Java 25 (LTS)

Java 25 is a Long-Term Support release introducing improvements in concurrency, pattern matching, and JVM performance. These short notes help developers quickly revise important concepts.

1. Primitive Types in Pattern Matching

Java 25 allows primitive types to be used directly in pattern matching.

int number = 10;

switch (number) {
    case int n when n > 5 -> System.out.println("Greater than 5");
    default -> System.out.println("Small number");
}

2. Scoped Values

Scoped values allow safe sharing of immutable data between threads.

static final ScopedValue USER = ScopedValue.newInstance();

ScopedValue.where(USER, "Admin").run(() -> {
    System.out.println(USER.get());
});

3. Structured Concurrency

Structured concurrency treats multiple parallel tasks as a single logical unit.

try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {

    Future user = scope.fork(() -> getUser());
    Future orders = scope.fork(() -> getOrders());

    scope.join();
    scope.throwIfFailed();

    System.out.println(user.resultNow());
}

4. Virtual Thread Improvements

Virtual threads allow applications to run millions of lightweight threads efficiently.

Thread.startVirtualThread(() -> {
    System.out.println("Running in virtual thread");
});

5. Class-File API

Java 25 introduces a modern API for reading and generating Java class files.

ClassFile classFile = ClassFile.of();
byte[] bytes = classFile.build();

Quick Revision Summary