Package与Import

课堂练习6：
⦁ 定义一个圆类(Circle)，其所在的包为bzu.info.software；定义一个圆柱类Cylinder，其所在的包为bzu.info.com；定义一个主类A，其所在的包也为bzu.info.com，在A中生成一个Cylinder对象，并输出其体积。编译并运行该类。

package bzu.info.com;import bzu.info.software.Circle;public class Cylinder {double height;Circle c;Cylinder (double h,Circle cc){height=h;c=cc;}public double volume(){return height*c.areas();}}

package bzu.info.software;public class Circle {double radius;public Circle(double r){radius=r;}public double areas(){return 3.14*radius*radius;}}

package bzu.info.com;import bzu.info.software.Circle;public class A {public static void main(String[] args) {// TODO 自动生成的方法存根Circle c=new Circle(2);Cylinder cylinder =new Cylinder(2.0,c);System.out.println("圆柱的体积为："+cylinder.volume());}}

⦁ 试着改变求体积方法的访问权限，查看并分析编译和运行结果

⦁ 把Cylinder类和A类置于不同的包中，通过对求体积方法设置不同的访问权限，查看并分析编译和运行结果

package bzu.info.software;public class Circle {double radius;public Circle(double r){radius=r;}public double areas(){return 3.14*radius*radius;}}

package bzu.info.com;import bzu.info.software.Circle;public class Cylinder {double height;Circle c;public Cylinder (double h,Circle cc){height=h;c=cc;}public double volume(){return height*c.areas();}}

package bzu.info.hello;import bzu.info.com.Cylinder;import bzu.info.software.Circle;public class A {public static void main(String[] args) {// TODO 自动生成的方法存根Circle c=new Circle(2);Cylinder cylinder =new Cylinder(2.0,c);System.out.println("圆柱的体积为："+cylinder.volume());}}