Comments on: Put Your Java 8 Method References to Work

By: Per Minborg

Per Minborg — Mon, 11 Sep 2017 16:32:09 +0000

Casting can be used but I think it does not look so good. You would need to write

Stream.of("A", "", "B").filter(((Predicate<String>)String::isEmpty).negate()).count();

if you do not want compiler warnings and it is a bit cluttery. But that is my personal opinion only. I should have mentioned cast in the article. Thanks for your comment!

By: Kunda

Kunda — Mon, 11 Sep 2017 13:49:55 +0000

Actually, Java provides a simple way to do this - the explicit cast:

Stream.of("A", "", "B").filter(((Predicate)String::isEmpty).negate()).count();

By: Per Minborg

Per Minborg — Tue, 05 Sep 2017 16:47:03 +0000

Yes. I think this is also a good way to do it. Thanks for you suggestion.

By: Anonymous

Anonymous — Tue, 05 Sep 2017 09:01:36 +0000

Why not just have a "not" like this:

public static final T Predicate T not( Predicate T predicate ) {
return predicate.negate();
}

This you can use like:

Stream.of("A", "", "B").filter(not(String::isEmpty)).count();

By: Unknown

Unknown — Fri, 28 Jul 2017 04:22:46 +0000

"as(String::isEmpty).negate()"

That's pretty brilliant. A real shame that java doesn't offer a simple way to do this.. seems like a pretty obvious need.