Java 25 Features
Java 25 Features
Major Features in Java SE 25
1. Scoped Values (Finalized)
Scoped values provide a safer alternative to thread-local variables, allowing values to be shared across threads in a controlled way.
```java
import java.util.concurrent.Executors;
import jdk.incubator.concurrent.ScopedValue;
public class ScopedValueDemo {
static final ScopedValue<String> USER = ScopedValue.newInstance();
public static void main(String[] args) {
ScopedValue.where(USER, "Alice").run(() -> {
System.out.println("Running as user: " + USER.get());
Executors.newSingleThreadExecutor().submit(() ->
System.out.println("Child thread user: " + USER.get())
);
});
}
}
```
2. Flexible Constructor Bodies
Constructors now allow more flexible initialization, improving readability and reducing boilerplate.
```java
class Person {
private final String name;
private final int age;
Person(String name, int age) {
this.name = name;
this.age = age;
System.out.println("Created person: " + name + ", age " + age);
}
}
```
3. Structured Concurrency (Preview)
Structured concurrency simplifies managing multiple tasks, ensuring proper cancellation and error handling.
```java
import java.util.concurrent.*;
public class StructuredConcurrencyDemo {
public static void main(String[] args) throws Exception {
try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
Future<String> user = scope.fork(() -> fetchUser());
Future<String> orders = scope.fork(() -> fetchOrders());
scope.join(); // Wait for all tasks
scope.throwIfFailed(); // Propagate exceptions
System.out.println(user.result() + " - " + orders.result());
}
}
static String fetchUser() { return "User: Alice"; }
static String fetchOrders() { return "Orders: 5"; }
}
```
4. Generational Shenandoah GC
Improved garbage collection with generational Shenandoah, enhancing performance for applications with mixed object lifetimes.
5. Compact Object Headers
Reduces memory footprint by optimizing object headers, especially beneficial for large-scale applications.
6. Ahead-of-Time (AOT) Method Profiling
Allows profiling methods before runtime, improving performance tuning and startup times.
7. JFR (Java Flight Recorder) Enhancements
New cooperative sampling and method timing/tracing for better observability.
Summary
Java SE 25 focuses on:
- Concurrency improvements (Scoped Values, Structured Concurrency).
- Performance optimizations (Generational Shenandoah, Compact Object Headers).
- Developer productivity (Flexible constructors, compact source files).
- Monitoring & profiling (JFR enhancements, AOT profiling).
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