java-design-patterns/double-dispatch/README.md

---
title: Double Dispatch
category: Idiom
language: en
tags:
 - Extensibility
---

## Intent
Double Dispatch pattern is a way to create maintainable dynamic
behavior based on receiver and parameter types.

## Class diagram
![alt text](./etc/double-dispatch.png "Double Dispatch")

## Applicability
Use the Double Dispatch pattern when

* the dynamic behavior is not defined only based on receiving object's type but also on the receiving method's parameter type.

## Real world examples

* [ObjectOutputStream](https://docs.oracle.com/javase/8/docs/api/java/io/ObjectOutputStream.html)
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			`---`
			`title: Double Dispatch`
Update frontmatters 2021-09-12 13:27:23 +03:00			`category: Idiom`
fix: Fixed pages showing up in wrong language (#1752) * Fix languages * Missed change for version number * Add language field for presentation * Revert change in README for double buffer Co-authored-by: Jackie Nim <=> 2021-05-19 10:49:05 -06:00			`language: en`
Categorize and tag all patterns #213 2015-12-28 15:52:44 +02:00			`tags:`
https://github.com/iluwatar/java-design-patterns-web/issues/8 Update pattern categories and tags 2019-12-13 21:09:28 +02:00			`- Extensibility`
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`
			`Double Dispatch pattern is a way to create maintainable dynamic`
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			`behavior based on receiver and parameter types.`

#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/double-dispatch.png "Double Dispatch")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Double Dispatch 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
			`* the dynamic behavior is not defined only based on receiving object's type but also on the receiving method's parameter type.`

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			`* [ObjectOutputStream](https://docs.oracle.com/javase/8/docs/api/java/io/ObjectOutputStream.html)`