爱知识1的博客

class Circle { final static double PI=3.14;//声明常量 private static double dbRadius=1;//声明公享变量 public Circle(double radius){ dbRadius=radius; } public double Area(){ double area; area=PI*dbRadius*dbRadius; return area; } public static double Perimeter (){//添加静态方法 double perimeter ; perimeter=2*PI*dbRadius; return perimeter; } } public class CircleDemo1{ public static void main(String[] args) { Circle cir=new Circle(3.5); //调用实例方法计算圆的面积 System.out.println("圆的面积："+cir.Area()); //调用静态方法计算圆的周长 System.out.println("圆的周长："+Circle.Perimeter()); } }