Java 25 LTS is a Long-Term Support (LTS) release. It brings several features that can improve a blog application in performance, concurrency, security, and code clarity.
Here are some key Java 25 features and how you can use them to create a blog with new features:
Java 25, released on September 16, 2025, is a Long-Term Support (LTS) release that follows Java 21. It offers stability due to its long support period and includes several improvements in language, libraries, performance, and security.
Here are the key features in Java 25, organized by focus:
I. Concurrency and Context (Finalized)
These features make it easier to build modern, high-throughput applications, especially when using Virtual Threads from a previous release.
Scoped Values (JEP 506): After five iterations, this feature is now a modern, safe, and efficient substitute for ThreadLocal. It enables sharing immutable data, like a request ID or user context, with less overhead across a thread and its child threads. It also ensures an automatically limited lifetime.
Structured Concurrency (JEP 505, Fifth Preview): This continues to improve the API for treating related concurrent tasks as one unit of work. It enhances error handling, cancellation, and observability.
II. Language Usability (Finalized)
These JEPs aim to cut down on repetitive code and make Java easier for beginners while also making it more concise for experienced developers.
Flexible Constructor Bodies (JEP 513): This allows statements, such as argument validation or calculations, to occur before the required super(…) or this(…) constructor call. This enables “fail-fast” validation without needing helper methods, which improves object safety and constructor clarity.
Compact Source Files and Instance Main Methods (JEP 512): This makes it easier to write small programs by allowing code without a class declaration (unnamed classes) and simplifying the main method signature (for example, void main()). This reduces repetitive code for scripts and beginner programs.
Module Import Declarations (JEP 511): This allows importing all exported packages of a module with a single declaration (for example, import module java.base;), which streamlines the use of modular libraries.
III. Performance and Runtime (Finalized)
These features improve the JVM’s efficiency and monitoring tools.
Compact Object Headers (JEP 519): Now a product feature, this reduces the size of object headers on 64-bit systems. It results in lower memory usage, higher heap density, and better performance.
Generational Shenandoah (JEP 521): This makes the low-pause Shenandoah Garbage Collector generational, which further boosts its efficiency, especially for programs with high allocation rates.
Ahead-of-Time Method Profiling (JEP 515) and Command-Line Ergonomics (JEP 514): Improvements to the Ahead-of-Time (AOT) infrastructure for faster application startup and quicker warmup times.
Java 25, released on September 16, 2025, is a Long-Term Support (LTS) release, succeeding Java 21. It provides stability with a long support window and includes numerous enhancements across language, libraries, performance, and security.
Here are the key features delivered in Java 25, categorized by their focus:
I. Concurrency and Context
These features simplify modern, high-throughput applications, especially when using Virtual Threads (introduced in a previous release).
- Scoped Values (JEP 506): Finalized after five iterations, this is the modern, safe, and efficient replacement for
ThreadLocal. It allows sharing immutable data (like a request ID or user context) with lower overhead across a thread and its child threads, with an automatically bounded lifetime. - Structured Concurrency (JEP 505, Fifth Preview): Continues to refine the API for treating related concurrent tasks as a single unit of work, improving error handling, cancellation, and observability.
II. Language Usability
These JEPs aim to reduce boilerplate and make Java more accessible for beginners and more concise for experienced developers.
- Flexible Constructor Bodies (JEP 513): Allows statements (like argument validation or calculation) to appear before the required
super(...)orthis(...)constructor call. This enables “fail-fast” validation without helper methods, improving object safety and constructor clarity. - Compact Source Files and Instance Main Methods (JEP 512): Simplifies the entry point for small programs by allowing code without a class declaration (unnamed classes) and simplifying the
mainmethod signature (e.g.,void main()), reducing boilerplate for scripts and beginner code. - Module Import Declarations (JEP 511): Allows importing all exported packages of a module with a single declaration (e.g.,
import module java.base;), which streamlines the use of modular libraries.
III. Performance and Runtime
These features enhance the JVM’s efficiency and monitoring capabilities.
- Compact Object Headers (JEP 519): Promoted to a product feature, this reduces the size of object headers on 64-bit architectures, leading to lower memory usage, higher heap density, and improved performance.
- Generational Shenandoah (JEP 521): Makes the low-pause Shenandoah Garbage Collector generational, further improving GC efficiency, especially for programs with high allocation rates.
- Ahead-of-Time Method Profiling (JEP 515) and Command-Line Ergonomics (JEP 514): Improvements to the Ahead-of-Time (AOT) infrastructure for faster application startup and quicker warmup times.
