内容发布更新时间 : 2024/5/2 12:21:43星期一 下面是文章的全部内容请认真阅读。

class Fiction implements Book{ double price; // 价格 int pages; // 页数

public Fiction(int pages, double price) { this.pages = pages; this.price = price; }

//实现接口方法Info() public void Info() {

System.out.println(\is a fiction, which has \+ pages + \pages,\costs \ } }

//杂志类

class Magazine implements Book { double price; // 价格 int pages; // 页数

String publish_time; // 出版时间 //构造方法

public Magazine(int pages, double price, String publish_time) { this.pages = pages; this.price = price;

this.publish_time = publish_time; }

//实现接口方法Info() public void Info() {

System.out.println(\pages,\costs \+ price + \yuan, and publish once every \+ publish_time + \ } }

//期刊类

class Journal implements Book{ double price; // 价格 int pages; // 页数

String publish_time; // 出版时间

public Journal(int pages, double price, String publish_time) { this.pages = pages; this.price = price;

this.publish_time = publish_time; }

//实现接口方法Info()

public void Info() {

System.out.println(\is a journal, which has \+ pages + \pages,\costs \+ price + \yuan, and publish once every \+ publish_time + \ } }

//课本类

class Textbook implements Book{

String applicable_object; // 适用对象 double price; // 价格 int pages; // 页数

public Textbook(int pages, double price, String applicable_object) { this.pages = pages; this.price = price;

this.applicable_object = applicable_object; }

//实现接口方法Info() public void Info() {

System.out.println(\pages,\applicable_object +\ } }

public class Test {

public static void main(String[] args) { Fiction f = new Fiction(199, 12); f.Info();

Magazine m = new Magazine(3, 30, \ m.Info();

Journal j = new Journal(274, 36, \ j.Info();

Textbook t = new Textbook(187, 10.19, \ t.Info(); } }

3.编写程序实现求三角形、正方形和圆形的面积，要求先设计一个公共的父类，在其中定义求面积的方法，在继承得到各种形状。 解答：

package work08;

//定义一个抽象类

abstract class Shape{

public abstract void area();//定义一个抽象方法 }

//矩形类

class Rectangle extends Shape{ private double height; private double width;

public Rectangle(double height, double width){ this.height = height; this.width = width; }

//重写抽象方法

public void area() {

double s = (height*width);

System.out.println(\所求矩形面积为\ } }

//定义一个圆形类

class Circle extends Shape{ private double r;

public static final double PI = 3.14;

public Circle(double r){ this.r = r; }

//重写抽象方法

public void area() { double s = PI *r*r;

System.out.println(\所求矩形面积为\ } }

//定义一个三角形类

class Triangle extends Shape{ public double a; public double b; public double c;

public Triangle(double a, double b, double c){ this.a = a; this.b = b; this.c = c; }

//重写抽象方法

public void area() { double q = (a+b+c)/2;

double result = q*(q-a)*(q-b)*(q-c); double s = Math.sqrt(result);

System.out.println(\所求矩形面积为\ } }

public class ShapeDemo {

public static void main (String [] args){ Shape rectangle = new Rectangle(8.0, 7.0); Shape circle = new Circle(1.0);

Shape triangle = new Triangle(3.0, 4.0, 5.0); rectangle.area(); circle.area(); triangle.area(); } }