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Project Valhalla, Explained: How a Decade of Work Arrives in JDK 28

jvm-weekly.com

June 19, 2026

25 min read

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70/100

Summary

Project Valhalla will be integrated into the main OpenJDK repository, targeting JDK 28. JEP 401 introduces Value Classes and Objects, marking a significant advancement in the Java Virtual Machine.

Key Takeaways

Project Valhalla's JEP 401: Value Classes and Objects will be integrated into the main OpenJDK repository and is targeting JDK 28.
The integration involves over 197,000 lines of code across 1,816 files, prompting a request for remaining committers to hold off on larger commits.
Valhalla aims to allow developers to write classes that are both readable and treated as efficiently as primitives by the JVM.
The project addresses issues with Java's memory layout, aiming for a denser arrangement to improve performance and reduce cache misses.

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Analysis ready

Community Sentiment

Mixed

Positives

The introduction of value classes in Java marks a significant step towards modernizing the language, aligning it with contemporary programming practices and improving performance.
Incremental improvements in Java, such as non-nullable value types, indicate a commitment to evolving the language while maintaining backward compatibility, which is crucial for long-term adoption.

Concerns

Concerns about the stewardship of Java under Oracle suggest a lack of confidence in the direction of the language, especially when compared to the more consistent evolution seen in .NET.
The complexity introduced by value classes, particularly in how equality is handled, may lead to confusion and break encapsulation, which could negatively impact developer experience.