Structural: Adapter, Decorator, Proxy, Facade

A Proxy is a same-interface stand-in that controls access to the real object and can add lazy creation, security, caching, or remote calls around it.

Adapter converts, Decorator wraps to add, Composite forms trees, Proxy controls access, Facade simplifies, Bridge splits abstraction from implementation, and Flyweight shares to save memory.

Each Java stream decorator wraps another stream of the same type and adds one feature, so you stack capabilities at runtime instead of building a subclass for every combination.

Facade gives one simple front door to a complex subsystem; Adapter translates one incompatible interface into the one the client expects.

The Adapter pattern translates a foreign interface into the one your code expects, so incompatible classes collaborate without coupling.

The Decorator pattern wraps an object to add behaviour dynamically, stacking features without an explosion of subclasses.