主题：[推荐]Java授课视频第七课：面向对象——继承

class Point {
        private int x;
        private int y;

        public Point() {

        }

        public Point(int x, int y) {
                setPoint(x, y);
        }

        public int getX() {
                return x;
        }

        public void setX(int x) {
                this.x = x;
        }

        public int getY() {
                return y;
        }

        public void setY(int y) {
                this.y = y;
        }

        public void setPoint(int x, int y) {
                setX(x);
                setY(y);
        }

        public String toString() {
                return "(" + x + "," + y + ")";
        }

}

class Circle extends Point {
        protected int r;

        public Circle() {

        }

        public Circle(int x, int y, int r) {
                setCircle(x, y, r);
        }

        public int getR() {
                return r;
        }

        public void setR(int r) {
                this.r = r;
        }

        public void setCircle(int x, int y, int r) {
                setPoint(x, y);
                setR(r);
        }

        public String toString() {
                return String.valueOf(Math.PI * r * r);
        }

}

class Cylinder extends Circle {
        private int h;

        public Cylinder() {

        }

        public Cylinder(int x, int y, int r, int h) {
                setCylinder(x, y, r, h);
        }

        public int getH() {
                return h;
        }

        public void setH(int h) {
                if (h > 0)
                        this.h = h;
        }

        public void setCylinder(int x, int y, int r, int h) {
                setCircle(x, y, r);
                setH(h);
        }

        public String toString() {
                return String.valueOf(Math.PI*r*r*h);
                //return String.valueOf(Double.parseDouble(super.toString()) * h);
        }

}

public class Exec {
        public static void main(String[] args) {
                Cylinder c=new Cylinder(1,2,3,4);
                System.out.println(c);