129 - Shape类

形状类设计与实现

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129 - Shape类

Time Limit: 1000 Memory Limit: 65535
Submit: 441 Solved: 259

Description

定义一个形状类Shape，提供计算周长getPerimeter()和面积getArea()的函数
定义一个子类正方形类Square继承自Shape类，拥有边长属性，提供构造函数，能够计算周长getPerimeter()和面积getArea()
定义一个子类长方形类Rectangle继承自Square类，拥有长、宽属性，提供构造函数，能够计算周长getPerimeter()和面积getArea()
定义一个子类圆形类Circle继承自Shape，拥有半径属性，提供构造函数，能够计算周长getPerimeter()和面积getArea()

在main函数中，分别构造三个子类的对象，并输出他们的周长、面积.

Input

正方形类的边长
长方形类的长宽
圆类的半径

Output

正方形的周长、面积
长方形的周长、面积
圆形的周长、面积

Sample Input

1
1 2
2

Sample Output

4.00 1.00
6.00 2.00
12.57 12.57

HINT

用System.out.printf("%.2f",d)进行格式化输出

Pre Append Code

import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
         Scanner scan = new Scanner(System.in);      
         double length = scan.nextDouble();
         Square s = new Square(length);
         System.out.printf("%.2f ",s.getPerimeter());
         System.out.printf("%.2f\n",s.getArea());

         length = scan.nextDouble();
         double wide = scan.nextDouble();
         Rectangle r = new Rectangle(length,wide);
         System.out.printf("%.2f ",r.getPerimeter());
         System.out.printf("%.2f\n",r.getArea());

         double radius = scan.nextDouble();
         Circle c = new Circle(radius);
         System.out.printf("%.2f ",c.getPerimeter());
         System.out.printf("%.2f\n",c.getArea());

         scan.close(); 
    }
}

abstract class Shape
{
	public abstract double getPerimeter();
	public abstract double getArea();
}
class Square extends Shape
{
	double length;
	public Square(double length)
	{
		this.length = length;
	}
	@Override
	public double getPerimeter()
	{
		return 4 * length;
	}
	@Override
	public double getArea()
	{
		return length * length;
	}
}
class Rectangle extends Square
{
	double width;
	public Rectangle(double length,double width)
	{
		super(length);
		this.width = width;
	}
	@Override
    public double getArea() {
        return length*width;
    }

    @Override
    public double getPerimeter() {
        return 2*(length+width);
    }
}
class Circle extends Shape
{
	double r;
	public Circle(double r)
	{
		this.r = r;
	}
	@Override
	public double getArea() 
	{
        return Math.PI * r * r;
    }
    @Override
    public double getPerimeter() 
    {
        return 2 * Math.PI * r;
    }
}