package 继承;

public class Example5_18{
 public static void main(String args[]) {
 //创建三个Shape对象
 Shape shape[] = new Shape[3];
 shape[0] = new Circle(50, 50, 40);
 shape[1] = new Rectangle(0, 0, 40, 30);
 shape[2] = new RectangleEx(20, 30, 40, 30, 5);
 //创建三个Shape对象的信息数组
 String ShapeName[] = new String[3];
 ShapeName[0] = "圆Circle(50, 50, 40)";
 ShapeName[1] = "矩形Rectangle(0, 0, 40, 30)";
 ShapeName[2] = "圆角矩形RectangleEx(20, 30, 40, 30, 5)";
 //求面积和周长
 for(int i = 0; i < shape.length; i++) {
 System.out.println(ShapeName[i] + "的面积="								+ shape[i].area());
 System.out.println(ShapeName[i] + "的周长=" + shape[i].perimeter());
 System.out.println();
 }
 }
}
class Shape{
 public final double PI = 3.141592654;
 double area(){ return 0; };
 double perimeter(){ return 0; };
}
//子类Circle的声明
class Circle extends Shape{
 int centerX; //圆心X坐标
 int centerY; //圆心Y坐标
 int radius; //圆的半径

 public Circle(int x, int y, int r) {
 super(); 
 centerX = x;
 centerY = y;
 radius = r;
 }
 public double area() {
 return (int)(PI * radius * radius );
 }
 public double perimeter() {
 return (int)(2 * PI * radius);
 }
}
class Rectangle extends Shape{
 int left; //矩形左上角X坐标
 int top; //矩形左上角Y坐标
 int width; //矩形长度
 int height; //矩形宽度

 public Rectangle(int l, int t, int w, int h) {
 super();
 left = l;
 top = t;
 width = w;
 height = h;
 }
 public double area() {
 return (int)(width * height);
 }
 public double perimeter() {
 return (int)((width + height) * 2);
 }
}
class RectangleEx extends Rectangle{
 int radius; //圆角半径

 public RectangleEx(int l, int t, int w, int h, int r){
 super(l, t, w, h); 
 radius = r;
 }
 public double area() {
 return (int)(super.area() - (4 - PI) * radius* radius);
 }
 public double perimeter() {
 return (int)((width + height)*2 - 8*radius + 2*PI*radius);
 }
}