A Developer’s Look at Java 24: Enhancements That Actually Matter
18 March 2025
On March 18, 2025, Java released its new version, Java 24. It is a non-LTS release that will receive support for six months. This release continues Java’s six-month release cadence and introduces a substantial set of enhancements, with a focus on developer productivity, performance, security, and modern language features.
If you’re new to Java development or need a refresher on how it came to be one of the most widely used programming languages today. It helps to start with a clear view of its origins and ecosystem.
In this article, we will give you an overview of JDK 24. We will also dive deep into the intricacies of the language and what new JEPs were brought in this new version.
Java 24 Features Overview
Java 24 Feature Highlights
1. Language & Syntax Enhancements
Cleaner, more expressive code with new patterns and preview features.
2. New APIs & Libraries
Advanced memory access, structured concurrency, and Scoped Values.
3. Performance & GC Improvements
Faster startup, optimized garbage collection, and improved throughput.
4. Security & Cryptography
SHA-3 enabled by default, stronger randomness, and PKCS#11 support.
5. Developer Experience
Improved javac, diagnostics, and preview toolchain support.
6. Virtual Threads & Concurrency
Easier async programming with lightweight, scalable threads.
7. Preview & Incubator Features
String templates, class-file API updates, and early-access tools.
8. Platform & Deployment
Better native integration and runtime behavior across environments.
JDK 24 introduces a focused set of enhancements aimed at improving developer runtime performance. While it is a non-LTS release, there are some features that are attracting developers towards it. It also sets the ground for the next LTS release, Java 25.
Let’s look at the key Java 24 features:
1. JEP 483: Ahead-of-Time (AOT) Class Loading and Linking
This feature gives you a way to load and link classes ahead of time instead of doing it while the program is running. You can speed up startup and improve performance by resolving classes during the build or installation phase. This is especially useful in environments where resources are limited or containers are used, where speed at startup is important. It also makes it possible to get more consistent performance in microservice deployments.
2. JEP 484: Class-File API
JEP 484 adds a new Class-File API to Java. This lets developers read, analyse, and change .class files in code. For tool developers who need to look at bytecode, write compilers, or make instrumentation tools, this is a big win. This JEP replaces the old ASM library, which makes it easier to work with low-level bytecode.
3. JEP 485: Stream Gatherers
Stream Gatherers level up Java Streams further. They let developers go beyond the built-in operations like map, filter, and flatMap, making it possible to define custom intermediate steps in a data pipeline. So, if you are working in a team handling complex data workflows, this JEP can provide you with new flexibility that the standard API is unable to.
4. JEP 491: Synchronize Virtual Threads Without Pinning
This update solves a major limitation with virtual threads. Previously, synchronized blocks could pin virtual threads to underlying platform threads, which kind of defeated the purpose of using them in the first place. With this fix, that’s no longer the case. Now, apps using Project Loom’s virtual threads can scale much more efficiently, even under heavy concurrency. Java’s now better equipped to handle thousands of lightweight threads, a big win for high-throughput workloads.
5. JEP 488: Primitive Types in Patterns and switch (Second Preview)
Java continues to modernize its pattern matching capabilities. JEP 488 brings support for primitive types in both pattern matching and switch statements, a long-awaited addition. This removes the need for unnecessary boxing and unboxing, leading to cleaner, faster code and fewer runtime surprises. It’s a step toward treating primitive types and objects more uniformly in pattern logic.
6. JEP 492: Flexible Main Constructor Bodies (Third Preview)
This feature refines how record classes and value classes can declare constructor bodies. Previously, constructor flexibility was limited. With this JEP, developers get a more expressive and flexible way to initialize components, particularly useful for records with validation logic or derived fields. It helps simplify boilerplate and improves code clarity while sticking to the principles of immutability.
7. JEP 499: Structured Concurrency (Fourth Preview)
Structured Concurrency is changing the way we write concurrent code in Java.
Instead of juggling scattered threads and executors, developers can now group related tasks and manage them as a single unit, starting them together, canceling them together, and handling failures as a whole. It makes concurrency easier to reason about, safer, and far more maintainable. With the fourth preview, Java is putting the finishing touches on this model, moving one step closer to making it a standard part of modern concurrent programming.
8. JEP 489: Vector API (Ninth Incubation)
The Vector API is steadily pushing Java toward high-performance computing. It gives developers a way to write vectorized code that’s optimized for the machine it runs on, meaning faster math on arrays and large data sets. That’s a big deal for fields like machine learning, scientific computing, finance, and image processing. While it’s still in incubation, the API is quickly maturing, bringing Java closer to native-level speed for data-parallel tasks.
