121-java-object-oriented-design
Java Object-Oriented Design Guidelines
Review and improve Java code using comprehensive object-oriented design guidelines and refactoring practices.
What is covered in this Skill?
- Fundamental design principles (SOLID, DRY, YAGNI)
- Class and interface design: composition over inheritance, immutability, accessibility minimization, accessor methods
- Core OOP concepts: encapsulation, inheritance, polymorphism
- Object creation patterns: static factory methods, Builder, Singleton, dependency injection, avoiding unnecessary objects
- OOD code smells: God Class, Feature Envy, Inappropriate Intimacy, Refused Bequest, Shotgun Surgery, Data Clumps
- Method design: parameter validation, defensive copies, careful signatures, empty collections over nulls, Optional usage
- Exception handling: checked vs. runtime exceptions, standard exceptions, failure-capture messages, no silent ignoring
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 OOD changes, ensure the project compiles. If compilation fails, stop immediately — do not proceed until resolved. After applying improvements, run full verification.
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