circle.java

java教程中的编程实例

public class Circle extends Shape{
               double r;
               public Circle(double x){
                  r=x;  }
               public double area(){
                      double s;
                      s=3.14*r*r;
                      return s;
                          }
               public double perimeter(){
                       double p;
                       p=2*3.14*r;
                       return p;
                           }
               public String getabout(){
                   return "this is circle radius is:"+r;
                             }
                }