Core Java on JAVAPRO International

From ‘Class Not Found’ to Calm: Practical Shading and Shadowing for Java Apps

Tue, 07 Jul 2026 07:07:12 +0000

Your pipeline is green, the app is deployed, and everything looks fine… until production says “nope”. A request fails and the logs show ClassNotFoundException, or worse, NoSuchMethodError. These are among the most confusing runtime errors because the code compiled successfully, but the JVM is acting differently than you would expect.

Let’s dive in and explore how the class loader works, what class shadowing is (when one class silently wins over another on the classpath) and what class shading is (when you deliberately relocate packages so multiple versions can coexist). We’ll also see how these two concepts can help solve mysterious production issues and make your app more stable and secure.

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Tue, 30 Jun 2026 08:50:00 +0000

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Download free PDF here: Edition 06/2026 | Autonomous Java

06-2026 | Autonomous Java

Tue, 30 Jun 2026 07:00:02 +0000

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CORE JAVA
▪️Learning Java Automation the SOLID Way: A Beginner’s Guide to Learn Page Object Model with Java SOLID Principles
▪️OpenJ9 GC Policies: How to Choose the Right Collector

API & FRAMEWORKS
▪️Elasticsearch Java SDK: No Magic, Just Solid Design Choices
▪️Java Developers, You’re Already Ready for Blockchain — You Just Don’t Know It Yet
▪️Connecting Java Reinforcement Learning to Python Gymnasium
▪️Beyond Text Search: A Smarter Way to Understand Your Code
▪️The 3 A.M. Deadlock

The Foundations of Data-Oriented Programming in Java

Wed, 24 Jun 2026 07:00:01 +0000

Introduction

Java has traditionally been an object-oriented language, urging developers to structure code around objects, encapsulate state and behavior, hide implementation details, and extend functionality through inheritance. This method has advanced modularity and reusability. However, with recent enhancements, Java has evolved, revolutionizing how systems are developed and offering powerful tools for developers.

Have you ever been in the midst of debugging a complex Java application, only to find that the mutable state across various objects left you tangled in a web of unexpected behaviors and racing conditions? These frustrations are common among Java developers accustomed to Object-Oriented Programming (OOP), where mutable objects often lead to more complex, less predictable systems. Fortunately, with recent language enhancements, Java developers now have capable tools to treat data as a first-class citizen.

1BRC - The First 80% of the Journey

Tue, 23 Jun 2026 07:00:02 +0000

The One Billion Row Challenge (1BRC) started as a way to kill time during the 2023/2024 holidays, asking a simple question: How fast can Java crunch temperature values from a text file and calculate the min, mean, and max per weather station? The catch is that the file contains one billion rows, totaling approximately 13.8 GB.

Thomas Wuerthinger, Quan Anh Mai, and Alfonso Peterssen achieved the best result of 1.5 seconds on 8 cores. That was insanely and unexpectedly fast. But when you take a closer look at the code, you will see that it is beyond your daily dose of Java. It is a complex, single-use-case-oriented implementation, skipping safety features, and most of the tunings applied cannot be easily reused.

Structured Concurrency in Java 26 (JEP 525 Deep Dive)

Tue, 09 Jun 2026 07:00:01 +0000

The Java 26 Evolution of Safer, Predictable Multi-threading

Java has long provided powerful concurrency primitives. Threads, executors, futures, and more recently virtual threads allow applications to scale across cores and I/O boundaries. Yet many production failures are not caused by insufficient parallelism, but by insufficient structure.

Tasks outlive the operations that spawned them. Failures are detected but not propagated consistently. Interrupts are delivered but not observed in time. Thread dumps reveal activity, but not ownership or intent.

JCON EUROPE 2026: Why the Java Community Still Meets in Person

Mon, 01 Jun 2026 07:00:00 +0000

Every year, when we start planning JCON EUROPE, one question always guides us:

How do we create a conference that developers genuinely enjoy attending?

Not just another event with slides and sponsor booths. Not a place where people passively consume information and leave. We wanted to create an environment where developers actively connect, discuss, challenge ideas, and solve real-world problems together.

Looking back at JCON EUROPE 2026, I believe this spirit was visible everywhere.

