Agent skill

java-expert

Expert knowledge of Java 25 features including virtual threads, pattern matching, records, sealed classes, value types, and Project Loom/Valhalla features. Use when the user asks about Java programming, Java 25 features, concurrency, performance optimization, or modern Java idioms.

View SKILL.md on GitHub Repository
Stars 15
Forks 7

Install this agent skill to your Project

npx add-skill https://github.com/diegopacheco/ai-playground/tree/main/pocs/java-25-spring-boot-4-spring-ai-skills/src/main/resources/.claude/skills/java-expert

SKILL.md

Java 25 Expert Skill

Overview

Provides expert guidance on Java 25 language features and best practices.

Key Java 25 Features

Virtual Threads (Project Loom)

  • Use Thread.ofVirtual().start(runnable) for lightweight concurrency
  • Virtual threads are ideal for I/O-bound workloads
  • Use Executors.newVirtualThreadPerTaskExecutor() for thread pools

Pattern Matching

  • Switch expressions with pattern matching
  • Deconstruction patterns for records
  • Guarded patterns with when clauses

Records

  • Immutable data carriers with auto-generated constructors, equals, hashCode, toString
  • Custom compact constructors for validation

Sealed Classes

  • Restrict class hierarchies with sealed, permits
  • Enable exhaustive pattern matching

String Templates (Preview)

  • Template processors like STR."\{value}"
  • Custom template processors

Best Practices

  • Prefer records over plain POJOs for data transfer
  • Use sealed interfaces for algebraic data types
  • Leverage virtual threads for high-throughput servers
  • Use pattern matching to eliminate instanceof casts

Examples

java
record Point(int x, int y) {}

sealed interface Shape permits Circle, Rectangle {}
record Circle(Point center, double radius) implements Shape {}
record Rectangle(Point topLeft, Point bottomRight) implements Shape {}

String describe(Shape shape) {
    return switch (shape) {
        case Circle c when c.radius() > 10 -> "Large circle";
        case Circle c -> "Small circle";
        case Rectangle r -> "Rectangle";
    };
}

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