# Observer

Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)  
Deprecated in[API level 33](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)  

# Observer

`
public


interface
Observer
`  
`


`

|--------------------|
| java.util.Observer |

<br />

*** ** * ** ***

<br />

**This interface was deprecated in API level 33.**   
This interface has been deprecated. See the[Observable](https://developer.android.com/reference/java/util/Observable)class for further information.

A class can implement the`Observer`interface when it wants to be informed of changes in observable objects.  
**See also:**

- [Observable](https://developer.android.com/reference/java/util/Observable)

## Summary

|                                                                                                                                                                           ### Public methods                                                                                                                                                                           ||
|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ` abstract void` | ` `[update](https://developer.android.com/reference/java/util/Observer#update(java.util.Observable,%20java.lang.Object))`(`[Observable](https://developer.android.com/reference/java/util/Observable)` o, `[Object](https://developer.android.com/reference/java/lang/Object)` arg) ` This method is called whenever the observed object is changed. |

## Public methods

### update

Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)  

```
public abstract void update (Observable o, 
                Object arg)
```

This method is called whenever the observed object is changed. An application calls an`Observable`object's`notifyObservers`method to have all the object's observers notified of the change.

<br />

|                                Parameters                                 ||
|-------|--------------------------------------------------------------------|
| `o`   | `Observable`: the observable object. <br />                        |
| `arg` | `Object`: an argument passed to the`notifyObservers`method. <br /> |