Design Patterns for Backend Engineers: Decorator, Command & Adapter Demystified

Design patterns aren’t academic theory—they’re reusable solutions to problems you’ve already faced, whether you realized it or not. If you’ve worked with Spring, Android, game engines, or distributed systems, you’ve encountered them in the wild.

In this article, we’ll demystify three essential design patterns every backend engineer must master:

• Decorator – Add behavior dynamically without subclass explosion

• Command – Encapsulate actions as objects for flexibility and control

• Adapter – Make incompatible systems work together seamlessly

Each section includes practical Java examples, real-world use cases, and guidance for system design interviews.

This article is part of our Design Patterns Series for backend engineers and system designers.