java-design-patterns/memento/index.md

---
layout: pattern
title: Memento
folder: memento
permalink: /patterns/memento/
categories: Behavioral
tags:
 - Java
 - Gang Of Four
---

**Intent:** Without violating encapsulation, capture and externalize an
object's internal state so that the object can be restored to this state later.

![alt text](./etc/memento.png "Memento")

**Applicability:** Use the Memento pattern when

* a snapshot of an object's state must be saved so that it can be restored to that state later, and
* a direct interface to obtaining the state would expose implementation details and break the object's encapsulation

**Real world examples:**

* [java.util.Date](http://docs.oracle.com/javase/8/docs/api/java/util/Date.html)

**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: Memento`
			`folder: memento`
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/memento/`
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`
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: Without violating encapsulation, capture and externalize an`
			`object's internal state so that the object can be restored to this state later.`

			`![alt text](./etc/memento.png "Memento")`

			`Applicability: Use the Memento pattern when`

			`* a snapshot of an object's state must be saved so that it can be restored to that state later, and`
			`* a direct interface to obtaining the state would expose implementation details and break the object's encapsulation`

			`Real world examples:`

Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* [java.util.Date](http://docs.oracle.com/javase/8/docs/api/java/util/Date.html)`
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)`