Other Java 24 Enhancements
Beyond the headline features, Java 24 includes several smaller but meaningful improvements. Here’s a quick rundown of what else is new, organized by feature type and preview status:
Preview Features
JEP 456: Unnamed Patterns and Variables (Second Preview)
Introduces the use of _ as a placeholder for unused variables and patterns, reducing boilerplate and improving code readability.
JEP 457: Class-File API (Preview)
Provides a structured, programmatic way to read, write, and transform .class files — making bytecode tools safer and easier to build.
JEP 463: Implicitly Declared Classes and Instance Main Methods (Second Preview)
Simplifies Java’s syntax for beginners by allowing programs without explicit class declarations and supporting instance-based main methods. This is part of Project Amber’s ongoing effort to make Java more approachable.
Incubator / Experimental Features
JEP 487: Scoped Values (Fourth Preview)
Allows immutable, shareable data to be safely passed down call chains — a key building block for efficient, thread-safe programming with virtual threads. This is no longer an incubator feature; it’s in its fourth preview.
Note: There’s no confirmed JEP 472 or “External Heap Memory” feature in Java 24. That entry appears to be incorrect or speculative.
Ongoing Preview Features
JEP 430: String Templates (Second Preview)
Brings string interpolation to Java through a flexible templating mechanism, supporting both built-in and custom formatters. Still in preview, but steadily progressing.
Language & Syntax Enhancements in Java 24
Java 24 Language & Syntax Enhancements
1. Primitive Types in Pattern Matching
Use int, double, etc., directly in switch and patterns — no boxing needed.
2. Flexible Record Constructors
Add custom logic in main record constructors without compact syntax.
3. Unnamed Variables & Patterns
Use _ to ignore irrelevant values in patterns or lambdas for cleaner code.
4. Implicit Classes & Main Methods
Write top-level code without declaring a class or main method — ideal for beginners and quick scripts.
Java 24 keeps chipping away at the rough edges of the language, and this release brings some sharp refinements to syntax and structure. The focus here isn’t on flashy new paradigms, but on making the core Java experience smoother: cleaner code, fewer workarounds, and a little less boilerplate every time you write a method or declare a pattern. These updates may seem subtle on the surface, but together they nudge Java closer to being the expressive, modern language developers have been asking for.
Here’s a closer look at the key Java syntax updates and language improvements introduced in JDK 24:
1. Primitive Types in Patterns and switch (JEP 488 – Second Preview)
Pattern matching just got a lot more practical.
With Java 24, you can now use primitive types like int, double, and boolean directly in switch statements and type patterns — no more awkward boxing or clunky workarounds. This small-but-mighty update cuts down on verbosity and helps avoid the performance costs that used to sneak in when primitives weren’t first-class citizens in pattern matching.
Example:
static String classifyNumber(int n) {
return switch (n) {
case 0 -> “Zero”;
case int i when i > 0 -> “Positive”;
case int i when i < 0 -> “Negative”;
default -> “Unknown”;
};
}
2. Flexible Main Constructor Bodies (JEP 492 – Third Preview)
JEP 492 continues the refinement of record and value class constructors. In this update, developers gain the ability to include custom initialization logic inside the main constructor without resorting to compact constructors.
This improves flexibility while preserving immutability and encapsulation, especially for records that require validation or calculated fields during instantiation.
Example:
record Order(String product, int quantity) {
Order {
if (quantity <= 0) throw new IllegalArgumentException(“Quantity must be positive”);
}
}
3. Unnamed Variables and Patterns (JEP 456 – Second Preview)
This update eliminates the need for dummy names or extraneous code to appease the compiler by allowing you to use _ as a placeholder for variables or pattern elements you wish to ignore. Although it’s a minor adjustment, it clarifies your intent and makes your code easier to read, particularly in pattern matching, lambdas, and deconstruction where certain values are irrelevant.
Example:
record Point(int x, int y) {}
void process(Point p) {
if (p instanceof Point(int x, _)) {
System.out.println(“Only care about x: ” + x);
}
}
4. Implicitly Declared Classes and Main Methods (JEP 463 – Second Preview)
You can write basic programs without enclosing everything in a class or method declaration thanks to this preview feature. No more printing “Hello, world” with public static void main(String[] args). Java now feels less daunting and more approachable, which is a welcome change for beginners. It’s ideal for short scripts, quick experiments, or that initial “getting it” moment.
Example:
System.out.println(“Hello, Java 24!”);
New APIs & Libraries in Java 24
1. Structured Concurrency (JEP 482)
Manage related threads as a unit for cleaner, safer concurrency.
2. Class-File API (JEP 457)
Standardized way to read/write .class files — no more third-party tools.
3. Foreign Function & Memory API (JEP 454)
Call native libraries and access off-heap memory — no JNI required.