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Thu, 28 May 2026 12:00:00 +0000

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‘From AI as a Feature to AI as Infrastructure’ – download free PDF here!

05-2026 | From AI as a Feature to AI as Infrastructure

Thu, 28 May 2026 10:41:04 +0000

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JCON
▪️JCON Europe 2026: Why the Java Community Still Meets in Person

CORE JAVA
▪️Java 26 Is Boring
▪️Structured Concurrency in Java 26 (JEP 525 Deep Dive)
▪️Are the Classic Design Patterns Still Valid with Modern Java?

API & FRAMEWORKS
▪️The Gen AI Iceberg – Java Tooling Edition
▪️Building AI-Driven Java Systems with Spring AI and Java 26
▪️LangChain4j Agentic Workflows: From AI Calls to Multi-Agent Systems in Java

OpenFeature - one flag to rule them all!

Thu, 14 May 2026 07:00:01 +0000

Feature flags and where to find them

What are feature flags?

To keep it simple it’s a way to change the system behaviour at runtime without hassle.

Note: And if this “refresher” was the only theoretical thing you wanted to know or if you already use feature flags and want to jump straight to code/ OpenFeature demo, feel free to do so; otherwise, please bear with me for another couple of text pages.

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Tue, 28 Apr 2026 12:00:02 +0000

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Download free PDF here: Edition 04/2026 | Java in the Age of AI

04-2026 | Java in the Age of AI - Special Edition

Mon, 27 Apr 2026 12:50:36 +0000

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JCON
▪️A Big Screen Experience for Java Developers & Architects

CORE JAVA
▪️A Big Screen Experience for Java Developers & Architects
▪️Effective Pattern Matching 2026 Edition
▪️Data Oriented Programming with Java
▪️Java 26 adopts HTTP/3 with the Evolution of the HttpClient
▪️Java 26 GC: Making Data Streaming Faster and More Reliable in Containers
▪️1BRC – The First 80%
▪️Building GPU Accelerated LLM Inference Libraries with TornadoVM
▪️Reactor Has Died, Long Live REACTOR!

Don’t Miss: New AI Award & AI Highlights at JCON 2026

Mon, 20 Apr 2026 13:08:00 +0000

JCON EUROPE 2026 is about to kick off – and anticipation is building. The conference opens its doors today in Cologne, once again bringing together the international Java community. Just ahead of the event, new high-profile AI highlights have been announced, making it one of the most important meeting points for AI and Java experts in Europe.

Focus on AI: Highlights on Wednesday

A special focus is placed on AI on Wednesday, April 22. The day begins with a high-level keynote:

Java Vector API: Faster vector computations for the JVM

Thu, 09 Apr 2026 07:00:02 +0000

Introduction

Modern CPUs contain vector registers. These vector registers hold multiple numerical values as the same time. They enable SIMD (Single Instruction Multiple Data) which allows same instruction to be applied to multiple pairs of data which is present in these vector registers. SIMD is a natural choice for parallel data processing which is needed for processing arrays, large binary files, statistical analysis etc.

Historically, Java developers relied on the HotSpot compiler to auto-vectorize simple loops. Auto-vectorization is an extremely fast choice when it applies, but it requires a lot of conditions to be met to be applied: many real-world loops are not transformed because the compiler cannot prove safety or profitability. Java’s Vector API was introduced to close this gap by providing a clear, explicit, platform-agnostic way to express vector computations so that they can be reliably compiled to the best available hardware instructions and still run correctly (with “graceful degradation”) when vector instructions are not available or not applicable.

Caching and Beyond: Smarter Data Processing with Java - in 2 Hours

Thu, 02 Apr 2026 11:45:01 +0000

Many Java teams start simple — a single database, a straightforward architecture. But as systems evolve, so does the stack: caching layers to improve performance, search engines for faster queries, additional databases for specialized use cases, and now vector stores for AI-driven features.

What begins as optimization often turns into a fragmented landscape of technologies. The result: increasing complexity, higher infrastructure costs, and growing DevOps overhead.

