Generics or not Generics

Question

Basically I have a custom List class that contains different fruits. Assume that each fruit has an ID number that is stored in the list.

Is it better to have:

new AppleList();
new OrangeList();
new LemonList();

or

new FruitList<Fruit.Apple>();
new FruitList<Fruit.Orange>();
new FruitList<Fruit.Lemon>();

Things to consider:

• All IDs are of type int.
• The type of the fruit will not affect the implementation of the List itself. It will only be used by the client of the list, like an external method, etc.

I would like to use the one that is clearer, better in design, faster, more efficient, etc. Additionally if these above 2 techniques are not the best, please suggest your ideas.

EDIT: Btw Fruit is an enum if that wasn't clear.

Answer 1

Use a combo:

public class AppleList : FruitList<Apple> { ... }
public class OrangeList : FruitList<Orange> { ... }
public class LemonList : FruitList<Lemon> { ... }

Put the common logic in the base list class:

public class FruitList<T> : List<T>
    where T : IFruit 
{ ... }

Answer 2

If you use generics, is there a purpose to create the FruitList type? Could you just use List?

There won't be much difference in performance, so I say why create three different classes when one would do the same exactly thing? Use the generic solution.