为什么我调用了子类的方法，给子类的属性赋了值，输出的结果却只为零
测试类
package imooc.com;public class Tt { public static void main(String[] args) {
// TODO Auto-generated method stub
AA aa=new AA();
AA n=new BB();
n.a=1;n.b=2;
double d=n.Nn();
System.out.println(d);
}}类1
package imooc.com;
public class AA {
public double a;
public double b;
public double Nn(){
double s=0;
return s;
}
}
类2
package imooc.com;
public class BB extends AA {
public double a;
public double b;
public double Nn(){
double s=0;
s=a+b;
return s;
}
}
