Java 重写小练习

 1 package com.bytezero.inherit3;
 2
 3 public class CylinderTest
 4 {
 5     public static void main(String[] args)
 6     {
 7
 8         Cylinder cy = new Cylinder();
 9         cy.setRadius(2.2);
10         cy.setLength(3.3);
11         cy.findVolume();
12         System.out.println("圆柱的体积为"+cy.findVolume());
13
14
15         //没重写时
16 //        cy.findArea();
17 //        System.out.println("圆柱的底面积为"+ cy.findArea());
18 //
19         //重写以后
20         cy.findArea();
21         System.out.println("圆柱的表面积为"+ cy.findArea());
22
23
24
25
26
27
28
29     }
30 }

 1 package com.bytezero.inherit3;
 2
 3 public class Circle
 4 {
 5     private double radius;
 6
 7     public Circle()
 8     {
 9          this.radius = 1.0;
10     }
11
12
13     public void setRadius(double radius)
14     {
15         this.radius = radius;
16     }
17     public double getRadius()
18     {
19         return  radius;
20     }
21
22     public double findArea()
23     {
24         return Math.PI * radius*radius;
25     }
26
27
28
29
30 }

 1 package com.bytezero.inherit3;
 2
 3 public class Cylinder extends Circle
 4 {
 5
 6     private double length;
 7
 8     public Cylinder()
 9     {
10         double length = 1.0;
11     }
12
13     public void setLength(double length)
14     {
15         this.length  = length;
16     }
17
18
19     public double getLength()
20     {
21         return length;
22     }
23
24     public double findVolume()
25     {
26         //return Math.PI * getRadius() * getRadius() *length;
27         return Math.PI * getRadius() * getRadius() *getLength();
28        // return findArea() * getLength();
29
30     }
31
32     @Override
33     //返回圆柱的表面积
34     public double findArea()
35     {
36         return Math.PI *getRadius() *getRadius() *2+
37                 2*Math.PI *getRadius()*getLength();
38     }
39
40
41
42
43 }