例题4-2 使用类Circle求圆的面积

代码：class Circle{
  double radius;
  double getArea(){
   double area=3.14*radius*radius;
   return area;
   }
  }
public class Example4_2{
  public  static void main(String[] args){
    Circle circle =new Circle();
   circle.radius=12.23;
   double area=circle.getArea();
   System.out.printf("半径是%5.3f的圆的面积是：\n%5.3f\n",circle.radius,area);
   }
  }