package?yu.zhang;

public?abstract?class?Shape?{
	public?abstract?double?perimeter();
	public?abstract?double?area();
}

package?yu.zhang;

public?class?Rectangle?extends?Shape{
	public?double?i?=?3;????//定義矩形的長
	public?double?j?=?2;	//定義矩形的寬
	public?double?perimeter(){
		return(i+i+j+j);
	}
	public?double?area(){
		return(i*j);
	}
}

package?yu.zhang;

public?class?Circle?extends?Shape{
	private?double?r?=?4;???//定義圓的半徑
	public?double?perimeter(){
		return(3.14*r*2);
	}
	public?double?area(){
		return(3.14*r*r);
	}
}

package?yu.zhang;

public?class?main?{

	public?static?void?main(String[]?args)?{
		//?TODO?Auto-generated?method?stub
		Shape?rec?=?new?Rectangle();
		Shape?cir?=?new?Circle();
		double?recPerimeter?=?rec.perimeter();????//求矩形周長
		double?recArea?=?rec.area();?????//求矩形面積
		System.out.println("矩形的周長是："?+?recPerimeter);
		System.out.println("矩形的面積是："?+?recArea);
		
		double?cirPerimeter?=?cir.perimeter();????//求圓形的周長
		double?cirArea?=?cir.area();????//求圓形的面積
		System.out.println("圓形的周長是："?+?cirPerimeter);
		System.out.println("圓形的面積是："?+?cirArea);
	}

}