all index.md files renamed to README.md for more compatibility with github

decorator/README.md

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+---
+layout: pattern
+title: Decorator
+folder: decorator
+permalink: /patterns/decorator/
+categories: Structural
+tags:
+ - Java
+ - Gang Of Four
+ - Difficulty-Beginner
+---
+
+## Also known as
+Wrapper
+
+## Intent
+Attach additional responsibilities to an object dynamically.
+Decorators provide a flexible alternative to subclassing for extending
+functionality.
+
+![alt text](./etc/decorator.png "Decorator")
+
+## 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+* for responsibilities that can be withdrawn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
+
+## Credits
+
+* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
+* [Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions](http://www.amazon.com/Functional-Programming-Java-Harnessing-Expressions/dp/1937785467/ref=sr_1_1)
+* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)