4. Scoped Values (JEP 447)
A safer alternative to thread-local variables for sharing context.
Java 24 delivers a thoughtful expansion of its standard API toolkit, introducing new capabilities and refining existing ones to align with modern development needs. Here’s a breakdown of the most important Java API enhancements and new libraries in Java 24 that developers should be aware of:
1. Structured Concurrency API (JEP 482 – Second Preview)
Structured Concurrency is Java’s answer to tangled thread management.
Still in preview, this API lets you treat a group of related tasks as a single unit — so you can start them together, cancel them together, and handle failures in a clean, predictable way. With StructuredTaskScope, Java makes concurrent programming not just safer, but actually manageable. Fewer thread leaks, less chaos, and code that’s much easier to reason about.
Example:
try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
Future<String> user = scope.fork(() -> findUser());
Future<Integer> order = scope.fork(() -> findOrder());
scope.join();
scope.throwIfFailed();
System.out.println(user.result() + ” – ” + order.result());
}
2. Class-File API (JEP 457 – Preview)
The Class-File API brings structure to the wild west of bytecode tooling. In preview, this new API gives developers a standard way to read, write, and transform .class files. Previously, completing this task required third-party libraries, which have now been replaced. This makes building compilers, IDEs, or static analysis tools easier.
3. Foreign Function & Memory API (JEP 454 – Fourth Preview)
The Foreign Function & Memory API is getting closer to prime time. Refined again in Java 24, this evolving API lets Java code call native libraries and work with off-heap memory safely, efficiently, and without the headache of JNI. It opens the door to high-performance native integrations, making Java a stronger fit for use cases like AI/ML, game development, and low-level systems programming.
Example:
try (Arena arena = Arena.ofConfined()) {
MemorySegment segment = arena.allocate(100);
// Use native memory safely
}
4. Scoped Values (JEP 447 – Second Preview)
In concurrent code, scoped values challenge the way we pass context. Scoped values provide a more secure and reliable method of sharing data across call chains than thread-local variables and mutable state. They perform exceptionally well in contemporary concurrency configurations, particularly when combined with virtual threads or structured concurrency, which facilitates context management without the typical drawbacks.
Other API & Library Improvements
Alongside the headline updates, Java 24 includes several smaller but valuable improvements:
- Pattern Matching API Enhancements: Continued refinement of the Pattern and Matcher classes for better regex handling and readability.
- Improved Collections Utilities: Subtle updates to improve the ergonomics and performance of core collections.
- Date & Time Enhancements: Minor but welcome additions to java.time that simplify common tasks like timezone handling and formatting.
Performance & GC Improvements in Java 24
Here are the most notable performance improvements and GC updates in Java 24:
1. Generational ZGC (JEP 439 – Second Preview)
Java now has smarter garbage collection thanks to Generation ZGC. This update, which is based on the ultra-low-latency ZGC, offers distinct memory areas for young and old objects, which is a significant performance improvement. Generational ZGC can now gather Java objects more frequently and effectively without affecting the long-lived ones because the majority of them are short-lived. Better throughput, smoother performance at scale, and less GC overhead are the outcomes.
2. JVM Performance Optimizations
Behind the scenes, the JVM has been fine-tuned with smarter JIT compiler heuristics, improved escape analysis, and targeted fixes for common performance bottlenecks. These under-the-hood upgrades enable better memory handling and faster execution across various architectures, including Java platforms such as Jakarta EE and Spring Boot, where efficient performance is crucial. Especially in apps with lots of method calls or heavy object allocation, all without touching your code.
3. Memory Management Enhancements
Memory management in Java 24 gets a quiet but meaningful upgrade. This release fine-tunes how the JVM allocates and reuses memory, with improvements like smarter sizing of thread-local allocation buffers (TLABs), reduced allocation contention in multi-threaded scenarios, and better resizing of internal caches and buffers. The result? Java apps that run leaner, scale more smoothly, and hold up better under heavy concurrency.
4. Improved Monitoring & Diagnostics
Java 24 improves observability and makes it more production-friendly. Even in live environments, developers can now access better Java Flight Recorder (JFR) events related to memory and garbage collection, richer GC logs with more actionable metrics, and lower-overhead profiling. It’s simpler to identify performance problems early, adjust resource usage, and maintain your app’s functionality under stress when you have access to more accurate data.
Java Modernization Guide: Adopting Java 24 the Right Way
Java Modernization Guide
1. Audit Your Codebase
Identify deprecated APIs and outdated libraries to prevent runtime issues.
2. Adopt Features Strategically
Start with preview features in isolated modules — don’t rush full adoption.
3. Use Multi-Release JARs
Target Java 24 while keeping builds compatible with older versions.
