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

dependency-injection/README.md

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+---
+layout: pattern
+title: Dependency Injection
+folder: dependency-injection
+permalink: /patterns/dependency-injection/
+categories: Behavioral
+tags:
+ - Java
+ - Difficulty-Beginner
+---
+
+## Intent
+Dependency Injection is a software design pattern in which one or
+more dependencies (or services) are injected, or passed by reference, into a
+dependent object (or client) and are made part of the client's state. The
+pattern separates the creation of a client's dependencies from its own
+behavior, which allows program designs to be loosely coupled and to follow the
+inversion of control and single responsibility principles.
+
+![alt text](./etc/dependency-injection.png "Dependency Injection")
+
+## Applicability
+Use the Dependency Injection pattern when
+
+* when you need to remove knowledge of concrete implementation from object
+* to enable unit testing of classes in isolation using mock objects or stubs