What problem does it solve? Choosing and correctly applying design patterns in Java is hard because many patterns share identical UML structures while differing in intent. This Skill provides a structured knowledge base from Vaskaran Sarcar's "Java Design Patterns, 2nd Edition" covering all 23 GoF patterns plus Simple Factory, Null Object, and MVC, so you can pick the right pattern, understand trade-offs, and avoid antipatterns. ## Core Features & Use Cases - Pattern Reference by Chapter: Load any of 29 chapter files covering intent, participants, implementation variants, and Q&A-driven trade-off analysis for each pattern. - Confused-Pair Comparisons: Get intent-based distinctions for commonly mixed-up pairs like Proxy vs Decorator, State vs Strategy, and Adapter vs Bridge via the FAQ chapter. - Decision Support: Use the cheatsheet's decision tree, threshold rules (e.g., 4+ constructor params suggests Builder), Java built-in examples, and antipattern red flags. - Use Case: When refactoring a class with growing if-else chains on object state, ask about the State pattern to get its structure, transition ownership guidance, and a comparison with Strategy before rewriting the code. ## Quick Start Ask the agent to explain the difference between the Proxy and Decorator patterns with a Java example using this design patterns skill.
