[bhuber]

It doesn't fully solve the problem, but @lombok.NonNull helps a lot. It makes it clear which properties shouldn't be null, and catches NPEs closer to the source. Incidentally, lombok in general does wonders for boilerplate reduction.

https://projectlombok.org/

[topspin]

> but @lombok.NonNull helps a lot

Which @NonNull? There's javax.validation.constraints.NotNull, org.springframework.lang.NonNull, org.checkerframework.checker.nullness.qual.NonNull, org.jetbrains.annotations.NotNull, android.support.annotation.NonNull and a bunch of others[1]. The proliferation of Not|NonNull is evidence that I'm right, no matter how hard I get downed on HN.

[1] https://stackoverflow.com/questions/35892063/which-nonnull-j...

[bhuber]

I didn't say it wasn't a problem - if I could wave a magic wand and get rid of the concept of null in Java I would. That isn't what we're discussing though - you said, "The biggest thing missing in Java is an answer for the billion-dollar mistake [- NPEs]". I've provided what I consider to be at least a partial answer. If you care about avoiding NPEs in Java, it's a pretty good solution.

Realistically, null is so fundamental to the Java language that removing it would arguably result in a different language entirely. Certainly all existing java codebases would have to be refactored. The same goes for exceptions. That's obviously not an option when one of your primary selling points is backwards compatibility, so I'm not really sure what kind of solution you're looking for here.

The answer to your SO link notwithstanding, I would argue the @lombok.NonNull is at least one of the best options, as it actually generates a null check that is executed at runtime. This makes it more powerful than most of the other solutions.

[topspin]

> Realistically, null is so fundamental to the Java language that removing it would...

Again, as jayd16 pointed out a solution has been retrofitted to C#, Java's great nemesis. I don't accept the argument that this is somehow infeasible. Just make null assignments (including potential ones coming from libraries) an error and allow this feature to be scoped to your source files. Eventually the practice becomes ubiquitous. It's been done again and again in many languages and their various 'strict' modes.

The only actual problem here is that Java language developers aren't feeling sufficient pressure to address it. They should, but they're not, and that's sad. That sort of sadness is a common theme with Java.

[kaba0]

While this could be solved by introducing one into the standard lib, it is not that big of a problem in practice as nullability checkers understand all of these annotations.