The session “Caching and Beyond – Smarter Data Processing with Java” at JCON EUROPE takes a different approach. Instead of adding more tools, it focuses on simplifying data architectures — using a clean, Java-centric model built on open-source technologies.

The Inconvenient Truth About Code, 30 Years of Java & Sovereign AI – The Keynotes of #JCON2026

Fri, 27 Mar 2026 07:00:01 +0000

4 Days | 100+ Speakers | 100+ Sessions | In-Person

JCON EUROPE 2026 is just around the corner and once again brings the international Java community to Cologne. At the Cinedom Cinema, attendees can expect an extensive program with over 100 sessions as well as three central keynotes that will open each conference day.

Three Keynotes at a Glance

Java: 30 Years and Beyond

Tuesday, April 21 | 10:15 AM | Cinema 5
Speaker: Sharat Chander (Senior Director & Head of Global Devleoper Programs, Oracle)

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Thu, 26 Mar 2026 12:05:02 +0000

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‘From Coder To System Designer’ – download free PDF here!

03-2026 | From Coder to System Designer

Thu, 26 Mar 2026 11:50:02 +0000

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JCON
▪️Architect Your Own Experience: Creating Your Individual JCON 2026 Journey

CORE JAVA
▪️The Foundations of Data-Oriented Programming in Java
▪️Lazy Constants in Java 26: Deferred Immutability and JVM Trust
▪️Final Is No Longer a Hint in Java 26
▪️Java 26 in Practice: How the JVM Is Changing the Way We Write Code
▪️Reverse Engineering Java: Backtracking Native Crashes

API & FRAMEWORKS
▪️Paketo Buildpacks: Ready for Java 26 & More!
▪️Stop Writing YAML: How to Define, Test, and Deploy Your Cloud in Pure Java
▪️Beyond REST: Rethinking APIs with GraphQL and Java
▪️Solving Spring AI’s UI Challenge with AG-UI’s Java SDK

More Than Just a Conference for Java Enthusiasts | JCON 2026

Tue, 24 Mar 2026 12:00:02 +0000

With over 100 speakers, more than 100 sessions, and a diverse supporting program, JCON Europe 2026 once again positions itself as one of the leading events for the Java community. Taking place in Cologne as an in-person conference, the event combines deep technical expertise with a strong focus on creating a highly customizable attendee experience.

A Conference Tailored to You

JCON Europe 2026 is designed to give participants full control over their conference journey. A wide variety of session formats, thematic tracks, and networking opportunities allow developers to build a schedule that aligns with their interests, experience level, and career goals.

How JCON Becomes Your Individual Highlight!

Tue, 03 Mar 2026 12:31:42 +0000

After welcoming attendees from 56 countries across six continents at JCON EUROPE 2025, JCON is aiming to surpass last year’s success and reach new heights.

Live Coding Experience on the Big Screen - unique in Germany

Developers want to see code. For this reason, the 11th edition of JCON will once again take place as an in-person conference in a multiplex cinema in Cologne. The event transforms coding and programming into a cinematic spectacle, ensuring that every detail of the incredible speakers is showcased in full detail on the big screen.

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Mon, 23 Feb 2026 12:20:13 +0000

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Download free PDF here: Edition 02/2026 | Engineering Intelligence - Building Systems in the AI Age

02-2026 | Engineering Intelligence

Mon, 23 Feb 2026 11:07:31 +0000

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JCON
▪️Engineering Intelligence Live: JAVAPRO Benefits for JCON 2026

CORE JAVA
▪️Building Low-Latency Event Pipelines With Java 25
▪️Achieving Microsecond Latencies With Java: Practical Techniques for Building Ultra-Fast Systems

API & FRAMEWORKS
▪️API Development: Implementing POST and SSE Events in Jakarta REST
▪️Open J Proxy: A Modern Open-Source Approach to Database Connectivity for the Java Ecosystem
▪️From Tables to JSON: Handling Unstructured Data in RDBMS Systems With Spring Boot
▪️Java 26 and Spring Boot 4: From Certification Skills to Production-Ready Applications
▪️From Cron to Carbon and Cost-Aware: Modernizing Java Background Jobs
▪️Why Struts 1.3 Still Matters in 2026
▪️The Jakarta Cliff: Why Modern Java Leaves Struts 1 Behind

Free Tickets for JCON EUROPE 2026

Wed, 11 Feb 2026 12:00:00 +0000

4 Days | 100+ Speaker | 100+ Sessions | In-Person

The Ultimate Java Experience on The Big Screen!

