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Decorator

Difficulty-Beginner Gang Of Four Java Structural

Also known as

Wrapper

Intent

Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.

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Applicability

Use Decorator

  • To add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects
  • For responsibilities that can be withdrawn
  • When extension by subclassing is impractical. Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing

Real world examples

Credits