子类会继承父类对于接口的实现

项目截图：

实现代码：

 1 package exercise2;
 2
 3 import java.io.BufferedReader;
 4 import java.io.IOException;
 5 import java.io.InputStreamReader;
 6
 7 interface CircleShape {
 8     double PI = 3.14159;
 9
10     double area(double radius);
11 }
12
13 class Circle implements CircleShape {
14     int radius;
15
16     public Circle(int r) {
17         radius = r;
18     }
19
20     public double perimeter() {
21         return (2 * PI * radius);
22     }
23
24     @Override
25     public double area(double radius) {
26         return (PI * radius * radius);
27     }
28 }
29
30 class Cylinder extends Circle implements CircleShape {// 子类会继承父类对于接口的实现
31     int heigh;
32     int radius;
33
34     public Cylinder(int r, int h) {
35         super(r);
36         heigh = h;
37     }
38
39     public double baseAera(double radius) {
40         return area(radius);
41     }
42
43     public double area1(double radius) {
44         return (heigh * super.perimeter() + 2 * area(radius));
45     }
46
47     public double volume(double radius) {
48         return (heigh * area(radius));
49     }
50 }
51
52 public class Ex13_2 {
53     public static void main(String[] args) throws IOException {
54         int r1, r2;
55         String t;
56         System.out.println("请输入圆cir1和cir2的半径r1,r2");
57         BufferedReader scan = new BufferedReader(new InputStreamReader(
58                 System.in));
59         t = scan.readLine();
60         r1 = Integer.parseInt(t);
61         t = scan.readLine();
62         r2 = Integer.parseInt(t);
63         Circle cir1 = new Circle(r1);
64         Circle cir2 = new Circle(r2);
65         System.out.println("圆cir1的面积是" + cir1.area(r1) + "\t周长是："
66                 + cir1.perimeter());
67         System.out.println("圆cir2的面积是" + cir1.area(r2) + "\t周长是："
68                 + cir2.perimeter());
69         int h1, h2;
70         System.out.println("请输入圆柱cy1的半径和高：");
71         t = scan.readLine();
72         r1 = Integer.parseInt(t);
73         t = scan.readLine();
74         h1 = Integer.parseInt(t);
75         Cylinder cy1 = new Cylinder(r1, h1);
76         System.out.println("cy1的底圆面积是：" + cy1.baseAera(r1));
77         System.out.println("cy1的体积是：" + cy1.volume(r1) + "\t表面积是："
78                 + cy1.area1(r1));
79
80         System.out.println("请输入圆柱cy2的半径和高：");
81         t = scan.readLine();
82         r2 = Integer.parseInt(t);
83         t = scan.readLine();
84         h2 = Integer.parseInt(t);
85         Cylinder cy2 = new Cylinder(r2, h2);
86         System.out.println("cy2的底圆面积是：" + cy2.baseAera(r1));
87         System.out.println("cy2的体积是：" + cy2.volume(r1) + "\t表面积是："
88                 + cy2.area1(r2));
89     }
90
91 }