December 2021 - Barry Evans

Local Java developer and DubJUG Co-Lead, Barry Evans, will present DubJUG's first in-person event (since March 2020) on the evening of December 21st!


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Additional Information

Session Abstract

19:00 - Eclipse Collections Kata 2.0

After a three-year hiatus (can you believe it's been that long) our very own Barry Evans is back once again, leading a Kata session with the only Java collections library worth talking about today!

Come and join Barry and the rest of your fellow DubJUG'ers for some festive-fun-filled-frolics, by completing a code kata using the eclipse collections; hopefully, there will be plenty of Santa hat wearers in attendance to mark the jolly occasion.

A kata is an exercise in martial arts. A code kata is an exercise in programming which helps hone your skills through practice and repetition. But what's that I hear you say "eclipse collections, again?"... well, not quite.

In the past three years, there have been a number of important updates to the eclipse collections library and its Katas, including:

Two new releases (v10 and v11) A wide range of optimisations, several new community-requested features, and lots of tech debt removed (we all hate tech debt, right)

Support for up to JDK 15

Four new Katas, including a Candy Kata so you can learn more about the awesome Bag data structure.

In this tutorial session, the audience will learn Eclipse Collections by going through the Eclipse Collections Kata. This kata is set up as a series of unit tests that fail. The participants will make the tests pass using Eclipse Collections. The instructor will discuss the solutions live and explain the concepts behind the various patterns in greater detail.

Common iteration patterns, basic collection types, Primitive collections, and basic refactoring techniques will be covered in the tutorial.

What you will need to build the katas:

  1. JDK 11

  2. Maven 3.6.1+

  3. IDE of your choice that has support for JDK 11

  4. Your laptop!

About Eclipse Collections

Eclipse Collections (formerly known as GS Collections) is an open-source Java collections framework that supplements JDK collections. It was migrated to Eclipse foundation in October 2015. Eclipse collections has both object and primitive containers; rich APIs available for eager and lazy iteration patterns; mutable and immutable collections; and additional container types not available in the JDK, such as Bag and Multimap.

For more information on Eclipse Collections visit:

Eclipse Collections is the best Java collections framework ever that brings happiness to your Java development.

Why Eclipse Collections?

  • Productivity

    • Rich, functional, and fluent APIs with great symmetry
    • List, Set, Bag, Stack, Map, Multimap, BiMap, Interval Types
    • Readable, Mutable, and Immutable Types
    • Mutable and Immutable Collection Factories
    • Adapters and Utility classes for JCF Types
  • Performance

    • Memory Efficient Containers
    • Optimized Eager, Lazy and Parallel APIs
    • Primitive Collections for all primitive types

About Barry

Barry is a seasoned web application engineer with over fifteen years of experience developing enterprise applications in the financial and other sectors.

Presently, he is an Oracle Certified Senior Fullstack Software Engineer at Fidelity Investments Ireland, and, we hear, a pretty smooth mover on the dancefloor ….. 'you asking?'

Find him on Twitter @bazza_ni

About the Oracle Dublin Java User Group

The Oracle Dublin Java User Group, aka DubJUG, is Ireland's oldest JUG serving Java developers in Ireland. Since 2006, the Group has been bringing Java Champions, Java One Rock Stars, and Duke Award winners to Dublin for the benefit of our community of Java software professionals. Oracle is the current Headline Partner.

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