IV. Security and Libraries (Finalized and Preview)
PEM Encodings of Cryptographic Objects (JEP 470, Preview): Provides an API for encoding/decoding cryptographic objects (keys, certificates) using the widely used PEM transport format.
Key Derivation Function API (JEP 510): Introduces a standard API for Key Derivation Functions (KDFs) like PBKDF2 and Argon2, standardizing modern, secure password hashing algorithms within the JDK.
Primitive Types in Patterns, instanceof, and switch (JEP 507, Third Preview): Extends pattern matching to work directly with all primitive types, leading to cleaner code when handling and destructuring primitives.
Java 25 is an LTS release offering features that can greatly improve a blog application’s performance, code clarity, and security. Below are code examples demonstrating two key features: Scoped Values and Flexible Constructor Bodies.
I. Feature: Scoped Values
New Feature Idea: Seamlessly Pass Request Context (e.g: User ID)
In a concurrent web application (like a blog’s backend using Virtual Threads), you often need to access data related to the current request (like the logged-in user’s ID) deep within the call chain without passing it through every method signature. Scoped Values replace error-prone ThreadLocal variables by being immutable and automatically cleared when the scope ends.
import java.lang.ScopedValue;
import java.util.concurrent.Executors;
// 1. Declare the Scoped Value key, typically static final
public class BlogContext {
// The ScopedValue is unbound by default and thread-safe
public static final ScopedValue<String> USER_ID = ScopedValue.newInstance();
}
public class RequestHandler {
// Simulate a main request entry point for a blog
public void handlePostRequest(String userId, String postId) {
// 2. Bind the value for the execution scope
ScopedValue.where(BlogContext.USER_ID, userId)
.run(() -> {
System.out.println("Handler: Request started for User ID: " + BlogContext.USER_ID.get());
new CommentService().fetchComments(postId);
// The value is automatically cleared when 'run' finishes
});
}
}
class CommentService {
public void fetchComments(String postId) {
// 3. The value is implicitly accessible here
String currentUserId = BlogContext.USER_ID.get();
System.out.println(" CommentService: Fetching comments for Post " + postId +
" on behalf of user " + currentUserId);
new AnalyticsService().logActivity();
}
}
class AnalyticsService {
public void logActivity() {
// The value is still accessible deeper in the call chain
String currentUserId = BlogContext.USER_ID.get();
System.out.println(" Analytics: Logged activity for user " + currentUserId);
}
}
// Main method to run the example
class BlogApp {
public static void main(String[] args) {
var handler = new RequestHandler();
// Use an Executor for virtual threads for better concurrency simulation
try (var executor = Executors.newVirtualThreadPerTaskExecutor()) {
executor.submit(() -> handler.handlePostRequest("Alice_123", "post-A"));
executor.submit(() -> handler.handlePostRequest("Bob_456", "post-B"));
} catch (Exception e) {
Thread.currentThread().interrupt();
}
}
}
// Expected (interleaved) Output:
// Handler: Request started for User ID: Bob_456
// CommentService: Fetching comments for Post post-B on behalf of user Bob_456
// Analytics: Logged activity for user Bob_456
// Handler: Request started for User ID: Alice_123
// CommentService: Fetching comments for Post post-A on behalf of user Alice_123
// Analytics: Logged activity for user Alice_123II. Feature: Primitive Types in Patterns, instanceof, and switch
This feature extends Java’s powerful pattern matching capabilities, which previously worked only with reference types, to now include all eight primitive types (int, long, double, char, etc.).
The Problem It Solves: Before this feature, checking the type of an Object and then acting upon it if it was a primitive type (wrapped in its corresponding wrapper class like Integer) required explicit casting and couldn’t be seamlessly integrated into modern switch expressions.
Before Java 25
You had to use a series of if-else instanceof checks with explicit casting. A switch statement wouldn’t work elegantly for this kind of type-based dispatch.
