Determining the type of an object?

[H Melua]

Hello

I was wondering, if I have an interface that is implemented by several classes, (lets say Shape)
and I've created an object of this type like this

Shape s;
s = new Rectangle();
// after few method calls I change the type of s to be triangle
s = new Triangle();

then how can I determine what type of shape s in this case? in other words, how can I know if s is now a triangle or rectangle?

is there a method in Java that checks the actual type of the object?

Thanks
HannaH

[Pawan Arora]

I think declaring a method in another class, which will accept the argument of superclass and it's subclass at runtime is the fine solution of it. This is also called polymorphism.
[ October 24, 2008: Message edited by: Pawan Arora ]

[Larry Frissell]

You can use:

s.getClass()    

[Bill Shirley]

and then you can call isAssignableFrom

[H Melua]

Thanks guys very much
That works

[Ilja Preuss]

You can also use the instanceof operator.

But in general, using these techniques is a sign for a design that doesn't make full use of the advantages of OOP, especially polymorphism.

Why do you feel the need to do it?