In software design patterns, what is the adapter pattern?

• A. A pattern that allows incompatible interfaces to work together by wrapping an adapter
• B. A pattern to decompose tasks into microservices
• C. A pattern for event-driven architecture
• D. A pattern for database sharding

Answer: (A)

The adapter pattern creates a compatibility layer between two interfaces so they can work together. It does this by introducing a wrapper—the adapter—that sits between the client and the existing component (the adaptee). The adapter exposes the interface the client expects and translates the client’s calls into the specific methods the adaptee provides, possibly converting data formats along the way. This lets you reuse legacy code or integrate a third‑party library without changing either side. For example, if a client wants a simple draw() method but the library offers a complex API with different method names, an adapter can implement draw() and internally call the appropriate library methods, translating parameters as needed. This approach is about making mismatched interfaces cooperate, not about how to structure a system into microservices, how components communicate via events, or how to shard a database.