java-design-patterns/monostate/README.md

---
layout: pattern
title: MonoState
folder: monostate
permalink: /patterns/monostate/
categories: Creational
tags:
 - Java
 - Difficulty-Beginner
---

## Also known as
Borg

## Intent
Enforces a behaviour like sharing the same state amongst all instances.

![alt text](./etc/monostate.png "MonoState")

## Applicability
Use the Monostate pattern when

* The same state must be shared across all instances of a class.
* Typically this pattern might be used everywhere a Singleton might be used. Singleton usage however is not transparent, Monostate usage is.
* Monostate has one major advantage over singleton. The subclasses might decorate the shared state as they wish and hence can provide dynamically different behaviour than the base class.

## Typical Use Case

* the logging class
* managing a connection to a database
* file manager

## Real world examples

Yet to see this.
Monostate pattern #85 2015-10-04 03:06:11 +05:30			`---`
			`layout: pattern`
			`title: MonoState`
			`folder: monostate`
			`permalink: /patterns/monostate/`
			`categories: Creational`
Categorize and tag all patterns #213 2015-12-28 15:52:44 +02:00			`tags:`
			`- Java`
			`- Difficulty-Beginner`
Monostate pattern #85 2015-10-04 03:06:11 +05:30			`---`

#459 added known aliast for monostate pattern 2016-07-26 20:33:43 +02:00			`## Also known as`
			`Borg`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Intent`
			`Enforces a behaviour like sharing the same state amongst all instances.`
Monostate pattern #85 2015-10-04 03:06:11 +05:30
			`![alt text](./etc/monostate.png "MonoState")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Monostate pattern when`
Monostate pattern #85 2015-10-04 03:06:11 +05:30
			`* The same state must be shared across all instances of a class.`
Made changes according to feedback issue #258 2015-10-09 23:20:58 +05:30			`* Typically this pattern might be used everywhere a Singleton might be used. Singleton usage however is not transparent, Monostate usage is.`
Monostate pattern #85 2015-10-04 03:06:11 +05:30			`* Monostate has one major advantage over singleton. The subclasses might decorate the shared state as they wish and hence can provide dynamically different behaviour than the base class.`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Typical Use Case`
Monostate pattern #85 2015-10-04 03:06:11 +05:30
			`* the logging class`
			`* managing a connection to a database`
			`* file manager`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Real world examples`
Monostate pattern #85 2015-10-04 03:06:11 +05:30
			`Yet to see this.`