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.
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SKILL.md
Java Best Practices
Priority: P1 (HIGH)
Implementation Guidelines
- Immutability: Prefer immutable objects (
finalfields, unmodifiable collections). - Access Modifiers: Minimize visibility. Default to package-private (no modifier). Use
privatefor all fields. Onlypublicfor API contracts. - Composition > Inheritance: Favor
Has-AoverIs-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 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::toUpperCaseovers -> s.toUpperCase()where readable.
Anti-Patterns
- No Null Returns: Return Optional 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
Files
3- SKILL.md
01178dcbc91.9 KB - evals/evals.json
f609754e2c3.3 KB - references/example.md
fc8d4adfc52.0 KB
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