Studnet类

package entity;

public class Student {
    public String name;  //姓名
    public Integer age;  //年龄

    //无参构造函数
    public Student() {}

    //含参构造函数
    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }

    //打印学生信息
    public void Show() {
        System.out.println("姓名："+this.getName()+"  年龄："+this.getAge());
    }
}

Undergrated类

package entity;

public class Undergraduate extends Student {
    public String degree;   //学位

    public Undergraduate(String name,Integer age,String degree) {
        super(name,age);
        this.degree = degree;
    }

    public String getDegree() {
        return degree;
    }

    public void setDegree(String degree) {
        this.degree = degree;
    }

    public void  Show() {
        System.out.println( "姓名："+this.getName()+"  年龄："+this.getAge()+"  学位："+this.getDegree());
    }

}

测试类

import entity.Student;
import entity.Undergraduate;

public class main {

    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        Student student1=new Student("张三",25);
        student1.Show();

        Undergraduate undergraduate1=new Undergraduate("李四", 20, "博士");
        undergraduate1.Show();
    }

}