1903021109—方迪琦—Java第十一周作业—继承多态和抽象类
项目 | 内容 |
班级博客链接 | 19级信计班(本) |
作业要求链接 | 第十一周作业 |
博客名称 | 1903021109—方迪琦—Java第十一周作业—继承多态和抽象类 |
要求 | 每道题要有题目,代码(使用插入代码,不会插入代码的自己查资料解决,不要直接截图代码!!),截图(只截运行结果)。 |
题目1:
- 类Person定义了姓名name,出生年份birthYear,其子类Graduate在继承父类的基础上新增定义了成绩gpa、毕业年份graduateYear。编写测试类,输出毕业生的姓名、年龄、毕业年份、成绩。
- 提示:父类要有构造方法,子类通过super调用父类构造方法。
代码:
父类:
package edu.xj.ff.week11;
public class Person {
private String name;
private int birthYear;
public Person(String name, int birthYear) {
this.name = name;
this.birthYear = birthYear;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getBirthYear() {
return birthYear;
}
public void setBirthYear(int birthYear) {
this.birthYear = birthYear;
}
}
子类:
package edu.xj.ff.week11;
public class Graduate extends Person {
private double gpa;
private int graduateYear;
public Graduate(String name, int birthYear, double gpa, int graduateYear) {
super(name, birthYear);
this.gpa = gpa;
this.graduateYear = graduateYear;
}
public double getGpa() {
return gpa;
}
public void setGpa(double gpa) {
this.gpa = gpa;
}
public int getGraduateYear() {
return graduateYear;
}
public void setGraduateYear(int graduateYear) {
this.graduateYear = graduateYear;
}
}
测试类:
package edu.xj.ff.week11;
public class PersonTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
Graduate G = new Graduate("李华",2000,86,2022);
System.out.println("姓名:"+G.getName()+"\n年龄:"+(G.getGraduateYear()-G.getBirthYear())+"\n毕业年份:"+G.getGraduateYear()+"\n成绩:"+G.getGpa());
}
}
运行结果:
题目2:
- 定义一个基本类Shape,有一个draw方法,定义三个类Circle(圆)、Triangle(三角形)、Square(正方形)都继承于Shape。在测试类中定义一个方法doStuff,传入基本类shape为参数,并调用draw方法。使用父类Shape创建三个类Circle、 Triangle、Square的实例对象并分别作为参数传入draw方法中。
- 提示:多态
代码:
父类:
package edu.xj.ff.week11;
public class Shape {
void draw(){
}
}
子类Circle(圆):
package edu.xj.ff.week11;
public class Circle extends Shape {
void draw(){
System.out.println("Circle.draw()");
}
}
子类Triangln(三角形):
package edu.xj.ff.week11;
public class Triangln extends Shape {
void draw(){
System.out.println("Triangle.draw()");
}
}
子类Square(正方形):
package edu.xj.ff.week11;
public class Square extends Shape {
void draw(){
System.out.println("Square.draw()");
}
}
测试类:
package edu.xj.ff.week11;
public class ShapeTest {
static void doStuff(Shape s){
s.draw();
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Shape c = new Circle();
Shape s = new Square();
Shape t = new Triangln();
doStuff(c);
doStuff(t);
doStuff(s);
}
}
运行结果:
题目3:
-
所有的动物都有一个父类Animal,再定义两个子类Bird(鸟)和Dog(狗)继承自Animal,并实现父类中的bark(叫唤)方法。
- 提示:抽象
代码:
父类:
package edu.xj.ff.week11;
public abstract class Animal {
public void bark(){
}
}
子类Bird(鸟):
package edu.xj.ff.week11;
public class Bird extends Animal {
public void bark(){
System.out.println("鸟叫声是:叽叽喳喳");
}
}
子类Dog(狗):
package edu.xj.ff.week11;
public class Dog extends Animal {
public void bark(){
System.out.println("狗叫声是:汪汪汪");
}
}
测试类:
package edu.xj.ff.week11;
public class AnimalTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
Bird B = new Bird();
Dog D = new Dog();
B.bark();
D.bark();
}
}
运行结果:
题目4:
-
不同几何图形的面积计算公式是不一样的,可是,它们具有的特性是一样的,都具有长和宽这两个属性,也都具有面积计算的方法。根据抽象的概念计算长方形的面积和三角形的面积。
- 提示:抽象
代码:
父类:
package edu.xj.ff.week11;
public abstract class Shape1 {
abstract void Area();
}
子类Rectangle(长方形):
package edu.xj.ff.week11;
public class Rectangle extends Shape1 {
int lenght;
int height;
public Rectangle(int lenght, int height) {
super();
this.lenght = lenght;
this.height = height;
}
void Area() {
// TODO Auto-generated method stub
System.out.println("长方形的面积是:"+lenght*height);
}
}
子类Triangle(三角形):
package edu.xj.ff.week11;
public class Triangle extends Shape1 {
int lenght;
int height;
public Triangle(int lenght, int height) {
super();
this.lenght = lenght;
this.height = height;
}
void Area() {
// TODO Auto-generated method stub
System.out.println("三角形的面积是:"+lenght*height/2);
}
}
测试类:
package edu.xj.ff.week11;
public class Shape1Test {
public static void main(String[] args) {
// TODO Auto-generated method stub
Rectangle R = new Rectangle(5,8);
R.Area();
Triangle T = new Triangle(5,8);
T.Area();
}
}
运行结果:
阅读心得:
1、了解了java中的每一个类都有一个父类,有的显性的表示,有的则隐性表示,但都是继承一Objec,他是所有java类的父类。
2、对多态的概念有了更深入的理解。
3、知道了不是所有的类型都可以相互转换的,只有继承关系的对象之间才可以相互转换。
4、对抽象类的具体用法有了一定的了解。