Question

I’m looking to have a collection of objects that implement a certain interface, but I’d like to only have one per concrete type within the collection.

collection of implementers of dog:
 - instance of dachshund
 - instance of beagle
 - instance of corgi

In .NET, there’s a “KeyedByTypeCollection”. Does something similar exist in Java in such a way that I could use it on Android?

Thanks!

Answer 1

You should look at generics. E.g.:
List<Dogs> dogList = new ArrayList<Dogs>();

EDIT: to have only unique instances in your collection, you should use Set<Dogs> dogList = new HashSet<Dogs>();