JCON EUROPE 2026 is returning to the big cinema screen from April 20–23, 2026! Join JCON for a top-tier Java conference featuring four parallel tracks, hands-on workshops, and a vibrant international Java community.

📅 Monday, April 20th – Big Workshop Day
📅 Main Conference: April 21st- 23rd – Deep-dive sessions, live coding & networking
📅 Premium AI Track: April 21st - 22nd - Special AI-focused track for VIPs & ticket upgrades
📅 VIP Event: April 22nd – Exclusive gathering with Java experts
🍻 Happy Hour: April 21st - 22nd – Unwind and network with fellow developers

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Tue, 03 Feb 2026 11:54:17 +0000

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‘Agentic AI Meets Java’ – download free PDF here!

20% Early Bird Ends January 31 — Premium AI Track and 100+ Sessions Await at JCON 2026

Tue, 27 Jan 2026 12:00:02 +0000

With JCON EUROPE 2026 coming up this spring, the discounted Early Bird phase is about to close. The Early Bird ticket offer ends on January 31, 2026 (23:59, Europe/Berlin) — giving attendees roughly one week to secure the reduced rate before regular pricing takes over.

JCON EUROPE 2026 will take place April 20–23, 2026 at Cinedom Cologne, featuring four in-person days of Java content on an unusual but fitting venue: a cinema. Sessions and demos are designed for the big screen, with the program running daily 9:00–18:00 onsite.

Always Up to Date - with Every New Free PDF Edition!

Tue, 09 Dec 2025 10:37:19 +0000

Have You Enjoyed the Previous Part of Our Special Edition ‘Java 25’?
Now Part 2 is here — and it’s packed with even more expert insights, community voices, and Java highlights from the past 30 years & the Java 25 release.

JCON EUROPE 2026 - CFP 3 Days left

Wed, 22 Oct 2025 13:24:30 +0000

The Call for Papers for JCON EUROPE 2026 is closing soon, with only three days remaining for submissions. The deadline is Friday, October 24, 2025, at 23:59 (UTC+2).

As the premier in-person Java community conference in Germany, JCON EUROPE will return to the Cinedom in Cologne from April 20–23, 2026, bringing together Java developers, architects, and technology experts from around the world.

The conference is renowned for its distinctive cinema setting, strong community spirit, and high-caliber technical sessions. Attendees can look forward to a packed agenda, a vibrant hallway track, and the popular Mentorship Hub hosted by Bruno Souza, offering direct interaction between newcomers and seasoned industry leaders.

Call for Papers for JCON EUROPE 2026 Extended Until October 24

Mon, 13 Oct 2025 17:54:40 +0000

The Call for Papers (CFP) for JCON EUROPE 2026 has been extended by two weeks. The new deadline for submissions is Friday, October 24, 2025 (23:59 UTC+2).

The extension gives potential speakers more time to finalize their proposals for the next edition of Europe’s leading community-driven Java conference. JCON EUROPE will take place April 20–23, 2026, once again at the Cinedom in Cologne – a venue known for its cinema-sized screens and vibrant hallway track atmosphere.

Always Up to Date - with Every New Free PDF Edition!

Tue, 30 Sep 2025 12:24:30 +0000

Have You Enjoyed the Previous Parts of Our Special Edition ‘30 Years of Java’?
Now Part 3 2|2 is here — and it’s packed with even more expert insights, community voices, and Java highlights from the past 30 years.

JCON EUROPE 2026 - CFP Is Open

Tue, 23 Sep 2025 12:00:02 +0000

The Call for Papers is now open, and we’re looking for all to share your expertise, showcase cutting-edge solutions, and inspire the community. Got an exciting project? A story to tell? Real-world insights? We want to hear from you!

