image.png

    1. package com.atguigu.exercise2;
    2. public class Circle {
    4.     //属性
    5.     private double radius;//半径
    7.     //构造器
    8.     public Circle(){
    9.   radius = 1.0;
    10.     }
    12.     public Circle(double radius){
    13.   this.radius = radius;
    14.     }
    15.     //方法
    16.     public void setRadius(double radius){
    17.   this.radius = radius;
    18.     }
    20.     public double getRadius(){
    21.   return radius;
    22.     }
    24.     //返回圆的面积
    25.     public double findArea(){
    26.   return Math.PI*radius*radius;
    27.     }
    28. }
    1. package com.atguigu.exercise2;
    2. public class Cylinder extends Circle{
    3.     //属性
    4.     private double length;//高
    6.     //构造器
    7.     public Cylinder(){
    8.   length = 1.0;
    9.     }
    11.     public Cylinder(double length){
    12.   this.length = length;
    13.     }
    15.     //方法
    16.     public double getLength(){
    17.   return length;
    18.     }
    20.     public void setLength(double length){
    21.   this.length = length;
    22.     }
    24.     public double findVolume(){
    25.   //return Math.PI*getRadius()*getRadius()*getLength();
    26.   return findArea()*getLength();
    27.     }
    28. }
    1. package com.atguigu.exercise2;
    2. public class CylinderTest {
    3.     public static void main(String[] args) {
    5.   Cylinder cd = new Cylinder();
    6.   cd.setRadius(2);
    7.   cd.setLength(5);
    8.   cd.findVolume();
    9.   System.out.println("圆柱的体积是：" + cd.findVolume());
    10.     }
    11. }