Java开发网 - 关于对象在继承关系中的转变的问题。

Topic: 关于对象在继承关系中的转变的问题。

1.关于对象在继承关系中的转变的问题。

Posted by: caoguanghui
Posted on: 2006-03-18 21:39

程序如下：
class SuperClass{
private int x=100;
public int getX() {
return x;
}
}
class Subbie extends SuperClass{
private int y=200;
public int getY(){
return y;
}
}
public class ObjectConvert{
public static void main(String[] arg){
SuperClass superA = new SuperClass(),superB;
Subbie subA=new Subbie(),subB;
(new ObjectConvert()).useSubAsSuper(subA);
superB=subA;
System.out.println("superB.getX: "+superB.getX());
subB=(Subbie)superB;
System.out.println(subB.getX+" "+subB.getY()); //编译的时候显示这行出错提示为 cannot resolve symbol.
}
public void useSubAsSuper(SuperClass x){
System.out.println(x.getX()+"!!!!!!");
}
}
难道是 subB=(Subbie)superB; 一行出错？但是书上讲可以将指向子类对象地址的父类对象强制转换成子类对象的啊！

2.Re:关于对象在继承关系中的转变的问题。 [Re: caoguanghui]	Copy to clipboard
Posted by: caoguanghui Posted on: 2006-03-19 15:51 没有热心人吗? 小弟真的是思考很就也不得其解才放上来的啊!

3.Re:关于对象在继承关系中的转变的问题。 [Re: caoguanghui]	Copy to clipboard
Posted by: Skybus Posted on: 2006-03-19 18:30 You should be more careful in the future! System.out.println(subB.getX()+ " " + subB.getY());

4.Re:关于对象在继承关系中的转变的问题。 [Re: caoguanghui]	Copy to clipboard
Posted by: jackyangf Posted on: 2006-03-20 17:42 .... 这样编译也不能通过啊？