JDK 24 is the latest non‐LTS release in Oracle’s six‐month cadence, with its official release scheduled for March 18, 2025. This version is notable for its record number of JEPs—each addressing modern challenges in performance, usability, and security. Whether you’re a seasoned enterprise developer or a newcomer learning Java, there’s something in JDK 24 that will reshape how you write and run your code.
Enhanced Garbage Collection and Performance
Generational Shenandoah (JEP 404 – Experimental)
One of the headline features is the experimental “Generational Shenandoah” garbage collector mode. Traditionally, Shenandoah operated without distinguishing between young and old objects. Now it can allocate objects in separate generations, which helps reduce pause times and optimize memory usage—paving the way for a future where low-latency garbage collection is the norm.
Late Barrier Expansion for G1 (JEP 475)
G1’s performance has also received a boost thanks to “Late Barrier Expansion.” By deferring the insertion of GC barriers until later in the compilation pipeline, Java reduces overhead and streamlines the just-in-time compilation process, translating into 10–20% faster application performance in some cases.
ZGC: Removal of Non-Generational Mode (JEP 490)
With ZGC, the non-generational mode is finally removed—forcing all users into the more efficient generational mode. This change reduces complexity and helps ensure that ZGC continues to deliver ultra-low pause times for modern applications.
Virtual Threads and Concurrency Enhancements
Synchronize Virtual Threads without Pinning (JEP 491)
Virtual threads have been a game-changer in scaling concurrent Java applications. However, earlier versions forced virtual threads into a “pinned” state when entering synchronized blocks, limiting overall scalability. JEP 491 fixes this by allowing virtual threads to unpin their underlying platform threads—even within synchronized sections—thus increasing concurrency without code changes.
Structured Concurrency (JEP 499 – Fourth Preview)
Structured Concurrency refines the way developers manage groups of concurrent tasks. By treating related threads as a single unit of work, this preview feature simplifies error handling and cancellation, making multithreaded programming more robust and easier to maintain.
Scoped Values (JEP 487 – Fourth Preview)
Replacing some of the traditional uses of ThreadLocal, Scoped Values provide a cleaner and more efficient mechanism to share immutable data between methods and even across child threads. This feature improves both performance and code clarity when working with virtual threads and structured concurrency.
Startup, Class-Loading, and API Enhancements
Ahead-of-Time Class Loading & Linking (JEP 483)
To tackle slow startup times, JDK 24 introduces ahead-of-time class loading and linking. This feature caches the loaded and linked forms of classes during a “training run” so that subsequent application starts can bypass much of the heavy lifting—cutting startup times significantly.
Class-File API (JEP 484)
Java’s ecosystem has long depended on third-party libraries like ASM for bytecode manipulation. The finalized Class-File API now provides an official, evolving standard for reading, generating, and transforming class files—ensuring that tool developers can always work with the latest class formats without external dependencies.
Stream Gatherers (JEP 485)
Enhancing the Stream API, Stream Gatherers allow developers to define custom intermediate operations. This new capability makes it easier to write concise, expressive data pipelines and opens up possibilities for tailor-made stream processing that goes beyond the built-in operations.
Language and Developer Experience Improvements
Primitive Types in Patterns, instanceof, and switch (JEP 488 – Second Preview)
Java’s pattern matching features expand further in JDK 24 to include primitive types—allowing more natural, concise, and safe operations in instanceof tests and switch expressions. This improvement minimizes boilerplate code and reduces the risk of data loss during type conversion.
Flexible Constructor Bodies (JEP 492 – Third Preview)
For years, developers have been constrained by the rule that a constructor must call super() or this() before executing any other code. With Flexible Constructor Bodies, you can now run initialization code (such as validating constructor parameters or even initializing fields) before invoking the parent constructor, making object construction both safer and more intuitive.
Module Import Declarations (JEP 494 – Second Preview)
Importing modules becomes simpler and more powerful. Instead of writing numerous package-level import statements, you can now import an entire module with a single declaration. This streamlined approach not only reduces boilerplate but also makes Java more approachable for newcomers.
Simple Source Files and Instance Main Methods (JEP 495 – Fourth Preview)
Designed with beginners in mind, this feature lets you write small Java programs without needing to define a full class structure. Instead, you can write a simple instance main() method and use built-in shortcuts (like automatic imports for common utilities), making the “Hello World” experience smoother and less intimidating.
Vector API (JEP 489 – Ninth Incubator)
The Vector API continues to evolve, enabling developers to write code that leverages modern CPU SIMD instructions for significantly better performance in compute-intensive operations. Now incubated for the ninth time, it remains a powerful tool for high-performance computing while awaiting further refinements from Project Valhalla.
Security Enhancements
Permanently Disable the Security Manager (JEP 486)
After years of gradual deprecation, the Security Manager is now permanently disabled in JDK 24. This removal simplifies security management by shifting the focus to containerization and other modern security mechanisms, while also reducing the maintenance burden.
Quantum-Resistant Cryptography (JEP 496 & JEP 497)
With quantum computing on the horizon, JDK 24 includes implementations of the Module-Lattice-Based Key Encapsulation Mechanism (ML-KEM) and Digital Signature Algorithm (ML-DSA). These quantum-resistant cryptographic primitives enhance the security of Java applications against future threats.
Warn upon Use of sun.misc.Unsafe (JEP 498)
To encourage migration toward safer alternatives (like VarHandles and the Foreign Function & Memory API), JDK 24 now issues warnings when deprecated memory-access methods in sun.misc.Unsafe are used. This gradual phase-out helps maintain application stability and security over time.
Compact Object Headers (JEP 450 – Experimental)
Memory efficiency is improved by reducing the object header size from 96–128 bits down to 64 bits on 64-bit architectures. This experimental feature promises to save memory in large applications and improve data locality—a critical optimization for high-scale environments.
Conclusion
JDK 24 is more than just another release—it’s a substantial evolution in the Java platform. With major improvements ranging from faster startup times and enhanced garbage collection to revolutionary language features and robust security enhancements, this release is set to influence not only day-to-day programming but also the future roadmap of Java (with long-term innovations expected in JDK 25 and beyond).
As developers begin experimenting with these features—from rethinking how concurrency is managed to streamlining simple source files—JDK 24 offers the tools and improvements to build more efficient, secure, and modern Java applications.
What excites you the most about JDK 24? Share your thoughts and join the conversation!
References:
- infoq.com InfoQ article on JDK 24 and JDK 25 features
- bell-sw.com BellSoft’s overview of Java 24 features
- talent500.com Unlogged’s comprehensive guide to what’s brewing in JDK 24
- happycoders.eu HappyCoders.eu’s detailed breakdown of Java 24 features
- jdk.java.net Official JDK 24 Release Notes