java-design-patterns/strategy/README.md

---
layout: pattern
title: Strategy
folder: strategy
permalink: /patterns/strategy/
categories: Behavioral
tags:
 - Java
 - Difficulty-Beginner
 - Gang Of Four
---

## Also known as
Policy

## Intent
Define a family of algorithms, encapsulate each one, and make them
interchangeable. Strategy lets the algorithm vary independently from clients
that use it.

![alt text](./etc/strategy_1.png "Strategy")

## Applicability
Use the Strategy pattern when

* many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors
* you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms
* an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures
* a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class

## Tutorial 
* [Strategy Pattern Tutorial](https://www.journaldev.com/1754/strategy-design-pattern-in-java-example-tutorial)

## Credits

* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)
* [Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions](http://www.amazon.com/Functional-Programming-Java-Harnessing-Expressions/dp/1937785467/ref=sr_1_1)
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: Strategy`
			`folder: strategy`
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/strategy/`
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`
			`- Difficulty-Beginner`
			`- Gang Of Four`
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			`---`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Also known as`
			`Policy`
Added alias names for GOF patterns #267 2015-11-04 21:13:32 +02:00
Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Intent`
			`Define a family of algorithms, encapsulate each one, and make them`
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			`interchangeable. Strategy lets the algorithm vary independently from clients`
			`that use it.`

			`![alt text](./etc/strategy_1.png "Strategy")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Strategy 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
			`* many related classes differ only in their behavior. Strategies provide a way to configure a class either one of many behaviors`
			`* you need different variants of an algorithm. for example, you might define algorithms reflecting different space/time trade-offs. Strategies can be used when these variants are implemented as a class hierarchy of algorithms`
			`* an algorithm uses data that clients shouldn't know about. Use the Strategy pattern to avoid exposing complex, algorithm-specific data structures`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* a class defines many behaviors, and these appear as multiple conditional statements in its operations. Instead of many conditionals, move related conditional branches into their own Strategy class`
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
added tutorial links to bridge, decorator, abstract-factory, strategy and template method patterns 2017-09-23 20:55:38 -04:00			`## Tutorial`
			`* [Strategy Pattern Tutorial](https://www.journaldev.com/1754/strategy-design-pattern-in-java-example-tutorial)`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Credits`
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
			`* [Design Patterns: Elements of Reusable Object-Oriented Software](http://www.amazon.com/Design-Patterns-Elements-Reusable-Object-Oriented/dp/0201633612)`
Work on #226, moved pattern specific references to respective patterns. And removed credits section from Home page. 2016-01-27 12:55:59 +05:30			`* [Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions](http://www.amazon.com/Functional-Programming-Java-Harnessing-Expressions/dp/1937785467/ref=sr_1_1)`