Description

定義一個形狀類Shape，提供計算周長getPerimeter()和麵積getArea()的函式
定義一個子類正方形類Square繼承自Shape類，擁有邊長屬性，提供建構函式，能夠計算周長getPerimeter()和麵積getArea()
定義一個子類長方形類Rectangle繼承自Square類，擁有長、寬屬性，提供建構函式，能夠計算周長getPerimeter()和麵積getArea()
定義一個子類圓形類Circle繼承自Shape，擁有半徑屬性，提供建構函式，能夠計算周長getPerimeter()和麵積getArea()

在main函式中，分別構造三個Shape類的變數，分別指向一個Square、Rectangle、Circle物件，並輸出他們的周長、面積.

import java.util.Scanner;

public class Main {
	public static void main(String [] args) {
		Scanner sc = new Scanner(System.in);
		double k = sc.nextDouble();
		Square s = new Square(k);
		System.out.println(String.format("%.2f",s.getPerimeter())+" "+String.format("%.2f", s.getArea()));
		
		k = sc.nextDouble();
		double l = sc.nextDouble();
		Rectangle r = new Rectangle(k,l);
		System.out.println(String.format("%.2f",r.getPerimeter())+" "+String.format("%.2f", r.getArea()));
			
		k = sc.nextDouble();
		Circle c = new Circle(k);
		System.out.println(String.format("%.2f",c.getPerimeter())+" "+String.format("%.2f", c.getArea()));
		
		
		sc.close();
	}

}

class Shape{
	//int Bc;
	//Shape(){}
	double getPerimeter() {
		return 0;
	}
	
    double getArea() {
    	return 0;
    }
}
class Square extends Shape{
	double l ;//長
	Square(double l){
		this.l = l;
	}
	double getPerimeter() {
		return l*4;
	}
	
	double getArea() {
		return l*l;
	}
	
}

class Rectangle extends Square{

	double h;//寬
	Rectangle(double l,double h) {
		super(l);
		this.h = h;
		// TODO Auto-generated constructor stub
	}
	
	double getPerimeter() {
		return 2.0*(l+h);
	}
	
	double getArea() {
		return l*h;
	}
	
}

class Circle extends Shape{
	double r;//半徑
	Circle(double r){
		this.r = r;
	}
	
	double getPerimeter() {
		return 2.0*Math.PI*r;
	}
	
	double getArea() {
		return Math.PI*r*r;
	}
	
}