# RecyclerView.AdapterDataObserver

# RecyclerView.AdapterDataObserver

Artifact:[androidx.recyclerview:recyclerview](https://developer.android.com/jetpack/androidx/releases/recyclerview)  
[View Source](https://cs.android.com/search?q=file:androidx/recyclerview/widget/RecyclerView.java+class:androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)  
Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)

*** ** * ** ***

Kotlin\|[Java](https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver "View this page in Java")

<br />

```
abstract class RecyclerView.AdapterDataObserver
```

<br />

*** ** * ** ***

Observer base class for watching changes to an[Adapter](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter). See[registerAdapterDataObserver](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter#registerAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)).

## Summary

|                                                                    ### Public constructors                                                                    |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [AdapterDataObserver](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#AdapterDataObserver())`()` |

|                             ### Public functions                              |
|-------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onChanged](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onChanged())`()`                                                                                                                                                                                                                                                                                                                                               |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onItemRangeChanged](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onItemRangeChanged(int,int))`(positionStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, itemCount: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)`                                                                                                                                |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onItemRangeChanged](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onItemRangeChanged(int,int,java.lang.Object))`(positionStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, itemCount: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, payload: `[Any](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-any/index.html)`?)`                      |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onItemRangeInserted](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onItemRangeInserted(int,int))`(positionStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, itemCount: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)`                                                                                                                              |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onItemRangeMoved](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onItemRangeMoved(int,int,int))`(fromPosition: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, toPosition: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, itemCount: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)`                                      |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onItemRangeRemoved](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onItemRangeRemoved(int,int))`(positionStart: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`, itemCount: `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)`)`                                                                                                                                |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [onStateRestorationPolicyChanged](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onStateRestorationPolicyChanged())`()` Called when the[Adapter.StateRestorationPolicy](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy)of the[Adapter](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter)changed. |

## Public constructors

### AdapterDataObserver

Added in 1.0.0  

```
AdapterDataObserver()
```  

## Public functions

### onChanged

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onChanged(): Unit
```  

### onItemRangeChanged

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onItemRangeChanged(positionStart: Int, itemCount: Int): Unit
```  

### onItemRangeChanged

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onItemRangeChanged(positionStart: Int, itemCount: Int, payload: Any?): Unit
```  

### onItemRangeInserted

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onItemRangeInserted(positionStart: Int, itemCount: Int): Unit
```  

### onItemRangeMoved

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onItemRangeMoved(fromPosition: Int, toPosition: Int, itemCount: Int): Unit
```  

### onItemRangeRemoved

Added in[1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0)  

```
fun onItemRangeRemoved(positionStart: Int, itemCount: Int): Unit
```  

### onStateRestorationPolicyChanged

Added in[1.2.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.2.0)  

```
fun onStateRestorationPolicyChanged(): Unit
```

Called when the[Adapter.StateRestorationPolicy](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy)of the[Adapter](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter)changed. When this method is called, the Adapter might be ready to restore its state if it has not already been restored.  

|                                                                                                             See also                                                                                                              |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| [getStateRestorationPolicy](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter#getStateRestorationPolicy())                                                                         |   |
| [setStateRestorationPolicy](https://developer.android.com/reference/kotlin/androidx/recyclerview/widget/RecyclerView.Adapter#setStateRestorationPolicy(androidx.recyclerview.widget.RecyclerView.Adapter.StateRestorationPolicy)) |   |