# Java Best Practices

> Use this skill when generating or reviewing Java code to ensure readability, maintainability, correctness, and modern best practices.

- Skill: `senoritadeveloper01/java-best-practices` (Agent Skill)
- Install (CLI): `npx skillmds@latest add senoritadeveloper01/java-best-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/senoritadeveloper01/java-best-practices/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: senoritadeveloper01 (https://skillmd.com/u/senoritadeveloper01)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/senoritadeveloper01/java-best-practices

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# Java Best Practices

## Scope
Apply this skill when working on:
- service and domain logic
- utility classes
- refactoring existing code
- general Java design and structure

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## Code clarity and readability
- Use intention-revealing names for classes, methods, and variables.
- Keep methods small and focused on a single responsibility.
- Avoid deep nesting; prefer early returns.
- Prefer readability over clever or overly compact code.

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## Null safety
- Avoid NullPointerException risks in chained calls.
- Prefer Optional for nullable return values.
- Return empty collections instead of null.
- Validate inputs explicitly.

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## Exception handling
- Do not swallow exceptions.
- Avoid catching overly broad exceptions (Exception, Throwable).
- Always preserve the original cause when rethrowing.
- Log with context and stack trace.

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## Separation of concerns
- Keep business logic separate from persistence and transport layers.
- Avoid large “god classes”.
- Keep classes cohesive and focused.

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## Collections and streams
- Do not modify collections while iterating.
- Use streams for transformations, loops for side effects.
- Avoid unnecessary stream usage in tight loops.
- Be explicit about mutability when collecting results.

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## Dependency and design principles
- Prefer constructor injection.
- Make dependencies explicit.
- Avoid hidden or implicit dependencies.
- Design classes for clarity and testability.

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## Resource management
- Use try-with-resources for AutoCloseable resources.
- Ensure all I/O and database resources are properly closed.

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## Concurrency awareness
- Avoid shared mutable state when possible.
- Use thread-safe collections when needed.
- Prefer immutable objects.
- Be careful with async and multi-threaded code.

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## Performance awareness
- Avoid obvious performance anti-patterns:
    - string concatenation in loops
    - repeated regex compilation
    - unnecessary object creation in hot paths
- Prefer readability first; optimize only when necessary.
- Measure before optimizing.

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## Refactoring mindset
- Refactor when duplication appears.
- Simplify complex logic into smaller units.
- Improve naming and structure when readability suffers.
- Prefer incremental improvements.

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## Testability
- Write code that is easy to test.
- Avoid tight coupling.
- Keep business logic independent from frameworks when possible.
- Prefer deterministic behavior.

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## Output expectations
When generating or refactoring code:
- prioritize clarity and maintainability
- avoid unnecessary abstraction
- follow modern Java idioms
- improve existing code where possible
- explain non-obvious improvements briefly