Guava: Add Strings.nonEmpty(String)

[simon04]

Please add the following function to Strings in order to allow testing for non-empty strings in Streams or Optionals:

public static boolean nonEmpty(@Nullable String s) {
    return s != null && !s.isEmpty();
}

This follows the pattern of Objects.nonNull.

[jrtom]

I believe that Strings.isNullOrEmpty() does what you want, although the sense is reversed: re/api/docs/com/google/common/base/Strings.html#isNullOrEmpty-java.lang.String-

[simon04]

True, semantically the proposed function is the negation of Strings.isNullOrEmpty, but I'd like to .filter(Strings::nonEmpty) (using the :: shorthand notation).

[lowasser]

I can see the desire for a single method reference in the filter, but I'd be concerned about naming. Guava has been pretty firm about not _conflating_ nullness and emptiness...which would mean, what, neitherNullNorEmpty? A simpler possibility might be a notEmpty method, in which case you could do .filter(Objects::nonNull).filter(Strings::nonEmpty), or the like.

[jrtom]

I can understand wanting to do that, but I think it's highly unlikely that the Guava team is going to introduce a new method whose semantics are the negation of an existing method to save people from having to do this:

filter(s -> !isNullOrEmpty(s))

I mean, method references are nifty but lambdas make this pretty painless IMO.

[perceptron8]

Duplicate of #3064?

[perceptron8]

Also note that since Java 11 there is Predicate.not(Predicate), so you can negate/filter like this too:

filter(Objects::nonNull).filter(not(String::empty))