# Uses of Interface
java.util.Observer

Packages that use Observer
Package
Description
java.util
Contains the collections framework, some internationalization support classes, a service loader, properties, random number generation, string parsing and scanning classes, base64 encoding and decoding, a bit array, and several miscellaneous utility classes.

## Uses of Observer in java.util

Methods in java.util with parameters of type Observer
Modifier and Type
Method
Description
`void`
Observable.`addObserver(Observer o)`
Deprecated.
Adds an observer to the set of observers for this object, provided that it is not the same as some observer already in the set.
`void`
Observable.`deleteObserver(Observer o)`
Deprecated.
Deletes an observer from the set of observers of this object.