Java 8 maps the collection. If the collection is empty, add the default value

I have a use case, and I must return a set containing at least 1 element The incoming collection may contain 0 or more elements

So this can be done easily

Set<ObjectB> setOfB = collectionOfA.isEmpty() ? 
        new HashSet<ObjectB>() {{ add(new ObjectB()); }}  : 
        collectionOfA
           .stream()
           .map(item -> new ObjectB(item))
           .collect(Collectors.toSet());

But

I'm also trying to take this opportunity to become more familiar with Java 8 tools and functions, so I'm trying to see if I can do it in a more Java 8 like way without conditional testing

Thank you very much for your comments and suggestions!

Solution

I think you've made it as simple as possible Remember, Java 8 is still the same language; Don't try too hard to make everything work

One of the improvements I made to your code is to use collections Singleton (New objectb()) instead of clumsy and problematic double bracket initialization