Instanceof vs. enumeration

Question

Which is considered to be better: using instanceof to determine a type of object at runtime or some sort of enumeration?
Thank you.

Answer 1

The problem is this: I have a series of objects that, logically, derive from a base class
public abstract class MyClass
    public abstract foo(MyClass obj);
}However, these classes interact with each other in different ways depending on what the class is:
public class MyChildClass1 extends MyClass
    private int j;
    public foo(MyClass obj)
        // default case
    public foo(MyChildClass1 obj)
        // do something in respect to MyChildClass1
    public foo(MyChildClass2 obj)
        // do something in respect to MyChildClass2
public class MyChildClass2 extends MyClass
    private int i;
    public foo(MyClass obj)
        // default case
    public foo(MyChildClass1 obj)
        // do something in respect to MyChildClass1
    public foo(MyChildClass2 obj)
        // do something in respect to MyChildClass2
}At this point, everything works out nicely. The problem is that when I try to store all of the objects into a Collection and call foo() with another object from the Collection, I lose the type of the object, and I call the wrong method.
In hindsight, I guess the real question is that would this be the best design? If not, what is wrong and how should I reapproach this problem.
Thank you again for your help!
Edited by: darkwraith on May 12, 2008 9:13 AM
Clarified code.