Oracle has given the Java community a sneak peek at the features set to arrive in the next major release of the Java Development Kit (JDK), JDK 25, which is expected to drop this September. Among the five Java enhancement proposals (JEPs) previewed, the stable values API is officially targeted for JDK 25, alongside other notable features like enhanced primitive boxing, null-restricted value class types, value classes and objects, and derived record creation.

The stable values API, in particular, is designed to provide a more efficient way of working with immutable data. Stable values are objects that hold immutable data, allowing for the same performance optimizations as declaring a field final. However, they offer greater flexibility in terms of initialization timing, which can improve the startup of Java applications by breaking up the monolithic initialization of application state.

Enhanced primitive boxing is another key feature being previewed. This proposal aims to treat primitive types more like reference types, allowing for boxing of primitive values when used as the "receiver" of a field access, method invocation, or method reference. Additionally, it enables unboxed return types when overriding a method with a reference-typed return, and supports primitive types as type arguments.

Null-restricted value class types are also being explored, which would allow the type of a variable storing value objects to exclude null. This feature has the potential to enable more compact storage and other optimizations at runtime, both as a language feature and a virtual machine feature.

The value classes and objects proposal seeks to enhance the Java platform with value objects, which are class instances with only final fields and lack object identity. This feature aims to provide developers with a programming model for simple values, where objects are distinguished solely by their field values. The proposal also aims to maximize the freedom of the JVM to encode simple values in ways that improve memory footprint, locality, and garbage collection efficiency.

Lastly, the derived record creation feature is designed to provide a concise means of creating new record values derived from existing record values. This feature would also streamline the declaration of record classes by eliminating the need to provide explicit wither methods, which are the immutable analogue of setter methods.

With JDK 24 having just reached general availability, Oracle's preview of these features gives the Java community a glimpse into the future of the platform. As the JEPs move forward, developers can expect to see significant improvements in performance, flexibility, and overall efficiency in Java applications.

The publication of these JEPs marks an important milestone in the development of JDK 25, and Oracle's commitment to continually enhancing the Java platform. As the release date approaches, developers can expect to see more information on these features and how they can be leveraged to build more robust and efficient Java applications.