Hi,
My proposal was centered around compile-time checks and targets mostly
developers and contributors. I am not questioning the usefulness of
runtime checks when these make sense.
Maybe an example is better than a thousand words. Let's imagine a
simple getOrDefault() method. Which version do you prefer?
1. Annotate only nullable items:
public String getOrDefault(@Nullable String s, String def) { return s
== null ? def : Objects.requireNonNull(def); }
2. Annotate only non-null items:
@Nonnull public String getOrDefault(String s, @Nonnull String def) {
return s == null ? def : Objects.requireNonNull(def); }
3. Annotate everything:
@Nonnull public String getOrDefault(@Nullable String s, @Nonnull
String def) { return s == null ? def : Objects.requireNonNull(def); }
Many places in Polaris are using option 3, which is too verbose and
leads to visual fatigue. What I was suggesting to the community is to
adopt option 1, that reduces the visual clutter and also assumes
non-null by default.
(You will notice that I added a runtime check to all three versions.)
Hope that helps to clarify the discussion.
Alex
On Wed, May 21, 2025 at 8:54 PM Yufei Gu <flyrain...@gmail.com> wrote:
>
> >
> > In my opinion, assuming everything is nullable by default isn't the
> > best approach for writing robust code. I believe a bias towards
> > non-nullness leads to more reliable systems.
>
> I agreed with the intention, but am concerned that assuming everything is
> non-nullness may discourage null-checking, which is problematic as runtime
> null-checking isn't a thing.
>
> Yufei
>
>
> On Wed, May 21, 2025 at 9:52 AM Alex Dutra <alex.du...@dremio.com.invalid>
> wrote:
>
> > Hi Eric,
> >
> > You're right that annotations don't change the bytecode at runtime.
> > Their real value comes during compilation, as many static analysis
> > tools use them to flag potential issues. They can even cause build
> > failures depending on how you configure them. My IDE (IntelliJ)
> > frequently warns me when I forget to handle a potential NPE; if you're
> > not seeing similar feedback, it might be worth checking your IDE
> > settings.
> >
> > While the annotations are primarily for compile-time checks, that
> > doesn't mean we can't also incorporate runtime checks. We should aim
> > to include these whenever this makes sense, for example by using
> > Guava's Preconditions. This is especially useful if we can't guarantee
> > that a method parameter, for instance, will never be null, because
> > it's being provided by some external system.
> >
> > In my opinion, assuming everything is nullable by default isn't the
> > best approach for writing robust code. I believe a bias towards
> > non-nullness leads to more reliable systems.
> >
> > I am also a big fan of Optional and think we should strive to use it
> > as much as possible. That said, it's not always possible, especially
> > if you are implementing a third-party interface that doesn't use it.
> > Using Optional in class fields and method parameters is also
> > controversial: Optional was designed primarily as a signal from the
> > callee to the caller, to signify: "no result". In other words, its
> > main purpose is to clarify method return types. This post on Stack
> > Overflow by Brian Goetz is worth reading: [1].
> >
> > Thanks,
> >
> > Alex
> >
> > [1]:
> > https://stackoverflow.com/questions/26327957/should-java-8-getters-return-optional-type/26328555#26328555
> >
> >
> > On Wed, May 21, 2025 at 4:37 PM Eric Maynard <eric.w.mayn...@gmail.com>
> > wrote:
> > >
> > > Thanks for bringing this up as I’ve been confused by this a few times.
> > >
> > > Before Polaris I hadn’t really encountered these annotations and I was
> > > surprised to learn they don’t “do anything” — that is, there is no
> > > additional safety you get at runtime when a null value is passed into a
> > > parameter marked non-null. Similarly nothing enforces that you handle
> > null
> > > values when something is annotated as nullable.
> > >
> > > For that reason, I tend to assume everything is nullable regardless of
> > > annotation and I would be in favor of standardizing around that
> > assumption.
> > > Iff something is annotated as Non-null a developer should feel safe
> > > skipping a check for null, but otherwise they should handle null.
> > >
> > > I am a big fan of Optional and of trying to reduce the usage of null as
> > > much as possible though.
> > >
> > > On Wed, May 21, 2025 at 3:02 PM Alex Dutra <alex.du...@dremio.com.invalid
> > >
> > > wrote:
> > >
> > > > Hi all,
> > > >
> > > > A while ago, we had a discussion regarding which nullness annotations
> > > > to use and whether we should consider favoring non-null by default. I
> > > > would like to revive that discussion.
> > > >
> > > > We are currently using the `jakarta.annotation` package consistently,
> > > > but the defaults are not clear: should we consider everything as
> > > > non-null by default and only annotate the nullable things, or the
> > > > other way around? Some classes are cluttered with both annotations,
> > > > which seems unnecessary and confusing.
> > > >
> > > > I would personally be in favor of considering everything as non-null by
> > > > default.
> > > >
> > > > Please let me know your thoughts.
> > > >
> > > > Alex
> > > >
> >
