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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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.
Community Sentiment
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.