CoreJava/exp4/ShapeDemo.java

package exp4;

abstract class Shapes  {
    public  int x,y; //x，y为的坐标  
    public  int width,height;   
    public  Shapes(int x,int y,int width,int height)  {    
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;
    }   
    public abstract double getArea();  
    public abstract double getPerimeter(); 
    public abstract void show();
    }

    class Rectangle extends Shapes{
        double a;
        double b;

        Rectangle(double a, double b){
            super(0, 0, 0, 0);
            this.a=a;
            this.b=b;
        }

        public double getArea(){
            return a*b;
        }

        public double getPerimeter(){
            return (a+b)*2;
        }

        public void show(){
            System.out.println("矩形  长:"+this.a+"宽:"+this.b);
        }
    }

    class Circle extends Shapes{
        double radius;//半径
        
        Circle(double radius){
            super(0, 0, 0, 0);
            this.radius=radius;
        }
        
        public double getArea(){
            return 3.14159265324*radius*radius;
        }

        public double getPerimeter(){
            return 3.14159265324*radius*2;
        }

        public void show(){
            System.out.println("圆  半径:"+this.radius);
        }
    }


public class ShapeDemo {
    public static void main(String[] args){
        Shapes r = new Rectangle(2, 3);
        Shapes c = new Circle(5);

        r.show();
        System.out.println("面积:"+r.getArea()+"  周长:"+r.getPerimeter()+"\n");

        c.show();
        System.out.println("面积:"+c.getArea()+"  周长:"+c.getPerimeter()+"\n");
         
    }
}