# DataSetObserver

Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)  
Summary:[Ctors](https://developer.android.com/reference/android/database/DataSetObserver#pubctors)\|[Methods](https://developer.android.com/reference/android/database/DataSetObserver#pubmethods)\|[Inherited Methods](https://developer.android.com/reference/android/database/DataSetObserver#inhmethods)  

# DataSetObserver

*** ** * ** ***

[Kotlin](https://developer.android.com/reference/kotlin/android/database/DataSetObserver "View this page in Kotlin")\|Java

`
public


abstract
class
DataSetObserver
`  
`

extends `[Object](https://developer.android.com/reference/java/lang/Object)`


``


`

|---|----------------------------------|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.database.DataSetObserver |

|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Known direct subclasses [AlphabetIndexer](https://developer.android.com/reference/android/widget/AlphabetIndexer) |-------------------------------------------------------------------------------------------|--------------------------------------------------------------------------| | [AlphabetIndexer](https://developer.android.com/reference/android/widget/AlphabetIndexer) | A helper class for adapters that implement the SectionIndexer interface. | |

<br />

*** ** * ** ***

Receives call backs when a data set has been changed, or made invalid. The typically data sets that are observed are[Cursor](https://developer.android.com/reference/android/database/Cursor)s or[Adapter](https://developer.android.com/reference/android/widget/Adapter)s. DataSetObserver must be implemented by objects which are added to a DataSetObservable.

## Summary

|                                                 ### Public constructors                                                  ||
|-----------------------------------------------------------------------------------------------------------------------|---|
| ` `[DataSetObserver](https://developer.android.com/reference/android/database/DataSetObserver#DataSetObserver())`() ` |

|                                                                                                                                                                                                                                        ### Public methods                                                                                                                                                                                                                                        ||
|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ` void` | ` `[onChanged](https://developer.android.com/reference/android/database/DataSetObserver#onChanged())`() ` This method is called when the entire data set has changed, most likely through a call to[Cursor.requery()](https://developer.android.com/reference/android/database/Cursor#requery())on a[Cursor](https://developer.android.com/reference/android/database/Cursor).                                                                                                          |
| ` void` | ` `[onInvalidated](https://developer.android.com/reference/android/database/DataSetObserver#onInvalidated())`() ` This method is called when the entire data becomes invalid, most likely through a call to[Cursor.deactivate()](https://developer.android.com/reference/android/database/Cursor#deactivate())or[Cursor.close()](https://developer.android.com/reference/android/database/Cursor#close())on a[Cursor](https://developer.android.com/reference/android/database/Cursor). |

| ### Inherited methods |
|-----------------------|---|
| From class` `[java.lang.Object](https://developer.android.com/reference/java/lang/Object)` ` |--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](https://developer.android.com/reference/java/lang/Object)          | ` `[clone](https://developer.android.com/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object.                                                                                                                                                      | | ` boolean`                                                                     | ` `[equals](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` obj) ` Indicates whether some other object is "equal to" this one.                                           | | ` void`                                                                        | ` `[finalize](https://developer.android.com/reference/java/lang/Object#finalize())`() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.                                                          | | ` final `[Class](https://developer.android.com/reference/java/lang/Class)`<?>` | ` `[getClass](https://developer.android.com/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this`Object`.                                                                                                                                                | | ` int`                                                                         | ` `[hashCode](https://developer.android.com/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object.                                                                                                                                                 | | ` final void`                                                                  | ` `[notify](https://developer.android.com/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor.                                                                                                                            | | ` final void`                                                                  | ` `[notifyAll](https://developer.android.com/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor.                                                                                                                         | | ` `[String](https://developer.android.com/reference/java/lang/String)          | ` `[toString](https://developer.android.com/reference/java/lang/Object#toString())`() ` Returns a string representation of the object.                                                                                                                                            | | ` final void`                                                                  | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long,%20int))`(long timeoutMillis, int nanos) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed. | | ` final void`                                                                  | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long))`(long timeoutMillis) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed.                   | | ` final void`                                                                  | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait())`() ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*.                                                                                             | ||

## Public constructors

### DataSetObserver

```
public DataSetObserver ()
```

<br />

<br />

## Public methods

### onChanged

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

```
public void onChanged ()
```

This method is called when the entire data set has changed, most likely through a call to[Cursor.requery()](https://developer.android.com/reference/android/database/Cursor#requery())on a[Cursor](https://developer.android.com/reference/android/database/Cursor).

<br />

### onInvalidated

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

```
public void onInvalidated ()
```

This method is called when the entire data becomes invalid, most likely through a call to[Cursor.deactivate()](https://developer.android.com/reference/android/database/Cursor#deactivate())or[Cursor.close()](https://developer.android.com/reference/android/database/Cursor#close())on a[Cursor](https://developer.android.com/reference/android/database/Cursor).

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