java-design-patterns/lazy-loading/README.md

---
layout: pattern
title: Lazy Loading
folder: lazy-loading
permalink: /patterns/lazy-loading/
categories: Idiom
tags:
 - Performance
---

## Intent
Lazy loading is a design pattern commonly used to defer
initialization of an object until the point at which it is needed. It can
contribute to efficiency in the program's operation if properly and
appropriately used.

## Class diagram
![alt text](./etc/lazy-loading.png "Lazy Loading")

## Applicability
Use the Lazy Loading idiom when

* eager loading is expensive or the object to be loaded might not be needed at all

## Real world examples

* JPA annotations @OneToOne, @OneToMany, @ManyToOne, @ManyToMany and fetch = FetchType.LAZY

## Credits

* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)
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: Lazy Loading`
			`folder: lazy-loading`
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/lazy-loading/`
https://github.com/iluwatar/java-design-patterns-web/issues/8 Update pattern categories and tags 2019-12-13 21:09:28 +02:00			`categories: Idiom`
Categorize and tag all patterns #213 2015-12-28 15:52:44 +02:00			`tags:`
Add performance tag to relevant patterns #213 2015-12-28 16:07:43 +02:00			`- Performance`
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			`## Intent`
			`Lazy loading is a design pattern commonly used to defer`
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			`initialization of an object until the point at which it is needed. It can`
			`contribute to efficiency in the program's operation if properly and`
			`appropriately used.`

#1113 Link uml-reverse-mapper created class diagrams to readme, where needed 2019-12-07 20:01:13 +02:00			`## Class diagram`
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			`![alt text](./etc/lazy-loading.png "Lazy Loading")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Lazy Loading idiom 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
			`* eager loading is expensive or the object to be loaded might not be needed at all`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Real world examples`
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
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* JPA annotations @OneToOne, @OneToMany, @ManyToOne, @ManyToMany and fetch = FetchType.LAZY`
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
Fix some markdown errors 2016-04-16 08:52:16 +03:00			`## Credits`
Fix display error 2016-04-15 08:38:08 +03:00
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			`* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)`