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JEP 401 Value Objects Merged to OpenJDK Master, Landing Java's Identity-Free Objects as a Preview
The JEP 401 implementation PR (openjdk/jdk#31120) was merged to master on July 31, 2026, bringing value objects — immutable, identity-free data carriers the JVM can flatten for better memory layout and reduced GC pressure — into Java as a first preview. JEP 539's strict field initialization ships alongside it, and the standard library takes supporting changes. The HN thread drew 174 points and 94 comments. This is the long-running Valhalla work finally reaching master; anyone writing allocation-heavy JVM code should start reading the preview semantics now.
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