// Old way of handling mixed types
void printValue(Object obj) {
if (obj instanceof Integer i) {
System.out.println("It's an integer: " + i);
} else if (obj instanceof Double d) {
System.out.println("It's a double: " + d);
} else if (obj instanceof String s) {
System.out.println("It's a String: " + s);
} else {
System.out.println("Unknown type");
}
}After Java 25 (with Primitive Patterns)
You can now use a switch statement that directly patterns matches on primitive types. The code is far more declarative, concise, and readable.
public class Java25Class {
void printValue(Object obj) {
switch (obj) {
case Integer i -> System.out.println("It's a primitive int: " + i);
case Double d -> System.out.println("It's a primitive double: " + d);
case String s -> System.out.println("It's a String: " + s);
default -> System.out.println("Unknown type");
}
}
public void main() {
// How you would use it:
printValue(42); // Output: It's a primitive int: 42
printValue(3.14159); // Output: It's a primitive double: 3.14159
printValue("Hello Java 25!"); // Output: It's a String: Hello Java 25!
printValue(42);
}
}
Benefit: This eliminates verbose if-else chains and brings the full power and safety of pattern matching switch expressions to all data types in Java.
III. Feature: Flexible Constructor Bodies
This feature allows statements to be placed before an explicit constructor invocation (this(...) or super(...)).
The Problem It Solves: Previously, the very first statement in a constructor had to be a call to another constructor in the same class (this(...)) or a superclass constructor (super(...)). This made it impossible to perform validation or pre-processing on arguments before passing them up the chain.
Before Java 25
Developers had to use cumbersome workarounds, like static factory methods, to validate or sanitize arguments before calling the constructor.
// Old workaround using a static helper method
class Range {
private final int start;
private final int end;
// The constructor couldn't validate before calling super() or this()
private Range(int start, int end) {
this.start = start;
this.end = end;
}
// Static factory method was needed for validation
public static Range of(int start, int end) {
if (start > end) {
throw new IllegalArgumentException("Start cannot be after end");
}
return new Range(start, end);
}
}After Java 25 (with Flexible Constructors)
You can now place logic directly inside the constructor before the this() or super() call, as long as that logic doesn’t access the instance (this) being created.
// New, direct approach
class Range {
private final int start;
private final int end;
// A canonical constructor
public Range(int start, int end) {
this.start = start;
this.end = end;
}
// Another constructor that can now validate *before* delegating
public Range(int end) {
// This logic is now allowed before the this() call!
int calculatedStart = Math.max(0, end - 10);
if (end < 0) {
throw new IllegalArgumentException("End cannot be negative");
}
// The call to this() is no longer the first statement
this(calculatedStart, end);
}
}Benefit: This simplifies constructor logic, eliminates the need for certain static factory methods, and makes the code flow more naturally and intuitively.
IV. Module Import Declarations
This feature simplifies how you work with the Java Platform Module System (JPMS) by allowing you to import an entire module’s worth of packages with a single declaration.
The Problem It Solves: When a module exports many packages (like Google’s Guava library), a consuming module had to explicitly import each required package in its source files. This could lead to a long list of import statements.
This feature simplifies how you work with the Java Platform Module System (JPMS) by allowing you to import an entire module’s worth of packages with a single declaration.
The Problem It Solves: When a module exports many packages (like Google’s Guava library), a consuming module had to explicitly import each required package in its source files. This could lead to a long list of import statements.
Before Java 25
You would have a standard requires clause in your module-info.java file and then a potentially long list of imports in your Java source file.
module-info.java (Before):
module com.my.app {
requires com.google.common; // Requires the entire module
}MyApp.java (Before):
// Many individual package imports are needed
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.base.Strings;
import com.google.common.math.IntMath;
public class MyApp {
// ... code using these classes
}Of course. Here are detailed explanations and code examples for the Java 25 features you asked about. These features aim to modernize the language, reduce boilerplate, and make code more intuitive and readable.
V. Flexible Constructor Bodies
This feature allows statements to be placed before an explicit constructor invocation (this(...) or super(...)).
The Problem It Solves: Previously, the very first statement in a constructor had to be a call to another constructor in the same class (this(...)) or a superclass constructor (super(...)). This made it impossible to perform validation or pre-processing on arguments before passing them up the chain.
Before Java 25
Developers had to use cumbersome workarounds, like static factory methods, to validate or sanitize arguments before calling the constructor.
Java
// Old workaround using a static helper method
class Range {
private final int start;
private final int end;
// The constructor couldn't validate before calling super() or this()
private Range(int start, int end) {
this.start = start;
this.end = end;
}
// Static factory method was needed for validation
public static Range of(int start, int end) {
if (start > end) {
throw new IllegalArgumentException("Start cannot be after end");
}
return new Range(start, end);
}
}
After Java 25 (with Flexible Constructors)
You can now place logic directly inside the constructor before the this() or super() call, as long as that logic doesn’t access the instance (this) being created.
