java-design-patterns/specification/README.md

---
layout: pattern
title: Specification
folder: specification
permalink: /patterns/specification/
categories: Behavioral
tags:
 - Java
 - Difficulty-Beginner
---

## Also known as
Filter, Criteria

## Intent
Specification pattern separates the statement of how to match a
candidate, from the candidate object that it is matched against. As well as its
usefulness in selection, it is also valuable for validation and for building to
order

![alt text](./etc/specification.png "Specification")

## Applicability
Use the Specification pattern when

* you need to select a subset of objects based on some criteria, and to refresh the selection at various times
* you need to check that only suitable objects are used for a certain role (validation)

## Related patterns

* Repository

## Credits

* [Martin Fowler - Specifications](http://martinfowler.com/apsupp/spec.pdf)
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: Specification`
			`folder: specification`
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/specification/`
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`
Categorize and tag all patterns #213 2015-12-28 15:52:44 +02:00			`tags:`
			`- Java`
			`- Difficulty-Beginner`
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			`---`

Add aliases for Specification pattern 2016-07-07 08:46:56 +03:00			`## Also known as`
			`Filter, Criteria`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Intent`
			`Specification pattern separates the statement of how to match a`
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			`candidate, from the candidate object that it is matched against. As well as its`
			`usefulness in selection, it is also valuable for validation and for building to`
			`order`

			`![alt text](./etc/specification.png "Specification")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Specification pattern when`
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
			`* you need to select a subset of objects based on some criteria, and to refresh the selection at various times`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* you need to check that only suitable objects are used for a certain role (validation)`
Work on #226, moved pattern specific credits to respective pattern pages in website 2015-09-03 18:17:07 +05:30
Adjust pattern categories and tags 2016-07-21 09:27:48 +03:00			`## Related patterns`

			`* Repository`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Credits`
Work on #226, moved pattern specific credits to respective pattern pages in website 2015-09-03 18:17:07 +05:30
			`* [Martin Fowler - Specifications](http://martinfowler.com/apsupp/spec.pdf)`