Square,Circle继承Shape类，Rectangle继Square

[java]代码库

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(); 
	}        
} 
class Shape{
	private double length;
	private double wide;
	public Shape(double len) {
		length = len;
	}
	public Shape(double len, double wi) {
		length = len;
		wide = wi;
	}
	public double getLength() {
		return length;
	}
	public double getWide() {
		return wide;
	}
	public double getPerimeter() {
		return 2*(length + wide);
	}
	public double getArea() {
		return length*wide;
	}
}

class Square extends Shape{
	public Square(double len){
		super(len, len);
	}
	public Square(double len, double wi) {
		super(len,wi);
	}
	public double getLength() {
		return super.getLength();
	}
	public double getWide() {
		return super.getWide();
	}
	public double getPerimeter() {
		return super.getPerimeter();
	}
	public double getArea() {
		return super.getArea();
	}
}

class Rectangle extends Square{
	public Rectangle(double len, double wi) {
		super(len, wi);
	}
	public double getPerimeter() {
		return super.getPerimeter();
	}
	public double getArea() {
		return super.getArea();
	}
}

class Circle extends Shape{
	public Circle(double len) {
		super(len);
	}
	public double getPerimeter() {
		return 2*3.14159*super.getLength();
	}
	public double getArea() {
		return 3.14159*super.getLength()*super.getLength();
	}
}