Clean Code

This is a solid reference for making code readable and maintainable. It walks you through DRY, KISS, and YAGNI with side-by-side examples of violations and refactored versions, mostly in Java. The naming conventions section is genuinely helpful, covering everything from why "d" is a terrible variable name to why booleans should start with is/has/can. The function design guidance keeps it practical, like keeping methods small and maintaining a single level of abstraction. Use this when you're refactoring messy code or doing code reviews. It won't teach you advanced patterns, but it will stop you from writing the kind of code that makes your teammates groan.

skills.sh installs: 427
GitHub stars: 771
last updated: Feb 8, 2026

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Install

$ npx -y skills add decebals/claude-code-java --skill clean-code --agent claude-code

Installs into .claude/skills of the current project.

Files

Clean Code Skill

Write readable, maintainable code following Clean Code principles.

When to Use

User says "clean this code" / "refactor" / "improve readability"
Code review focusing on maintainability
Reducing complexity
Improving naming

Core Principles

Principle	Meaning	Violation Sign
DRY	Don't Repeat Yourself	Copy-pasted code blocks
KISS	Keep It Simple, Stupid	Over-engineered solutions
YAGNI	You Aren't Gonna Need It	Features "just in case"

DRY - Don't Repeat Yourself

"Every piece of knowledge must have a single, unambiguous representation in the system."

Violation

// ❌ BAD: Same validation logic repeated
public class UserController {

    public void createUser(UserRequest request) {
        if (request.getEmail() == null || request.getEmail().isBlank()) {
            throw new ValidationException("Email is required");
        }
        if (!request.getEmail().contains("@")) {
            throw new ValidationException("Invalid email format");
        }
        // ... create user
    }

SKILL.md on GitHub