public String supervisor;

    public void getInfo() {
        System.out.println("学号：" + studentid + "，姓名：" + name + "，出生日期：" + birthday + "，所属院系：" + department + "，导师：" + supervisor);
    }
}

public class test {

    public static void main(String[] args) {
            Undergraduate Zhong = new Undergraduate();
            Zhong.name = "小明";
            Zhong.birthday = 2002201;
            Zhong.studentid = 55;
            Zhong.department = "信息学院";
            Zhong.counselor = "琳琳";
            Zhong.getInfo();
            Graduate g = new Graduate();
            g.name = "张三";
            g.birthday = 20000401;
            g.studentid = 38;
            g.department = "信息学院";
            g.supervisor = "李四";
            g.getInfo();
        }
}