---
title: "What are Observer and Observable ?"  
description: "What are Observer and Observable ?"  
author: "Anonymous User"  
published: 2015-07-29  
updated: 2020-09-19  
canonical: https://www.mindstick.com/interview/2740/what-are-observer-and-observable  
category: "java"  
tags: ["java"]  
reading_time: 1 minute  

---

# What are Observer and Observable ?

Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.

## Answers

### Answer by Anonymous User

Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.


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Original Source: https://www.mindstick.com/interview/2740/what-are-observer-and-observable

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