122 Java Type Design

This one walks through your Java code looking for type design problems like primitive obsession, weak type hierarchies, and inconsistent naming. It pushes you toward value objects (EmailAddress instead of String, Money instead of double), generic type parameters, and fluent interfaces. The workflow is cautious: it compiles before touching anything, applies refactorings based on pattern examples in the reference doc, then runs clean verify. Good for codebases that work but feel mushy around the edges, where you're passing strings and primitives everywhere instead of domain types. It's opinionated about BigDecimal for money and won't proceed if your project doesn't compile first.

skills.sh installs: 132
GitHub stars: 393
last updated: Jun 3, 2026

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$ npx -y skills add jabrena/cursor-rules-java --skill 122-java-type-design --agent claude-code

Installs into .claude/skills of the current project.

Files

Type Design Thinking in Java

Review and improve Java code using comprehensive type design principles that apply typography concepts to code structure and organization for maximum clarity and maintainability.

What is covered in this Skill?

Clear type hierarchies: nested static classes, logical structure
Consistent naming conventions: domain-driven patterns, uniform interface/implementation naming
Strategic whitespace for readability
Type-safe wrappers: value objects replacing primitive obsession (EmailAddress, Money)
Generic type parameters: flexible reusable types, bounded parameters
Domain-specific fluent interfaces: builder pattern, method chaining
Type weights: conceptual importance — core domain vs supporting vs utility
Type contrast through interfaces: contract vs implementation separation
Aligned method signatures: consistent parameter and return types across related classes
Self-documenting code: clear descriptive names
BigDecimal for precision-sensitive calculations (financial/monetary operations)
Strategic type selection: Optional, Set vs List, interfaces over concrete types