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.

Prerequisites: Run ./mvnw compile or mvn compile before applying any change. If compilation fails, stop immediately and do not proceed — compilation failure is a blocking condition.

Core areas: 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 assignment — 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), and strategic type selection (Optional, Set vs List, interfaces over concrete types).

Scope: The reference is organized by examples (with good/bad code patterns) for each core area. Apply recommendations based on applicable examples; validate compilation before changes and run ./mvnw clean verify or mvn clean verify after applying improvements.

Before applying changes: Read the reference for detailed examples, good/bad patterns, and constraints.

Reference

For detailed guidance, examples, and constraints, see references/122-java-type-design.md.