纯作业代码——Java实现接口、继承

//该代码实现结果为如果设定的长和宽相等则实例化正方形（Square）的类，否则实例化矩形类。 interface rect{ public double area(); public void getWidth(double Width); public void getHeight(double Height); } class Rectangle1 implements rect{ double _width,_height; public void getWidth(double Width){ _width=Width; } public void getHeight(double Height){ _height=Height; } public double area(){ return(_width*_height); } } class Square extends Rectangle1{ public double area(){ return(_width*_width); } } public class test1{ //At here ,I use the super class to define rect1. static Rectangle1 rect1; //set the value of width and height,then judge the shape,and Print them public static void SetValue(double width ,double height){ if(width==height) rect1=new Square(); else rect1=new Rectangle1(); rect1.getWidth(width); System.out.println("The Width value is :"+width+"."); rect1.getHeight(height); System.out.println("The Height value is :"+height+"."); if(width==height) System.out.println("The shape is Square!"); else System.out.println("The shape is Rectangle!"); } //get the result,and print it public static void CalcIt(){ System.out.println("The result is :"+rect1.area()+"."); } public static void main(String args[]){ //set the width and height SetValue(10,10); CalcIt(); System.out.println('/n'); //set the width and height SetValue(10,50); CalcIt(); } }

 

这是教材上的一道题。首先写了一个计算矩形的类，然后再让写一个正方形的类来继承矩形类。并且要求重写父类中的至少一个方法。

于是有了这段代码。

 

各位尽管点评。

 

 

 

ps:高等教育出版社的书，“不'错'~~~~(>_<)~~~~ ”