– 定義一個圓類(Circle)，其所在的包為bzu.info.software；定義一個圓柱類Cylinder，其所在的包為bzu.info.com；定義一個主類A，其所在的包也為bzu.info.com，在A中生成一個Cylinder對象，並輸出其體積。編譯並運行該類。
– 試著改變求體積方法的訪問權限，查看並分析編譯和運行結果
– 把Cylinder類和A類置於不同的包中，通過對求體積方法設置不同的訪問權限，查看並分析編譯和運行結果

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;
}
}

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.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("底面半徑："+circle.getR()+",圓柱的高："
+cylinder.getHeight()+",圓柱的體積："+s);
}
}

定義一個圓類(Circle)，其所在的包為bzu.info.software......