package demo1package; public class Cylinder { private double radius; private double pi; public void setnumber(double r,double p){//公共方法用于对私有成员进行访问 if(r>0 && p>0){ radius=r; pi=p; }else System.out.println("您的输入有误"); } double area(){ return pi*radius*radius; } }
package demo1package; public class text1 { public static void main(String[] args) { // TODO Auto-generated method stub Cylinder cylinder=new Cylinder(); cylinder.setnumber(3,3.14); System.out.println("圆的面积是:"+cylinder.area()); } }