What’s New in JDK 23? A Quick Tour of 12 Game‑Changing Features

On September 17, Oracle released JDK 23, the latest version of the Java programming language and platform, bringing thousands of improvements aimed at productivity, performance, stability and security.

JDK 23 introduces twelve preview features:

JEP 455: Primitive types in pattern matching, instanceof and switch.

JEP 466: Class‑file API (second preview) for parsing, generating and transforming class files.

JEP 467: Markdown support in Javadoc comments.

JEP 469: Eighth incubation of the Vector API.

JEP 471: Deprecation of memory‑access methods in sun.misc.Unsafe.

JEP 473: Stream collectors (second preview) enhancing the Stream API with custom intermediate operations.

JEP 474: ZGC generational mode, switching Z Garbage Collector to a generational algorithm for better performance.

JEP 476: Module import declarations (preview) allowing concise import of all packages exported by a module.

JEP 477: Implicitly declared classes and instance main methods (third preview) simplifying the first program for beginners.

JEP 480: Structured concurrency (third preview) adding an API to simplify concurrent programming.

JEP 481: Scoped values (third preview) enabling immutable data sharing within and across threads.

JEP 482: Flexible constructor bodies (second preview) permitting statements before an explicit constructor call.

To cope with such rapid language evolution, the article recommends relying on the timeless programming principles compiled in Effective Java (3rd edition). The book distills 90 guidelines covering object creation, method design, class and interface usage, generics, enums, annotations, lambda expressions, streams, concurrency, serialization and more. By internalizing these principles, developers can write readable, maintainable, robust and efficient Java code regardless of new language features.

Applying the core ideas from Effective Java—such as favoring composition over inheritance, minimizing mutability, using appropriate APIs, and embracing functional constructs—helps programmers adapt to JDK 23’s additions without being overwhelmed.