Decorator is the structural pattern for optional layered behavior.
In Java, it is one of the most practical structural patterns because real systems often need to wrap an object with logging, buffering, metrics, security checks, caching, or formatting without changing the wrapped object’s core contract.
The pattern works best when the wrapped interface is small and stable. It works poorly when decorators become mini-frameworks that obscure call order and side effects.
In this section
- Implementing Decorator Pattern in Java
Implement Java decorators by wrapping a small interface, delegating cleanly, and keeping each added behavior narrow and explicit.
- Interface-Based Decorators
Keep Java decorators practical by decorating narrow interfaces rather than large concrete types with sprawling method surfaces.
- Chaining Decorators
Chain Java decorators deliberately, because wrapper order changes behavior, visibility, performance, and failure semantics.
- Decorator vs. Inheritance
Compare Decorator with inheritance in Java and choose the one that matches variation shape, optional behavior, and runtime composition needs.
- Decorator Pattern Use Cases and Examples in Java
See where Decorator genuinely helps in Java, from I/O wrappers and handlers to logging, metrics, caching, and authorization layers.