java多态代码

class Shape {
    public double perimeter = 0.0;
    public double perimeter(){
    return perimeter;
    }
}

class Circle extends Shape{
    public double r = 0.0;
    public Circle(double r){
        this.r=r;        
    }
    public double perimeter(){
        perimeter = 2*3.14*r*r;
        return perimeter;
    }
}

class Square extends Shape{
    public double l = 0.0;
    public double w = 0.0;
    public Square(double l,double w){
        this.l=l;
        this.w=w;
    }
    public double perimeter(){
        perimeter = 2*(l+w);
        return perimeter;
    }
}

class Perimeter{
    public static void main(String[] args){
        Shape s1 = new Circle(2.2);
        System.out.println(s1.perimeter());
        s1 = new Square(2,3);
        System.out.println(s1.perimeter());
        System.out.println(s1.perimeter);
    }
}