💡JDK 28 Integrates JEP 401 for Value Classes

Value classes in JDK 28 could change how you write Java

JDK 28 has integrated JEP 401, introducing value classes that increase the ability to communicate program semantics and optimization opportunities. However, these classes don't guarantee a performance floor, meaning a well-intentioned program might end up slower in some cases. Immutability enables flattening, allowing the JVM to choose a suitable representation for a particular situation without the requirement of identity. The strict-initialization guarantee in JEP 539 lets the JVM rely on a final field having been initialized before its enclosing object becomes observable, opening up many optimization possibilities. The JVM can store a final field using a non-atomic flattened layout, but tearing issues can prevent flattening for large values. This impacts developers using Java for performance-critical applications, as the JVM's ability to optimize code depends on the compiler proving that identity has no impact on computation.