Java 28 Takes Shape: Value Objects, Generational GC, AOT Compilation & More

Oracle has published the development plan for JDK 28, a non‑LTS (feature) release scheduled for March 2027. The proposal lists six major features, plus the deprecation of the macOS/x64 port.

Value Objects (Preview)

Value objects are immutable and have no object identity. They are distinguished solely by the values of their fields, allowing the JVM to use more efficient representations. The goal is to give developers a programming model for immutable data where the == operator and all other operations compare objects by field values rather than identity. This feature is currently in preview.

Generational Shenandoah GC (Default)

The Shenandoah garbage collector will switch its default mode to generational. The non‑generational mode is deprecated and slated for removal in a future release, signaling that future development will focus on the generational approach and reducing the cost of maintaining two distinct modes. No immediate removal timeline is set.

Strictly Initialized Fields (Preview)

The JVM will introduce strictly initialized fields that must be initialized before they are read, eliminating default values such as 0 or null. For final strictly initialized fields, the value remains constant thereafter. This provides language designers targeting the JVM with a field‑initialization model offering stronger integrity guarantees than the existing model. The feature is in preview.

Simple JSON API (Incubator)

A new standard JSON API will parse and generate JSON documents without external dependencies. The aim is to let many JSON‑handling tasks be accomplished with minimal code, giving the Java platform a built‑in way to process the JSON data‑exchange format. This is currently an incubator feature.

PEM Encoding for Cryptographic Objects

An API will encode objects representing cryptographic keys, certificates, and certificate revocation lists into the widely used Privacy‑Enhanced Mail (PEM) format, and decode PEM data back into objects. This simplifies interoperability with existing tooling that expects PEM‑encoded data.

Ahead‑of‑Time (AOT) Compilation

AOT compilation is proposed for JDK 28. The goal is to give Java applications optimized native code immediately at JVM startup, shortening startup and warm‑up times. The proposal targets faster peak performance and sustained peak performance even when workloads change, without requiring modifications to application, library, or framework code.

Deprecation of macOS/x64 Port

To reduce maintenance overhead, the macOS/x64 port will be deprecated and eventually removed. Oracle engineers will cease maintenance from JDK 27 onward because Apple has transitioned its hardware to AArch64 and is phasing out x64 support. Removal is planned for a future JDK release.

JDK 27, the predecessor, was released on September 15. Both JDK 27 and JDK 28 are non‑LTS versions; Oracle will provide six months of customer support for each.