How do I install the 121 Java Object Oriented Design skill?

Run npx skillmds add majiayu000/121-java-object-oriented-design-2 in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is 121 Java Object Oriented Design free to use?

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Who published 121 Java Object Oriented Design?

majiayu000 (@majiayu000) published this skill. Their other Agent Skills are listed on their SkillMD profile.

121 Java Object Oriented Design by majiayu000

Name: 121 Java Object Oriented Design
Rating: 4.2 (5 reviews)
Author: majiayu000

121 Java Object Oriented Design

Use when you need to review, improve, or refactor Java code for object-oriented design quality — including applying SOLID, DRY, and YAGNI principles, improving class and interface design, fixing OOP concept misuse (encapsulation, inheritance, polymorphism), identifying and resolving code smells (God Class, Feature Envy, Data Clumps), or improving object creation patterns, method design, and exception handling.

majiayu000 2d41952 2 files · 3.0 KB Updated Sep 9, 2026 567 repo stars

File contents

Java Object-Oriented Design Guidelines

Review and improve Java code using comprehensive object-oriented design guidelines and refactoring practices.

Core areas: 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 pattern, 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), and exception handling (checked vs. runtime exceptions, standard exceptions, failure-capture messages, no silent ignoring).

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.

Multi-step scope: Step 1 validates the project compiles. Step 2 identifies applicable design principles and code smells. Step 3 applies SOLID/DRY/YAGNI improvements. Step 4 addresses class and interface design issues. Step 5 resolves OOP misuse and code smells. Step 6 improves object creation, method design, and exception handling patterns.

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

Reference

For detailed guidance, examples, and constraints, see references/121-java-object-oriented-design.md.

---name: 121-java-object-oriented-design-2description: Use when you need to review, improve, or refactor Java code for object-oriented design quality — including applying SOLID, DRY, and YAGNI principles, improving class and interface design, fixing OOP concept misuse (encapsulation, inheritance, polymorphism), identifying and resolving code smells (God Class, Feature Envy, Data Clumps), or improving object creation patterns, method design, and exception handling.---# Java Object-Oriented Design Guidelines Review and improve Java code using comprehensive object-oriented design guidelines and refactoring practices. **Core areas:** 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 pattern, 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), and exception handling (checked vs. runtime exceptions, standard exceptions, failure-capture messages, no silent ignoring). **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. **Multi-step scope:** Step 1 validates the project compiles. Step 2 identifies applicable design principles and code smells. Step 3 applies SOLID/DRY/YAGNI improvements. Step 4 addresses class and interface design issues. Step 5 resolves OOP misuse and code smells. Step 6 improves object creation, method design, and exception handling patterns. **Before applying changes:** Read the reference for detailed examples, good/bad patterns, and constraints. ## Reference For detailed guidance, examples, and constraints, see [references/121-java-object-oriented-design.md](references/121-java-object-oriented-design.md).

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