Jan Ouwens

My ignite session is accepted for #JFall this year! > Designing a Lego model, or how my relaxing hobby turned out to be a software project in disguise This is the story of a two-week project that took me nearly two years to complete. Somehow I will make everything fit in five minutes.

Releasing a blog post and an EqualsVerifier in a single morning...things shoulldn't get any crazier today. Time to get some real work done 😅

EqualsVerifier 4.5.2 is out! It fixes an issue when you have a sealed hierarchy with a singleton enum that comes first alphabetically... Check it out at github.com/jqno/equalsv... #java

I finally managed to get a Chromecast working in a vacation home! jqno.nl/post/2026/08...

EqualsVerifier 4.5.1 is out! It now has a built-in prefab value for LinkedHashSet. As always, check the release notes at github.com/jqno/equalsv... #java

Dear supermarket, why must you torture me so?

That's Thursday! Don't forget to sign up 😉

Want to see the insane talk I wrote about the insane programming language that I built? Join us at the @openvalue.eu meetup next week! www.meetup.com/openvalue/ev...

I went to see Beat the other day: King Crimson veterans playing their 80s songs. At the end of the show it was hard not to agree with Adrian Belew:

I deleted my Twitter, closed my Dropbox account and installed a new OS on my phone: I'm trying to move away from Big Tech jqno.nl/post/2026/05...

EqualsVerifier 4.5 is out! It adds a new check: it fails if you use java.net.URL's equals() method, because this will make a network call that can be flaky. (Convert to java.net.URI instead.) You can suppress this with a new Warning though. Check it out: github.com/jqno/equalsv... #java

EqualsVerifier 4.4.2 is out! It's a bugfix release that improves the layout of error messages, fixes a small bug with Kotlin lazy fields, and fixes two other minor issues. Check it out: github.com/jqno/equalsv... #java

EqualsVerifier 4.4.1 is out. It contains a bug fix for floats and doubles. See also: github.com/jqno/equalsv... #java

EqualsVerifier 4.4 is out! It contains a fix for Java 26's "final means final" warnings. (Yes, I know Java 26 not released yet 😅) Check out the changelog at github.com/jqno/equalsv... and also the updated manual at jqno.nl/equalsverifi... #java

Agreeing with everything! And I also cross my fingers for the teased piece on (or yelling at) JPA, because it sounds like even more I would keep agreeing to 😁

My story on database schemas is published in the (Dutch) Java Magazine! Unfortunately it had to be shortened, so if you want to read the full version (or don't have access to Java Magazine), you can find it on my blog! jqno.nl/post/2026/02...

EqualsVerifier 4.3.1 is out! It respects the Kotlin data class contract as described here: kotlinlang.org/docs/data-cl... As always, check out the changelog: github.com/jqno/equalsv... #java

I just found out that my Lego model of the Tilburg city skyline was put up for sale on AliExpress without my knowledge or consent. I guess that means I'm in the big leagues now!! 😂 (It's cheaper if you go through bricklink.com BTW 😉)

My J-Fall (@nljug.bsky.social) talk is now on YouTube! www.youtube.com/watch?v=4nVc...

EqualsVerifier 4.3 is out! It fixes an issue with consecutive calls to `ScanOption.except()`. Check it out at github.com/jqno/equalsv... #java

EqualsVerifier 4.2.6 is out! 🎇 For sealed types, it can now use all permitted non-abstract subclasses instead of only the first one, which is handy if the first one has a recursion. It also fixes a potential bug for records. As usual, check it out at github.com/jqno/equalsv... #java

EqualsVerifier 4.2.5 is out. It runs slightly faster, and is slightly better factored! Check it out at github.com/jqno/equalsv... #java

Frank interviewed several experts, and me, about sustainability in IT at J-Fall for the @foojay.io podcast. I like how it came out!

I spent 6 hours in MS Teams meetings today. Let's not repeat this any time soon...

EqualsVerifier 4.2.4 is out! Some people reported an UnnecessaryStubbingException caused by EqualsVerifier. This is now fixed! Check out the changelog at github.com/jqno/equalsv... #java

EqualsVerifier 4.2.3 is out! It contains some small improvements for tests that are run on the module path. Also, it improves on error messages when Mockito is in use. Check it out at github.com/jqno/equalsv... #java

EqualsVerifier 4.2.2 is out! It now supports EnumSets and EnumMaps for enums with only one value. Also, I fixed an error message that referred to Warning.ZERO_FIELDS, which was removed in version 4.0. All in all, very exciting stuff Check it out at github.com/jqno/equalsv... #java

Thank you to everyone who joined my talk at #jfall today! You can find my slides here: jqno.nl/talks/slides...

I'll be at #JFall next Thursday! Hope to see you there!

EqualsVerifier 4.2.1 is out! It fixes an issue with Kotlin lazy delegates with a generic type. Check out the changelog at github.com/jqno/equalsv... #java

It turns out the YouTube app on my tv was set to Dutch, and I could change it in the settings. I set it to English which fixes my problem! (And probably introduces the new problem of translating all Dutch videos into English...but we'll cross that bridge when we get there) Thanks @bjeaurn.com !

EqualsVerifier 4.2 is out! It has prefab values for Java 25's ScopedValues, but the main attraction is that support for #Kotlin delegates is greatly improved! They're now much easier to work with, and also error messages are much clearer. Check out the details at github.com/jqno/equalsv... #java

I just upgraded EqualsVerifier and I have to say, the process was extremely painless! I had exactly 1 deprecation to deal with and that was it.

EqualsVerifier 4.1.1 is out! It fixes an issue with classes that extend Enum Check it out: github.com/jqno/equalsv... #java

EqualsVerifier 4.1 is out! It adds the method withResettablePrefabValues, which allows you to have values that are re-inintialized after each check that EqualsVerifier runs internally. Handy for values that mutate when they're used. See github.com/jqno/equalsv... #java

Looks like I'll have to update my blog soon: there's a new player in town 😄

So, here is my new #java side-project: jdtfmt - a Java #formatter for the command line. * Can be paired with #spotless (both use jdt). * fast (native) github.com/bmarwell/jdt... Thanks to @jqno.nl for the inspiration, @mthmulders.bsky.social for #graalvm hints and @bdemers.io for encouraging me 😀

And EqualsVerifier 4.0.9 is out, too! Sometimes you introduce a bug while fixing one... 🤦🏻‍♂️ Check it out at github.com/jqno/equalsv... #java

EqualsVerifier 4.0.8 is out! It fixes an issue with abstract sealed types that add state and need `Warning.NULL_FIELDS` suppressed. Check it out at github.com/jqno/equalsv... #java

Yes let's hide the important stuff, thanks GitHub

Somehow, Microsoft Outlook has found a way to make GitHub notification mails even more annoying than they already were

EqualsVerifier 4.0.7 is out! It fixes a bug with file path separators on Windows when using forPackage() See github.com/jqno/equalsv... #java

EqualsVerifier 4.0.6 is out! JPA entities with lazy fields must use their getters in equals. EqualsVerifier checks this but can't do it if the getter is final. It now throws an error if the getter is final instead of silently skipping the check. Check it out: github.com/jqno/equalsv... #java

I know Kotlin is the cool, hip thing these days, but the mysterious ways it generates bytecode for some of its syntactic sugar features makes my life as EqualsVerifier maintainer pretty difficult in ways that Scala never did

EqualsVerifier 4.0.5 is out! It fixes a regression when testing relaxed equals relations. Check it out at github.com/jqno/equalsv... #java