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 }