子类会继承父类对于接口的实现

 项目截图：

实现代码：

package exercise2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

interface CircleShape {
    double PI = 3.14159;

    double area(double radius);
}

class Circle implements CircleShape {
    int radius;

    public Circle(int r) {
        radius = r;
    }

    public double perimeter() {
        return (2 * PI * radius);
    }

    @Override
    public double area(double radius) {
        return (PI * radius * radius);
    }
}

class Cylinder extends Circle implements CircleShape {// 子类会继承父类对于接口的实现
    int heigh;
    int radius;

    public Cylinder(int r, int h) {
        super(r);
        heigh = h;
    }

    public double baseAera(double radius) {
        return area(radius);
    }

    public double area1(double radius) {
        return (heigh * super.perimeter() + 2 * area(radius));
    }

    public double volume(double radius) {
        return (heigh * area(radius));
    }
}

public class Ex13_2 {
    public static void main(String[] args) throws IOException {
        int r1, r2;
        String t;
        System.out.println("请输入圆cir1和cir2的半径r1,r2");
        BufferedReader scan = new BufferedReader(new InputStreamReader(
                System.in));
        t = scan.readLine();
        r1 = Integer.parseInt(t);
        t = scan.readLine();
        r2 = Integer.parseInt(t);
        Circle cir1 = new Circle(r1);
        Circle cir2 = new Circle(r2);
        System.out.println("圆cir1的面积是" + cir1.area(r1) + "	周长是："
                + cir1.perimeter());
        System.out.println("圆cir2的面积是" + cir1.area(r2) + "	周长是："
                + cir2.perimeter());
        int h1, h2;
        System.out.println("请输入圆柱cy1的半径和高：");
        t = scan.readLine();
        r1 = Integer.parseInt(t);
        t = scan.readLine();
        h1 = Integer.parseInt(t);
        Cylinder cy1 = new Cylinder(r1, h1);
        System.out.println("cy1的底圆面积是：" + cy1.baseAera(r1));
        System.out.println("cy1的体积是：" + cy1.volume(r1) + "	表面积是："
                + cy1.area1(r1));

        System.out.println("请输入圆柱cy2的半径和高：");
        t = scan.readLine();
        r2 = Integer.parseInt(t);
        t = scan.readLine();
        h2 = Integer.parseInt(t);
        Cylinder cy2 = new Cylinder(r2, h2);
        System.out.println("cy2的底圆面积是：" + cy2.baseAera(r1));
        System.out.println("cy2的体积是：" + cy2.volume(r1) + "	表面积是："
                + cy2.area1(r2));
    }

}