补以下 代码class Student extends Person{

public class Demo {
public static void main(String[] args) {
Person p = new Person( "小明", 12) ;
Student s = new Student ("小红", 18, 78.5) ;
}
}
class Person{
String name;
int age;
public Person(String name, int age) {
this.name= name;
this.age =age;
补代码

再加个子类就好了，希望采纳谢谢

class Student extends Person {
      double  weight;
      public Student(String name,int age,double weight){
             super(name,age);
             this.weight = weight;
      }
}

假设Student类是Person类的子类，

class Student extends Person {
    double score;
    public Student(String name, int age, double score) {
        super(name, age);
        this.score = score;
    }
}

完整代码：

```java
public class Demo {
    public static void main(String[] args) {
        Person p = new Person("小明", 12);
        Student s = new Student("小红", 18, 78.5);
    }
}

class Person {
    String name;
    int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

class Student extends Person {
    double score;

    public Student(String name, int age, double score) {
        super(name, age);
        this.score = score;
    }
}

```