Java
// New, direct approach
class Range {
private final int start;
private final int end;
// A canonical constructor
public Range(int start, int end) {
this.start = start;
this.end = end;
}
// Another constructor that can now validate *before* delegating
public Range(int end) {
// This logic is now allowed before the this() call!
int calculatedStart = Math.max(0, end - 10);
if (end < 0) {
throw new IllegalArgumentException("End cannot be negative");
}
// The call to this() is no longer the first statement
this(calculatedStart, end);
}
}
Benefit: This simplifies constructor logic, eliminates the need for certain static factory methods, and makes the code flow more naturally and intuitively.
VI. Module Import Declarations
This feature simplifies how you work with the Java Platform Module System (JPMS) by allowing you to import an entire module’s worth of packages with a single declaration.
The Problem It Solves: When a module exports many packages (like Google’s Guava library), a consuming module had to explicitly import each required package in its source files. This could lead to a long list of import statements.
Before Java 25
You would have a standard requires clause in your module-info.java file and then a potentially long list of imports in your Java source file.
module-info.java (Before):
Java
module com.my.app {
requires com.google.common; // Requires the entire module
}
MyApp.java (Before):
Java
// Many individual package imports are needed
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.base.Strings;
import com.google.common.math.IntMath;
public class MyApp {
// ... code using these classes
}
After Java 25 (with Module Imports)
You can use an import module statement to make all exported packages from that module available to the compilation unit.
module-info.java (After):
module com.my.app {
requires com.google.common;
}
MyApp.java (After):
// A single import for the entire module!
import module com.google.common;
public class MyApp {
public void process() {
// We can now use simple names for classes from any exported package
var list = ImmutableList.of("a", "b", "c");
var padded = Strings.padStart("test", 10, '0');
var factorial = IntMath.factorial(5);
System.out.println(list + ", " + padded + ", " + factorial);
}
}Benefit: It significantly reduces the number of import statements needed, decluttering source files and making it easier to use large, multi-package libraries.
VII. Compact Source Files and Instance Main Methods
These features are part of an effort to lower the barrier to entry for Java beginners, making the classic “Hello, World!” program much simpler.
The Problem It Solves: Java’s entry point ceremony (public class HelloWorld { public static void main(String[] args) { ... } }) is verbose and can be intimidating for newcomers.
A) Instance Main Methods
Before Java 25: The main method had to be public, static, and void. Accessing instance members required creating an object of the class.
public class Greeter {
private final String greeting = "Hello, Java!"; // An instance field
// The classic static main method
public static void main(String[] args) {
Greeter app = new Greeter(); // Must create an instance to access the field
app.run();
}
void run() {
System.out.println(greeting);
}
}After Java 25: The main method can now be an instance method (non-static). The Java launcher will automatically instantiate the class and call this main method.
class Greeter {
private final String greeting = "Hello, simplified Java!"; // An instance field
// The new, non-static main method
void main() {
// Can directly access instance fields!
System.out.println(greeting);
}
}B) Compact Source Files (Implicitly Declared Classes)
Combining an instance main method with implicitly declared classes makes it even simpler.
Before Java 25: Even for a single line of output, you needed a full class definition.
// HelloWorld.java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}After Java 25: You can write a file with just a main method. The compiler implicitly considers it the main method of an unnamed class.
// helloworld.java (no class declaration needed!)
void main() {
System.out.println("Hello, from a compact source file!");
}Benefit: These changes dramatically lower the boilerplate required for simple programs, making Java much more approachable for teaching, scripting, and quick prototyping.
Conclusion
Java 25, as the latest Long-Term Support (LTS) release, represents a significant consolidation of features aimed at improving developer productivity, cloud-native concurrency, and runtime performance.
The release’s core theme is refinement and robust finalization:
- Concurrency is safer and cleaner with the final delivery of Scoped Values (JEP 506), which provides a thread-safe, leak-proof alternative to
ThreadLocalvariables for passing request context. - Language clarity is paramount through features like Flexible Constructor Bodies (JEP 513) for fail-fast validation and Compact Source Files (JEP 512) for removing boilerplate in small programs.
- Performance and stability are enhanced by JVM-level improvements like Compact Object Headers (JEP 519) and Generational Shenandoah (JEP 521).
In conclusion, Java 25 is a critical and stable platform that makes writing highly concurrent, robust, and concise code easier than ever, securing Java’s relevance for enterprise and cloud applications for years to come.