Generic types

[O Joseph]

hi,
is it possible to use generic types for a vector that stores different objects e.g. other vectors and Color?

[Jeff Albertson]

You would have to make the List's type a common base type. In the case of Color and Vector, it would be Object

[O Joseph]

I have tried that but the compiler complains they are incompatible types

[Jeff Albertson]

Works for me:

import java.awt.Color;
import java.util.*;
 
public class Test {
public static void main(String[] args) {
List<Object> list = new ArrayList<Object>();
list.add(Color.RED);
list.add(new ArrayList<Integer>());
System.out.println(list);
}
}

[Ken Blair]

If you're referring to not having to cast to/from the Object then no. In order to use generics they must have a common type and casting to/from that type is the only thing you can avoid. I.e. You can't do Color c = vector.get(1) with a Vector<Object>. All the compiler knows is that the Vector contains Objects, you have to do the down cast yourself.

[Layne Lund]

Originally posted by Jo Onibokun:
I have tried that but the compiler complains they are incompatible types

Can you please post the code and compiler error? We can only guess what your problem is without these details.

Layne