Be a pioneer: Help shape the future of Java! Present your innovative ideas and projects to an international audience on a giant cinema screen.
Increase your visibility: Position yourself as a recognized authority in the Java community and take advantage of the opportunity for personal 1-on1 Sessions.
Expand your network: Make contacts with leading experts from the Java world and keep your finger on the pulse.
Experience an unforgettable atmosphere: JCON is more than just a conference - it is a celebration of the Java community.

Your Topics

Whether you are interested in Core Java, cloud-native development, microservices, artificial intelligence or other exciting areas - JCON offers a stage for all aspects of the Java world.

Goodbye to ORM Pain: EclipseStore Hands-On with the Lead of the Open-Source Project

Thu, 24 Apr 2025 12:19:17 +0000

Many Java developers are all too familiar with the downsides of traditional ORM frameworks: performance bottlenecks under scale, complex serialization, and recurring issues when refactoring persistent object models. If you’re looking for a modern, high-performance alternative, EclipseStore deserves a closer look – and not just in theory, but in practice.

Experience EclipseStore in Action – Led by a Core Contributor

At this year’s JCON EUROPE 2025, you’ll have a unique opportunity to get hands-on with EclipseStore. Florian Habermann, CTO of MicroStream Software and a core contributor to EclipseStore, is hosting a two-hour practical workshop. Rather than sitting through slides, participants will actively code – in their own IDEs, with Java, and against production-relevant use cases.

High-Demand Workshops at JCON EUROPE 2025 – Tickets Available Now

Thu, 10 Apr 2025 07:00:03 +0000

Cologne – JCON EUROPE returns to its venue from May 12–15, once again offering an extensive program for Java enthusiasts. In addition to over 100 speakers and sessions, Monday, May 12 is fully dedicated to hands-on, expert-led workshops.

Each workshop is a two-hour deep dive into cutting-edge technologies and real-world development topics. Participants can choose from a total of seven different sessions across two time slots: 1:00–3:00 PM and 4:00–6:00 PM. A coffee break in between provides room for informal networking.

JCON EUROPE 2025: Live Coding, Networking & Community-Highlights

Tue, 08 Apr 2025 10:00:01 +0000

4 Days | 100+ Speaker | 100+ Sessions | 9 Workshops | In-Person

JCON EUROPE 2025 returns as one of the leading Java community events in Europe. Last year’s edition welcomed participants from 56 countries across six continents. The 10th edition will not only feature a packed schedule of technical sessions and live coding formats, but will also place a stronger emphasis on personal exchange and community interaction. Several curated networking formats will complement the conference program, offering attendees direct access to speakers, experts, and peers.

JCON EUROPE 2025 - CFP Is Open

Fri, 18 Oct 2024 21:43:36 +0000

Be a pioneer: Help shape the future of Java! Present your innovative ideas and projects to an international audience on a giant cinema screen.
Increase your visibility: Position yourself as a recognized authority in the Java community and take advantage of the opportunity for personal 1-on1 Sessions.
Expand your network: Make contacts with leading experts from the Java world and keep your finger on the pulse.
Experience an unforgettable atmosphere: JCON is more than just a conference - it is a celebration of the Java community.

Your Topics

Whether you are interested in Core Java, cloud-native development, microservices, artificial intelligence or other exciting areas - JCON offers a stage for all aspects of the Java world.

Save The Date - JCON EUROPE 2025

Fri, 18 Oct 2024 19:03:32 +0000

4 Days | 100+ Speakers | 100+ Sessions | daily 9am - 18pm live |

May 19-22 | Join us in Cologne, Germany for 3 days of Java-powered excitement and a workshop day on Monday. We’ll take over our beloved Cinedom the multiplex cinema in Cologne, Germany and end with a massive birthday bash on Thursday, May 22nd to honor Java’s incredible 30-year journey.

Why JCON EUROPE

This isn’t just a conference; it’s the premiere Java community conference in Germany, where Java developers from around the globe come together. Powered by the Java community and organized by the JAVAPRO Magazin in collaboration with Java User Group Oberpfalz, JCON EUROPE is where brilliant minds come together to learn, network, and have a blast. And this year, with 30 years of Java and the 10th edition of JCON to celebrate, it’s going to be the biggest, most unforgettable edition yet.