java-design-patterns/mediator/index.md

---
layout: pattern
title: Mediator
folder: mediator
permalink: /patterns/mediator/
categories: Behavioral
tags:
 - Java
 - Gang Of Four
 - Difficulty-Intermediate
---

**Intent:** Define an object that encapsulates how a set of objects interact.
Mediator promotes loose coupling by keeping objects from referring to each
other explicitly, and it lets you vary their interaction independently.

![alt text](./etc/mediator_1.png "Mediator")

**Applicability:** Use the Mediator pattern when

* a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand
* reusing an object is difficult because it refers to and communicates with many other objects
* a behavior that's distributed between several classes should be customizable without a lot of subclassing

**Credits**

* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00			`---`
			`layout: pattern`
			`title: Mediator`
			`folder: mediator`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`permalink: /patterns/mediator/`
Work on #213 - properly categorize all patterns - remove pattern list from readme - minor fixes to readme - removed "introduction" because its not a pattern and an error i committed some time ago 2015-08-20 21:40:07 +02:00			`categories: Behavioral`
Work on #226, #213, added references of Gang Of Four to all GoF patterns, added tag for Gang Of Four, added difficulty tags to some of them 2015-09-22 18:25:56 +05:30			`tags:`
			`- Java`
			`- Gang Of Four`
			`- Difficulty-Intermediate`
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00			`---`

			`Intent: Define an object that encapsulates how a set of objects interact.`
			`Mediator promotes loose coupling by keeping objects from referring to each`
			`other explicitly, and it lets you vary their interaction independently.`

			`![alt text](./etc/mediator_1.png "Mediator")`

			`Applicability: Use the Mediator pattern when`

			`* a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand`
			`* reusing an object is difficult because it refers to and communicates with many other objects`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* a behavior that's distributed between several classes should be customizable without a lot of subclassing`
Work on #226, #213, added references of Gang Of Four to all GoF patterns, added tag for Gang Of Four, added difficulty tags to some of them 2015-09-22 18:25:56 +05:30
			`Credits`

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