Use when you need to review, improve, or refactor Java code for type design quality — including establishing clear type hierarchies, applying consistent naming conventions, eliminating primitive obsession with domain-specific value objects, leveraging generic type parameters, creating type-safe wrappers, designing fluent interfaces, ensuring precision-appropriate numeric types (BigDecimal for financial calculations), and improving type contrast through interfaces and method signature alignment.…
Use when you need to review, improve, or refactor Java code for type design quality — including establishing clear type hierarchies, applying consistent naming conventions, eliminating primitive obsession with domain-specific value objects, leveraging generic type parameters, creating type-safe wrappers, designing fluent interfaces, ensuring precision-appropriate numeric types (BigDecimal for financial calculations), and improving type contrast through interfaces and method signature alignment.
This should trigger for requests such as Review Java code for type design; Improve type design in Java code; Fix primitive obsession in Java code; Create value objects in Java code.
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Version0.18.0
LicenseApache-2.0
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author
Juan Antonio Breña Moral
version
0.18.0
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skill mdSKILL.md3,917 B
docsSUMMARY.md731 B
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SKILL.md
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
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
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Constraints
Before applying any type design changes, ensure the project compiles. If compilation fails, stop immediately — do not proceed until resolved. After applying improvements, run full verification.
MANDATORY: Run ./mvnw compile or mvn compile before applying any change
SAFETY: If compilation fails, stop immediately and do not proceed — compilation failure is a blocking condition
VERIFY: Run ./mvnw clean verify or mvn clean verify after applying improvements
BEFORE APPLYING: Read the reference for detailed examples, good/bad patterns, and constraints
EDGE CASE: If request scope is ambiguous, stop and ask a clarifying question before applying changes
EDGE CASE: If required inputs, files, or tooling are missing, report what is missing and ask whether to proceed with setup guidance
When to use this skill
Review Java code for type design
Improve type design in Java code
Fix primitive obsession in Java code
Create value objects in Java code
Create type hierarchies in Java code
Create fluent interfaces in Java code
Workflow
Compile project before type-design changes
Run ./mvnw compile or mvn compile and stop immediately if compilation fails.
Read type-design reference and inspect code
Read references/122-java-type-design.md and identify type hierarchy, naming, and value-object improvements.
Apply type-design refactorings
Implement selected type-safety and readability improvements based on applicable patterns.
Verify with full build
Run ./mvnw clean verify or mvn clean verify after applying improvements.
Reference
For detailed guidance, examples, and constraints, see [references/122-java-type-design.md](references/122-java-type-design.md).
