Sequenced Collections, targeted for JDK 21, are a new collection type created to represent a sequence of elements with a defined encounter order.
Ana recorded this episode with Stuart Marks, the owner of JEP 431 about Sequenced Collections. Stuart discusses the essence of Sequenced Collection interfaces, what needs those address and how they fit within the existing Collections framework. He explains the design of Sequenced Collections, architectural decisions and particularities of the API. He also shares his view on how Sequenced Collections can inspire future Java platform developments.
JDK 28's adaptive heap sizing for ZGC dynamically balances CPU use and memory consumption with close-to-zero configuration. Value classes introduce new challenges for conversions between custom numeric types, which type classes could eventually address, but unresolved questions about how these features should interact mean that primitive patterns won't return in JDK 28 and will instead be withdrawn. 😟 Other highlights are upcoming Java events and JDK 28's planned features.
Links:
Adaptive heap sizing for ZGC:
JEP 546 - Adaptive Heap Sizing for ZGC: https://openjdk.org/jeps/546 Java events:
FOSDEM: https://wiki.debian.org/Java/DevJam/2027/Fosdem JVMLS: https://openjdk.org/projects/mlvm/jvmlangsummit/ JavaOne tickets: https://www.oracle.com/javaone/register/ Value classes, numeric conversions, primitive patterns:
JLS on conversions: https://docs.oracle.com/en/java/javase/27/docs/specs/jls/jls-5.html Brian Goetz on type classes: https://www.youtube.com/watch?v=Gz7Or9C0TpM Amber mail on primitive patterns: https://mail.openjdk.org/archives/list/amber-spec-experts@openjdk.org/thread/UYEK3PGOHN6R56AHJTSLPGAY363K666S/ Amber mail on constant patterns: https://mail.openjdk.org/pipermail/amber-spec-experts/2026-January/004306.html JDK 28:
early-access builds: https://jdk.java.net/28/ feature list: http://openjdk.org/projects/jdk/28/
This episode of the Inside Java Podcast is the Ask the Architect session from Devoxx Belgium 2026, where the audience members literally asked the Java architects their questions. They inquired about custom virtual thread schedulers, AI's impact on the development of Java itself, Valhalla features, string templates, better modules, and more.
Object-Oriented Programming offers a lot of flexibility for modelling diverse domains but not all elements need that flexibility. Data, specifically, is often better modeled by simple, immutable types and while OOP does not prevent that, it can make it a bit cumbersome. So in recent and coming years, Java has gained and will gain a number of features that improve the situation: From flexible constructor bodies to records and value classes, from withers to lazy constants, and more - they all stand on their own, but they also come together to allow us to more expressively and elegantly define, construct, copy, and access immutable data.
In this "Ask the Architects" episode of the Inside Java Podcast, recorded during JavaOne 2026, Nicolai Parlog talks to Dan Smith, contributor to projects Amber and Valhalla and Senior Java Platform Developer at Oracle.
Show Notes:
Better Tools for Immutable Data: https://www.youtube.com/watch?v=BdLND9D81lI JEP 513: Flexible Constructor Bodies: https://openjdk.org/jeps/513 JEP 401: Value Objects (Preview): https://openjdk.org/jeps/401 JEP 468: Derived Record Creation (Preview): https://openjdk.org/jeps/468 JEP 547: Lazy Constants (Fourth Preview): https://openjdk.org/jeps/547
On August 18th, 2026 a mail pops up on the hotspot-compiler-dev mailing list and it describes something that is not supposed to happen: a serious new bug in a JDK release candidate phase, just a few weeks before general availability. Apparently, under very specific circumstances, some buffer contents aren't correctly copied and strings can get corrupted. This is bad, very bad even, and obviously requires analysis and a fix. This is the story of the structure and community that fixes bugs like these and how they operate. We also take a quick look at JavaOne, the Inside Java Podcast, and JDK 28, which is shaping up to be a big release.
Links:
A critical bug:
JEP 3: https://openjdk.org/jeps/3 the original issue: https://bugs.openjdk.org/browse/JDK-8373591 the original PR: https://github.com/openjdk/jdk/pull/28789 Lorenzo's bug description: https://mail.openjdk.org/archives/list/hotspot-compiler-dev@openjdk.org/thread/5NVKBE3C5T5ULKVO5T3RTUQZDIXQMHBE/ Chris' alarm for the P1 bug: https://mail.openjdk.org/archives/list/jdk-dev@openjdk.org/thread/EPJNIMIAROC2QELIZE5MAGU4D6S3FEVG/#K52LJL4HZJE565UBU465PT4ZBRC2XV4Y the bug in JDK 27: https://bugs.openjdk.org/browse/JDK-8390546 backing out the change on the mail branch: https://bugs.openjdk.org/browse/JDK-8390590 backporting the backout to JDK 27: https://bugs.openjdk.org/browse/JDK-8390663 Mark's confirmation: https://mail.openjdk.org/archives/list/jdk-dev@openjdk.org/message/K52LJL4HZJE565UBU465PT4ZBRC2XV4Y/ redoing the change on the main branch: https://bugs.openjdk.org/browse/JDK-8390617 Quality Outreach: https://wiki.openjdk.org/spaces/quality/pages/18448461/Quality+Outreach JavaOne: https://javaone.com
JDK 28:
early-access builds: https://inside.java/podcast/ feature list: https://openjdk.org/projects/jdk/28/
Given how prevalent Java is on web servers throughout the internet, security in Java is of critical importance. There's the security of the JDK itself, of course, which is overseen by the OpenJDK Security Group, which you should report JDK vulnerabilities to. But there are also the algorithms and features Java offers applications that are built on top of it and the cryptographic road map is an essential part of that development process. In recent years, post-quantum encryption has made big splashes but Java now also supports PEM texts and is considering the adoption of Argon2.
In this "Ask the Architects" episode of the Inside Java Podcast, recorded during JavaOne 2026, Nicolai Parlog talks to Sean Mullan, Lead of the OpenJDK Security Group and Tech Lead of the Oracle Security Libraries Team.
"Ask the Architects" is our podcast show, where we talk to experts in OpenJDK about their work on the Java language, API, and runtime.
Show notes:
OpenJDK Security Group: https://openjdk.org/groups/security/ Oracle JDK Cryptographic Roadmap: https://www.java.com/en/jre-jdk-cryptoroadmap.html Post-Quantum Hybrid Key Exchange for TLS 1.3: https://inside.java/2026/02/17/tls-post-quantum-hybrid-key-exchange/ JEP 542 - PEM Encodings of Cryptographic Objects: https://openjdk.org/jeps/542 JEP Draft for Argon2: https://openjdk.org/jeps/8377081
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