Better Tools for Immutable Data

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.

Make sure to check the JavaOne 2026 playlist.