定义一个圆类(Circle)

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。

– 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.com;  import bzu.info.software.Circle;  public class A {        public static void main(String[] args) {          Cylinder cylinder=new  Cylinder();          Circle circle=new Circle(10);          circle.setR(10);          cylinder.setCircle(circle);            cylinder.setHeight(20);           double s=cylinder.getVolme();          System.out.println("底面半径："+circle.getR()+",圆柱的高："                    +cylinder.getHeight()+",圆柱的体积："+s);       }    } 

package bzu.info.com;  import bzu.info.software.Circle;  public class Cylinder {  Circle circle;  double height;  public Circle getCircle() {      return circle;  }  public void setCircle(Circle circle) {        this.circle = circle;  }  double getVolme() {      return circle.getArea()*height;  }  public double getHeight() {        return height;    }  public void setHeight(double height) {        this.height = height;    }    }

package bzu.info.software;    public class Circle {  double r,area;  public Circle(double r){      this.r=r;  }  public void setR(double r) {      this.r=r;  }  public double getR() {      return r;  }  public double getArea() {      area=3.14*r*r;      return area;  }  }