Agent-Skills.md

Agent Skills: Java Best Practices

Apply core Effective Java patterns for robust, maintainable code. Use when applying SOLID principles, choosing between inheritance and composition, refactoring Java code smells, or reviewing class design. (triggers: **/*.java, refactor, SOLID, builder, factory, composition, immutable, Optional, checked exception, clean code)

UncategorizedID: hoangnguyen0403/agent-skills-standard/java-best-practices

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hoangnguyen0403/agent-skills-standard
HoangNguyen0403License: Apache-2.0
362103

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Skill Metadata

Name
java-best-practices
Description
"Apply core Effective Java patterns for robust, maintainable code. Use when applying SOLID principles, choosing between inheritance and composition, refactoring Java code smells, or reviewing class design. (triggers: **/*.java, refactor, SOLID, builder, factory, composition, immutable, Optional, checked exception, clean code)"

Java Best Practices

Priority: P1 (HIGH)

Core engineering principles for robust, maintainable Java systems.

Implementation Guidelines

  • Immutability: Prefer immutable objects (final fields, unmodifiable collections).
  • Access Modifiers: Minimize visibility. Default to package-private (no modifier). Use private for all fields. Only public for API contracts.
  • Composition > Inheritance: Favor Has-A over Is-A. Avoid deep hierarchies.
  • Constructors: Use Static Factory Methods (User.of()) over complex constructors.
  • Builder Pattern: Use for objects with 4+ parameters.
  • Exceptions: Recoverable → Checked; Programming error → Unchecked.
  • Fail Fast: Validate parameters (Objects.requireNonNull) at the method start.
  • Interfaces: Code to interfaces (List, Map), not implementations (ArrayList).
  • Dependency Injection: Inject dependencies via constructor; don't create them internally.
  • Method References: Use String::toUpperCase over s -> s.toUpperCase() where readable.

Anti-Patterns

  • No Null Returns: Return Optional<T> or empty collection instead.
  • No Empty Catch: Log or rethrow; never swallow exceptions silently.
  • No God Class: Split into focused classes following Single Responsibility Principle.
  • No Magic Numbers: Extract named constants with clear meaning.
  • No Mutable Statics: Avoid public static mutable fields (global state).

References