java-design-patterns/adapter/index.md

---
layout: pattern
title: Adapter
folder: adapter
permalink: /patterns/adapter/
categories: Structural
tags:
 - Java
 - Gang Of Four
 - Difficulty-Beginner
---

**Also known as:** Wrapper

**Intent:** Convert the interface of a class into another interface the clients
expect. Adapter lets classes work together that couldn't otherwise because of
incompatible interfaces.

![alt text](./etc/adapter.png "Adapter")

**Applicability:** Use the Adapter pattern when

* you want to use an existing class, and its interface does not match the one you need
* you want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
* you need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.

**Real world examples:**

* [java.util.Arrays#asList()](http://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#asList%28T...%29)

**Credits**

* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)