The Collections.singleton()
method returns a Set
with that single argument instead of a Collection
.
Why is that so? From what I can see, apart from Set
being a subtype of Collection
, I can see no advantage... Is this only because Set
extends Collection
anyway so there is no reason not to?
And yes, there is also Collections.singletonList()
but this is another matter since you can access random elements from a List
with .get()
...
I'm not sure there's a "benefit" or "advantage" per se? It's just the method that returns a singleton Set
, and happens to be the default implementation when you want a singleton Collection
as well, since a singleton Collection
happens to be a mathematical set as well.