Java 28 starts to take shape

Plans for the Java release due in March 2027 begin with value objects, generational garbage collection, and strict field initialization in the JVM. Java Development Kit (JDK) 28, a non-LTS (Long-Term Support) or “feature release” of standard Java due in March 2027, has started to take shape. Features listed for JDK 28 now include a preview of value objects, switching the default mode of the Shenandoah generational garbage collector, and strict field initialization in the Java Virtual Machine (JVM). As a non-LTS release, JDK 28 will be backed by six months of support by Oracle. The three features currently targeted to JDK 28 include the following: Introduce value objects, which are immutable and lack object identity. Value objects are distinguished by the values of their fields, and can be represented by the JVM in ways that improve performance. A goal of the feature is to give developers a programming model for immutable data in which the == operator, and all other operations, distinguish objects by the values of their fields rather than their identities. Value objects is a preview language and VM feature. Switch the default mode of the Shenandoah Garbage Collector (GC) to the generational mode and deprecate the non-generational mode, with the intent to remove it in a future release. Goals include signaling the intent that future development will focus on generational mode, and reducing the maintenance cost of supporting two different modes. However, it is not a goal to remove non-generational mode at this time. Introduce strictly-initialized fields in the JVM. Such fields must be initialized before they are read, thus default values such as 0 or null are never observed. For strictly-initialized fields that are final, the same value is always observed. A goal is offering designers of JVM-based programming languages a model for field initialization, which has stronger integrity guarantees than the present model. This is a preview VM feature. The predecessor to JDK 28, JDK 27, is due September 15. JDK 27 also is a non-LTS release that will be backed by six months of support by Oracle.