What we're about

Are you interested in Java or other JVM related programming languages and are you located or often found in or around Rotterdam? Join our JUG.

The goal of the Rotterdam JUG is to harvest the Java community in our area. To connect developers, build connections and to coach and help each other, to grow and share knowledge!

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Upcoming events (1)

Error Prone at Picnic & React at the Port of Rotterdam

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The Rotterdam JUG is back! 🎉

Our host this time is (once again) the amazing Port of Rotterdam.

We have two amazing speakers sharing interesting stories. First we have Mario Klaver, he's going to share the story about how the Port of Rotterdam adopted React to create a new modular front-end for their huge Port Community System called HaMIS.

Next we have (Java Champion) Sander Mak from Picnic, he's going to share how they automatically hunt for errors and bugs using Google's Error Prone.


17:00: Kick-off with food/drinks

18:00: How to develop a large React application without getting messy

React is a powerful and popular front-end framework. But without much guidelines and common practices, a larger application will become a spaghetti code quite quickly. In this presentation, I will tell you our roadtrip in our transition to a modular react application. I present you alternatives for splitting up and maintaining a huge codebase. We will touch on topics like atomic design, state management, feature based development and mono repo.

19:00: Streamlining Large-Scale Java Development Using Error Prone

Using static analysis to spot bugs in your code has become a staple of modern Java development. But what if we can take this one step further where, instead of just finding issues, we fix them automatically? And, what if we can do this not just for bug patterns but for any coding pattern you'd like to enforce?

At Picnic we use Google's Error Prone and Refaster tooling to do just that. In this session you'll learn what these tools are and how to use them effectively. Large-scale refactoring and enforcement of code patterns becomes a breeze once you master these tools. What's more, you'll get a view of some the automated refactorings we use within Picnic at scale. Come and learn how to take control of your codebase like you never have before!

20:00: Networking with some drinks
21:00: Time to go home.

Our guest speakers:

Mario Klaver is a developer at Port of Rotterdam. He has been in the business for over 25 years. Originally a Java developer, his projects always had to have a user interface. These days he feels like a fish in the water in both the frontend world (React/Typescript/CSS) and the backend (Java/Kotlin). Besides that, he develops Android/iOS apps (mostly in React Native). Mario loves to share his knowledge. He regularly speaks at Know-IT (a club with experienced IT colleagues), has spoken at conferences such as J-Spring and XP Days. He also taught students at the HAN in Arnhem.

Sander Mak is part of the tech leadership team at Picnic —the Dutch online grocery scale-up— building Java-based systems at scale. He also is a Java Champion and author of the O'Reilly book Java 9 Modularity (see javamodularity.com). As an avid conference speaker, Sander loves sharing knowledge, also as Pluralsight instructor.


The Port of Rotterdam has graciously offered to host this event in their headquarters. The address is:

Wilhelminakade 909
3072 AP Rotterdam

The best way to get here is using the Rotterdam metro system, a short walk from Wilhelminaplein.

Past events (5)

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