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https://github.com/iluwatar/java-design-patterns-web/issues/8 Update pattern categories and tags

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Ilkka Seppälä
2019-12-13 21:09:28 +02:00
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observer/README.md
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@ -5,8 +5,6 @@ folder: observer
permalink: /patterns/observer/
categories: Behavioral
tags:
- Java
- Difficulty-Beginner
- Gang Of Four
- Reactive
---
@ -25,13 +23,13 @@ automatically.
## Applicability
Use the Observer pattern in any of the following situations
* when an abstraction has two aspects, one dependent on the other. Encapsulating these aspects in separate objects lets you vary and reuse them independently
* when a change to one object requires changing others, and you don't know how many objects need to be changed
* when an object should be able to notify other objects without making assumptions about who these objects are. In other words, you don't want these objects tightly coupled
* When an abstraction has two aspects, one dependent on the other. Encapsulating these aspects in separate objects lets you vary and reuse them independently
* When a change to one object requires changing others, and you don't know how many objects need to be changed
* When an object should be able to notify other objects without making assumptions about who these objects are. In other words, you don't want these objects tightly coupled
## Typical Use Case
* changing in one object leads to a change in other objects
* Changing in one object leads to a change in other objects
## Real world examples