4. Upgrade Your Toolchain
Ensure Maven/Gradle, CI/CD, and containers are Java 24-ready.
5. Revisit Security Configs
Update cryptography settings and TLS defaults for stronger protection.
6. Train Your Team
Support adoption with docs, training, and collaborative reviews.
Java has stood at the front in enterprise development or for backend support. So, it’s wise to keep updating it. While modernizing Java is no easy task, it can be done with right and proper decision. This section here gives you an overview of the steps. But if you find it complex then hire Java developers to do the task for you.
Now, let’s look at the roadmap to adopting Java 24 effectively and future-proofing your Java development practices.
1. Audit Your Current Java Codebase
Before upgrading to Java 24, perform a comprehensive audit of your codebase. Identify deprecated APIs, outdated libraries, and language features that may cause compatibility issues. Tools like jdeprscan and IDE inspections can flag obsolete or problematic code early. Make sure you don’t skip this part at all cost. If you do then facing runtime errors or poor performance will be inevitable.
2. Embrace Java 24 Features Strategically
Java 24 introduces several modern capabilities—from unnamed classes and instance main methods to stream gatherers and enhanced structured concurrency. But not every feature needs to be adopted immediately.
Best practice: Start small by enabling preview features in isolated modules. Gradually refactor parts of your application to adopt new language enhancements, performance tuning options, and API integrations introduced in Java 24.
3. Use Multi-Release JARs for Backward Compatibility
If you’re maintaining a codebase that needs to support multiple Java versions, multi-release JARs (MRJARs) let you target Java 24’s features while still shipping compatible builds for older runtimes.
Pro tip: This approach is ideal when you want to introduce new capabilities gradually without breaking existing deployments.
4. Modernize Your Build and Deployment Toolchain
Upgrade your tooling to fully support Java 24, and consider whether your current Java frameworks are compatible with the language’s new concurrency model and performance improvements. Ensure your build tools (Maven, Gradle), CI/CD pipelines, and container configurations are Java 24-ready, and take time to evaluate which Java technologies and tools align best with your development stack. Also, use modern JVM options to unlock performance and observability improvements.
Optimize for performance: Adopt the Generational ZGC or G1 enhancements introduced in Java 24 to reduce pause times and memory overhead.
5. Revisit Your Security Posture
With ongoing improvements to cryptographic APIs and secure defaults, now is a good time to revisit your application’s security configuration. Replace legacy hash functions, update TLS configurations, and test new default behaviors to ensure secure-by-design deployments.
6. Invest in Training & Documentation
Your team may need time to ramp up on Java 24’s new features and idioms. Invest in updated documentation, internal code guidelines, and hands-on training to ensure consistent and correct usage of new language constructs.
Tip: Encourage pair programming and code reviews to reinforce best practices during the transition.
Final Thoughts
Java 24 isn’t a dramatic overhaul but that’s never really been the spirit of the language, especially when you compare it to C++ in terms of evolution style and core design. Instead, it continues Java’s steady, deliberate evolution, offering meaningful enhancements that make everyday development just a bit smoother, more secure, and more efficient.
From small syntax refinements to thoughtful API additions and performance improvements under the hood, these updates show a language still very much alive, growing alongside the needs of modern developers without abandoning its core principles of stability, clarity, and portability.
If you’re already working in the Java ecosystem, Java 24 is a natural next step. And if you find it too complex to understand them, hire Java developers who can guide you appropriately through your project.
FAQs
1. What is Java 24 and why is it important?
Java 24 is the latest release in the Java platform’s regular six-month release cycle. It introduces several language enhancements, new APIs, performance optimizations, and improved security features. Staying updated helps developers write cleaner, more efficient code and keep applications modern and secure.
2. Is Java 24 a Long-Term Support (LTS) version?
No, Java 24 is not an LTS version. The most recent LTS version is Java 21. Java 24 is a feature release intended for developers who want early access to new capabilities and are comfortable working with preview and incubator features.
3. Can I use Java 24 in production applications?
Yes, but with caution. While the stable features are production-ready, preview and incubator features are subject to change or removal in future versions. Always test thoroughly and check for feature stability before deploying in production.
4. What are the key performance improvements in Java 24?
Java 24 enhances the Generational ZGC and G1 Garbage Collector, improving memory efficiency and reducing pause times. These updates are particularly beneficial for large-scale and real-time applications where latency matters.
6. What tools should I update before migrating to Java 24?
Before upgrading, ensure your build tools (like Maven or Gradle), IDEs, testing frameworks, and CI/CD pipelines are compatible with Java 24. Also, update any libraries that may depend on deprecated APIs or outdated Java features.
reza@terralogiq.com
Reza Riwanda
