Question

java 关于子类怎么添加自己新的属性？

abstract class Person {
String name;
int age;
String professional;

Person(String name,int age,String professional) {
this.name= name;
this.age = age;
this.professional=professional;
}
public abstract void display();

}

class Students extends Person {
Students(String n,int a,String p) {
super(n,a,p);
}

public void display() {
System.out.println("我的姓名="+ name + " " + "我的年龄="+age +" " +"我的专业="+professional);
}
}

public class Test5 {
public static void main(String[] args) {
Person p = new Students("男",19,"美术");
Person o = new Students("女",14,"跳舞");
p.display();
o.display();
}
}

这个是我自己写的程序，如果我要在子类里添加多一个新的属性“出生的年份”,并在main里执行。
person p1 = new Students（里面比上面多了个出生的年份)

应该怎么写？

Answer 1

abstract class Person {
String name;
int age;
String professional;

Person(String name,int age,String professional) {
this.name= name;
this.age = age;
this.professional=professional;
}
public abstract void display();

}

class Students extends Person {
int year;
Students(String n,int a,String p,int year) {
super(n,a,p);
this.year=year;
}

public void display() {
System.out.println("我的姓名="+ name + " " + "我的年龄="+age +" " +"我的专业="+professional+"我的出生年为"+year);
}
}

public class Test5 {
public static void main(String[] args) {
Person p = new Students("男",19,"美术");
Person o = new Students("女",14,"跳舞");
p.display();
o.display();
}
}

Answer 2

你可在Students里添加出生年月属性date，然后增加一个构造方法
Students(String n,int a,String p,Date date) {
super(n,a,p);
date = this.date;
}

Answer 3

子类可以有自己特有的属性，直接在子类里面写就可以了