We'll review new and upcoming Java features that improve the convenience, reliability, and performance of immutable data, including:

- Records, record patterns, and derived record creation
- Value classes and objects
- Early field initialization with flexible constructor bodies
- The lazy constants API
- Initialization diagnostics for static final fields
- Unsafe reflective mutation or deserialization and the marshalling API as an alternative
- In the future: immutable arrays?

We'll discuss how these features complement each other, what sorts of JVM optimizations they enable, and how to decide when they're a good fit for an application.

Presented by Dan Smith (Oracle) at JavaOne 2026 (CA, March 2026).

See also https://youtu.be/fFocVFEe2TI

All https://www.youtube.com/playlist?list=PLX8CzqL3ArzUMVSzm-z_-if8BIB55EGl4 talks.

* https://openjdk.org/projects/amber/
* https://inside.java/tag/amber
* https://openjdk.org/projects/valhalla/
* https://inside.java/tag/valhalla

Tags: #Java #JavaOne

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Better Tools for Immutable Data