Java Annotated Monthly – September 2026

This month’s Java Annotated Monthly brings you the latest Java news, a generous dose of AI-focused articles, Kotlin updates, and highlights from a variety of technologies and frameworks, plus plenty more worth adding to your reading list.

Our featured writer, Aicha Laafia, takes a closer look at upcoming JEPs and shares her key findings on what may be next for Java. Let’s dive in!

Featured Content

Aicha Laafia

Aicha Laafia is a Java software engineer at SQLI with a love for coding, an interest in sustainability, and a commitment to empowering women in tech. She is a Women Techmakers ambassador, an Oracle ACE Associate, and part of the JetBrains Community Contributors program. When she is not coding, she enjoys exploring delicious food, phone photography, and watching Formula 1.

September is here, and so is JDK 27. Nine JEPs if you count the previews, and nothing to rewrite unless you are using preview features. Honestly? That’s my favorite kind of release. You upgrade the version, and your app gets faster.

The features that change your numbers

Compact object headers are on by default (JEP 534). Headers shrink from 96 bits to 64, cutting heap usage by 10% – 20% and pushing throughput up by 5% – 10%. G1 also becomes the default garbage collector everywhere (JEP 523), even on the small machines that used to get Serial GC instead, so check your smallest containers before you upgrade. For the full tour, Sven Woltmann wrote a solid Java 27 breakdown, and if video is more your thing, Catherine Edelveis covers the whole release here.

Still on Java 8 or 11?

Don’t jump, hop. Start now, LTS by LTS, and read my article Jurassic JDK: Migrate or Extinct first. I covered everything I wish someone had told me before my first migration.

Enjoy this month’s Java Annotated Monthly!

Java News

See what’s new, changing, and coming next in the world of Java:

Java News Roundup 1, 2, 3, 4

Project Valhalla’s First Preview: JEP 401 Redefines == for Java Objects

JEP 540 Proposed to Target JDK 28 with a Simple JSON API

JSON API, Valhalla Progress, LTS ❤️ PQC – Inside Java Newscast #114

Inside Java Episode 67 “Keeping Up With the Java Release Train” [I/O]

JDK 27 and JDK 28: What We Know So Far

Announcing Oracle Jipher 10.37: FIPS 140-3 Cryptography for Java

Evolving a Java MCP Server During MCP Specification Upgrades

Java Tutorials and Tips

Sharpen your Java skills with practical tutorials, clever techniques, and tips worth trying:

Persistence Workflows with IntelliJ IDEA – Andrey Belyaev | IntelliJ IDEA Tech Talks

Resilient Sync: Your IDE Keeps Helping even when your Build is Broken

Inside Java Episode 65 “Embracing Virtual Threads with Helidon” [I/O]

Introduction to Retrieval-Augmented Generation with Java and MongoDB

The Power of JDK Flight Recorder: Efficient Profiling and Troubleshooting for Java Applications

Security Baked Into the JVM: sixteen Subjects on the wire

Value Classes Still Need Compiler Sympathy

Inside Java Episode 68 “Operator Overloading with Type Classes” [AtA]

Why is Arrays.fill 265 times slower on G1GC?

Beyond Virtual Threads: Structured Concurrency – Balkrishna Rawool | IntelliJ IDEA Tech Talks

Kotlin Corner

Step into Kotlin Corner for fresh updates:

When Escape Routes Become Toll Roads: Mapping How Developers Move Between Programming Languages

KotlinLLM is Going Open Source

Introducing the Kotlin Benchmark for AI Coding Agents

AI

Catch up on the AI ideas, tools, and experiments shaping how developers build software:

IntelliJ IDEA Goes LSP: Java and Kotlin Intelligence Comes to VS Code, Cursor, and Agentic Flows

JetBrains Details its First Steps to Bring Rapidly Growing AI Spend under Control

Jakarta Agentic AI Hits Its First Milestone

MCP Goes Stateless, and Developers Ask Whether That Just Makes it an API Again

Top 5 AI Features in IntelliJ IDEA

Agent Skills in IntelliJ IDEA

Lessons Learned from Fixing Flaky Tests with Claude

The reality of AI in the enterprise

How to Use AI Agents in IntelliJ IDEA With ACP

Java Enterprise Is Already Ready for the AI Era

Spring Office Hours Podcast: S5E20 – The Developer’s Guide to AI with Danny Thompson

How to accelerate agentic adoption

Languages, Frameworks, Libraries, and Technologies

Explore what’s moving and shaking across languages, frameworks, libraries, and the wider tech landscape:

This Week in Spring 1, 2, 3, 4

Pods as Workers, Not Agents: Rethinking the Deployment Unit for AI Agents on Kubernetes

Gradle Is Going Agentic

When @Immutable Made All the Difference: A 3.2x Speedup with Hibernate Second-Level Cache

Vibe Coding, Maven, and the Dependencies You Didn’t Choose

Conferences and Events

Mark your calendar with the conferences, meetups, and events worth showing up for:

Kansas City Developer Conference – Kansas City, USA, September 9–12

JCConfTaiwan – Taipei, Taiwan, September 11

Java Forum Nord – Hannover, Germany, September 22

JUG Saxony Day – Radebeul, Germany, September 25

Confitura – Warsaw, Poland, September 25–26

GOTO Copenhagen – Copenhagen, Denmark, September 28 – October 2

Culture and Community

Check out these stories about what makes the developer community tick.

The Five Stages of AI Maturity in Engineering Organizations – Where and Why Teams Get Stuck

From Projects to Products: Turning Platforms into Products People Use

When Escape Routes Become Toll Roads: Mapping How Developers Move Between Programming Languages

Culture & Methods Trends 2026: The Human Side of AI Engineering

More Incidents Don’t Necessarily Mean Less Reliability

What Is Reasoning

How Code in the Age of Artificial Intelligence Becomes Write-Only and Disposable

The Human Edge: Why Brownfield Codebases Need Mob Programming, Not Just AI Vibes

Fast and Hard Code

And Finally…

Check out the latest articles by the IntelliJ IDEA team:

The Grails Plugin Has a New Home: Apache Grails

Println Debugging Done Right

Spring Boot Configuration Management Best Practices

Project Loom in IntelliJ IDEA: Virtual Threads, Scoped Values, and Structured Concurrency

That’s it for today! We’re always collecting ideas for the next Java Annotated Monthly – send us your suggestions via email or X by September 20. Remember to check out our archive of past JAM issues for any articles you might have missed!