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About us

Java User Group for the northern Dutch provinces with a focus on JVM languages such as Java and Kotlin. We'll be hosting events in both Friesland and Groningen.

We're looking forward to host both experienced speakers as well as aspiring new speakers, so if you have anything interesting to share in the JVM field or regarding engineering culture feel free to reach out!

Some of our sessions will be in English 🇬🇧, some in Dutch 🇳🇱. We'll make sure to mark them!

(mini) Code of Conduct
Be kind and respectful of the other participants and speakers. Participants violating these rules may be sanctioned or expelled from the meetup.

Upcoming events

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  • 7 seats left
    May 2026: last minute - Developer career masterplan workshop

    May 2026: last minute - Developer career masterplan workshop

    ING Hazel, Reviusstraat 2, Leeuwarden, NL

    Join us on Friday, May 1st for another engaging JUG Noord meetup in Leeuwarden, with Bruno Souza from Brazil sharing his insights on growing your career as a software engineer or speaker.

    📅 Date & Time:
    Venue opens: 13:00
    Venue closes: 17:00

    📍 Location: ING Leeuwarden, Hazel: Reviusstraat 2, 8913 HT Leeuwarden

    🚨 Important: Signing up is mandatory for entry. If the name on your Meetup profile does not match your ID, please contact Johan (organizer) with your full name. As there are limited seats: please adjust your RSVP if you're unable to join.

    🇬🇧 Developer career masterplan workshop by Bruno Souza
    Looking for a plan to take your career to senior levels and beyond, and help you reach an outstanding reputation and the best positions in the market?
    From getting the first job to getting the best job, from technology to creating amazing impact in the world, this interactive career conversation will both offer a proven masterplan, but Bruno will also discuss real career issues that you may have.

    Based on the book of the same name by Bruno Souza and Heather VanCura, this presentation will walk you through the most important steps of technical career advancement, and will help you build your personal plan for an expert career.

    Note: our regular meetup with dinner on May 12th will be announced soon.

    About the speaker
    Since 1995, Bruno has been helping Java developers advance their careers and work on exciting projects. A recognized Java Evangelist and Java Champion, as well as a board member of the Java Community Process, Bruno founded and leads SouJava, the Brazilian Java Users Society. In his book, "Developer Career Masterplan," Bruno shares insights on career development for senior developers, topics he further explores in his Code4.life project.

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    3 attendees
  • May 2026: No more NullPointers and graph database modelling in Java

    May 2026: No more NullPointers and graph database modelling in Java

    ING Hazel, Reviusstraat 2, Leeuwarden, NL

    Join us on Tuesday, May 12th for another engaging JUG Noord meetup in Leeuwarden, where Hinse will share how we can prevent nullpointers with JSpecify (included in the latest Spring!) and Paulien will explore how graph databases can help you model complex domains in Java.

    📅 Date & Time:
    Venue opens: 16:30
    First talk starts: 17:00
    Food & drinks: Provided between the sessions

    📍 Location: ING Leeuwarden, Hazel: Reviusstraat 2, 8913 HT Leeuwarden

    🚨 This is the new ING office, a 5 minute walk from the old one so keep that in mind while traveling. For those arriving by car: paid parking is available next door, or at Fonteinland or next to the WTC.🚨

    🚨 Important: Signing up is mandatory for entry. If the name on your Meetup profile does not match your ID, please contact Johan (organizer) with your full name.

    🇬🇧 Never a Null Moment with JSpecify by Hinse ter Schuur (SDB Java)
    Since the beginning of Java we're used to dealing with NullPointerExceptions. We tried to prevent null references using project conventions and sprinkling (a lot of) annotations throughout our codebases. But even with all this tedious work we still run into "null moments", unexpected NullPointerExceptions showing up at runtime.

    One of the reasons this problem has been hard to solve is that Java never had a standard well-defined way to express nullness. Different annotation libraries and tools exist, with slightly different semantics. As a result, annotations often act more as hints than as guarantees. JSpecify aims to change this. It's a collaborative effort by major Java ecosystem stakeholders to define clear, consistent nullness semantics.

    With JSpecify, you can set default nullness per package via the @NullMarked annotation, making your intent explicit. Because of this precision, JSpecify offers a solid foundation to provide null-safety in your libraries and applications. You don’t need to annotate everything or rewrite existing code to get started. In this session you will learn what makes JSpecify different from other attempts. You'll also discover how you can start applying JSpecify incrementally in your own production code right away.

    🇬🇧 Thinking in Relationships: Practical Graph Database Modelling in Java with Neo4J by Paulien van Alst (OpenValue)
    As a Java developer, we are used to thinking about relational databases and occasionally about document stores. But when working with domain models where relationships are first-class citizens and data is highly connected, graph databases are very valuable to consider.

    In this talk, we will explore how graph databases can help you model complex domains with highly connected entities more naturally. Examples of such domain models are criminal investigations, recommendation models, family trees, or HR models.

    Neo4j is a graph database that integrates well in Spring boot applications. Based on my experiences with Neo4j in multiple projects, I’ll walk you through how to model a domain as a graph and introduce you to Neo4j and its query language Cypher. Also, I’ll introduce you to some common pitfalls to avoid when adopting graph databases and what consequences those pitfalls can have. Finally, I’ll show how a re-modelling of a graph saved us from stepping away from Neo4j and helped us understand our domain and its challenges even more. You will walk away with clear knowledge on how and when to start a project with graph databases.

    About the speakers
    Hinse is a Software Engineer at SDB Java. He has been a professional Java coder for over 20 years. He loves to share his experience by doing pair programming, reviews, writing articles and giving talks.

    Paulien is a passionate software engineer in love with readable, reliable, and testable code, independent of the language or technology used. At OpenValue, she works on helping companies set up better software. Lately, she has been giving presentations and workshops about what she encounters during her day-to-day work. In her free time, she likes to sport and to cook, whenever she is not rebuilding her house and garden.

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    5 attendees

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