题3

[java]代码库

class Circle {
    protected double radius;
    public Circle(double r){
        radius=r;
    }
    public double getArea(){
        return Math.PI*radius*radius;
    }
}
class Cylinder extends Circle{
    private double height;
    public Cylinder(double r, double h){
        super(r);
        height = h;
    }
    public double getVolume(){
        return super.getArea()*height;
    }
}
public class Main {
    public static void main(String[] args) {
        Cylinder c = new Cylinder(5.0,10.0);
        System.out.println(c.getArea());
        System.out.print(c.getVolume());
    }
}