Structural Design Patterns Scenario Quiz

Q1. You are designing a menu system for an application where a menu can contain menu items as well as sub-menus. A single call like display() or enable() should work uniformly on both. Which design pattern would you use?



Q2. You need to wrap a third-party logging library that has an incompatible interface so it matches your codebase’s logger interface. Which design pattern is most suitable?



Q3. In a home-automation system, a single MovieNightMode.startMovieNight() method internally dims lights, lowers blinds, turns on TV/audio, and adjusts the thermostat. Which design pattern does this illustrate?



Q4. GUI windows can gain features like borders, scroll bars, or shadows at runtime by wrapping them in other objects that add behavior. Which design pattern enables this?



Q5. You want to decouple shape classes (Circle, Square) from rendering back-ends (SVG, OpenGL) so either side can vary independently. Which structural pattern achieves this?



Q6. A text editor reuses shared glyph objects (font, size) for thousands of characters while storing each character’s position separately to save memory. Which pattern is this?



Q7. A CachingFetcher object checks permissions and caches results before delegating to a costly DocumentFetcher service. Which design pattern does CachingFetcher represent?



Q8. For each external payment gateway, you implement a class that converts the common PaymentProcessor interface to that gateway’s API. Which pattern are these classes applying?



Q9. Your data-access layer defines a Database interface and separate MySQLDatabase and PostgreSQLDatabase implementations that can be swapped at runtime. Which design pattern is exemplified?



Q10. Managers contain subordinates and calling getSalary() on a manager aggregates all team salaries, while the same call on an employee returns just their own. Which pattern would you use?



Q11. You wrap a DataService with LoggingService and TimingService objects that implement the same interface and add extra behavior around fetchData(). Which pattern is this?



Q12. A ReportGenerator.generateReport() method hides several steps of a complex analytics library behind one call. Which pattern have you implemented?



Q13. XmlToJsonAdapter implements a JSON-producing interface but internally converts XML data to JSON on the fly. Which design pattern does it embody?



Q14. An ImageProxy delays loading a high-resolution image from disk until display() is called, then delegates to the real image object. Which pattern is ImageProxy using?



Q15. BufferedInputStream and EncryptedInputStream wrap another InputStream and add functionality like buffering or encryption, and wrappers can be stacked. What design pattern are they using?



Q16. A 2-D game shares one sprite per enemy type among hundreds of enemies, each storing only position and health. Which design pattern does this correspond to?



Q17. UI elements hold a reference to a Renderer interface so you can switch between DirectXRenderer and OpenGLRenderer at runtime without changing UI classes. Which pattern allows this flexibility?



Q18. A SystemFacade wraps low-level file, network, and graphics APIs so the rest of the code calls SystemFacade methods instead of the underlying libraries. Which pattern does this demonstrate?



Q19. A calculator builds an expression tree where each node has evaluate(); numbers return a value, operations evaluate children and combine results. Which pattern is at work?



Q20. RemoteServiceProxy implements the same methods as a remote service but handles network communication transparently so callers treat it as a local object. What pattern is used?



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