I’m working on a new codebase and I’m wondering, since all non-optional parameters in my code throw an IllegalArgumentException when passed null, does it even make sense to use annotations like @NonNull? Or is it better to expect programmers know I always use Optional to indicate not passing in any value is a valid action here? (Of course assuming I also say that in javadoc, etc.)
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1@NonNull can be used by your IDE, your exception not.user180100– user1801002017-09-07 17:08:43 +00:00Commented Sep 7, 2017 at 17:08
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4Many think that Optional should not be used for parameters.Andy Turner– Andy Turner2017-09-07 17:08:46 +00:00Commented Sep 7, 2017 at 17:08
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2 Answers
You can pass a null to a parameter that expects an Optional so you could argue that @NonNull is still useful.
Personally I think @NonNull becomes redudant because if you call a method that expects an Optional you would pass Optional.empty() and never null when the value is absent. Keep in mind that java conventions discorages the use of Optional in parameters.
I disagree with this convention as Optional already conveys the meaning that the underlying method is prepared to deal with the absence of a value.
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Ultimately this is a matter of opinion and preference, but I don't think @NonNull is necessary if it's well established that your code is null-hostile. Guava takes such an approach and uses a @Nullable annotation to indicate the occasional exception.
