I have an unexpected situation in a project in which all types extending one class are packed into a Java collection; but only a specific extension of that class contains an additional method. Let's call it "also()"; and let me be clear that no other extension has it. Right before performing one task on every item in that collection, I need to call also() on every item that implements it.
The easiest way forward is this:
stuff.stream().filter(item -> item instanceof SpecificItem) .forEach(item -> ((SpecificItem)item).also())); stuff.stream().forEach(item -> item.method());
It works fine, but I'm not comfortable with the "instanceof" in there. That's generally a marker of bad code smell. It is very possible that I will refactor this class just to get rid of it. Before I do something that dramatic, though, I thought I would check with the community and see if someone with more experience with either Streams or Collections had a simpler solution.
As an example (certainly nonexclusive), is it possible to get a view of a collection that filters entries by class?
SpecificItem, and this is the proper way to specify the predicate, then why are you squeamish about the
SpecificItem's implementation doesn't just call
Iterabledoesn't have a
stream()method, but you can call
forEach()directly on an