# RecyclerView.Adapter 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.Adapter) Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) *** ** * ** *** ``` public abstract class RecyclerView.Adapter ```
Known direct subclasses [ConcatAdapter](https://developer.android.com/reference/androidx/recyclerview/widget/ConcatAdapter), [FragmentStateAdapter](https://developer.android.com/reference/androidx/viewpager2/adapter/FragmentStateAdapter), [ItemBridgeAdapter](https://developer.android.com/reference/androidx/leanback/widget/ItemBridgeAdapter), [LeanbackListPreferenceDialogFragment.AdapterMulti](https://developer.android.com/reference/androidx/leanback/preference/LeanbackListPreferenceDialogFragment.AdapterMulti), [LeanbackListPreferenceDialogFragment.AdapterSingle](https://developer.android.com/reference/androidx/leanback/preference/LeanbackListPreferenceDialogFragment.AdapterSingle), [ListAdapter](https://developer.android.com/reference/androidx/recyclerview/widget/ListAdapter), [LoadStateAdapter](https://developer.android.com/reference/androidx/paging/LoadStateAdapter), [PagedListAdapter](https://developer.android.com/reference/androidx/paging/PagedListAdapter), [PagingDataAdapter](https://developer.android.com/reference/androidx/paging/PagingDataAdapter) |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/ConcatAdapter` | An `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` implementation that presents the contents of multiple adapters in sequence. | | `https://developer.android.com/reference/androidx/viewpager2/adapter/FragmentStateAdapter` | Similar in behavior to `https://developer.android.com/reference/androidx/fragment/app/FragmentStatePagerAdapter` | | `https://developer.android.com/reference/androidx/leanback/widget/ItemBridgeAdapter` | Bridge from `https://developer.android.com/reference/androidx/leanback/widget/Presenter` to `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter`. | | `https://developer.android.com/reference/androidx/leanback/preference/LeanbackListPreferenceDialogFragment.AdapterMulti` | **This class is deprecated.** Ue LeanbackListPreferenceDialogFragmentCompat.
| | `https://developer.android.com/reference/androidx/leanback/preference/LeanbackListPreferenceDialogFragment.AdapterSingle` | **This class is deprecated.** Use LeanbackListPreferenceDialogFragmentCompat.
| | `https://developer.android.com/reference/androidx/recyclerview/widget/ListAdapter` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` base class for presenting List data in a `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView`, including computing diffs between Lists on a background thread. | | `https://developer.android.com/reference/androidx/paging/LoadStateAdapter` | Adapter for displaying a RecyclerView item based on `https://developer.android.com/reference/androidx/paging/LoadState`, such as a loading spinner, or a retry error button. | | `https://developer.android.com/reference/androidx/paging/PagedListAdapter` | **This class is deprecated.** PagedListAdapter is deprecated and has been replaced by PagingDataAdapter | | `https://developer.android.com/reference/androidx/paging/PagingDataAdapter` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` base class for presenting paged data from `https://developer.android.com/reference/androidx/paging/PagingData`s in a `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView`. | *** ** * ** *** Base class for an Adapter Adapters provide a binding from an app-specific data set to views that are displayed within a `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView`. | Parameters | |---|---| | `` | A class that extends ViewHolder that will be used by the adapter. | ## Summary | ### Nested types | |---| | `public enum https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy` Defines how this Adapter wants to restore its state after a view reconstruction (e.g. configuration change). | | ### Public constructors | |---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#Adapter()()` | | ### Public methods | |---|---| | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#bindViewHolder(VH,int)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder, int position)` This method internally calls `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)` to update the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` contents with the item at the given position and also sets up some private fields to be used by RecyclerView. | | `final @https://developer.android.com/reference/androidx/annotation/NonNull VH` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#createViewHolder(android.view.ViewGroup,int)(@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/android/view/ViewGroup.html parent, int viewType)` This method calls `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onCreateViewHolder(android.view.ViewGroup,int)` to create a new `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` and initializes some private fields to be used by RecyclerView. | | `int` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#findRelativeAdapterPositionIn(androidx.recyclerview.widget.RecyclerView.Adapter,androidx.recyclerview.widget.RecyclerView.ViewHolder,int)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter adapter, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder viewHolder, int localPosition )` Returns the position of the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` in the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter`. | | `abstract int` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getItemCount()()` Returns the total number of items in the data set held by the adapter. | | `long` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getItemId(int)(int position)` Return the stable ID for the item at `position`. | | `int` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getItemViewType(int)(int position)` Return the view type of the item at `position` for the purposes of view recycling. | | `final @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getStateRestorationPolicy()()` Returns when this Adapter wants to restore the state. | | `final boolean` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#hasObservers()()` Returns true if one or more observers are attached to this adapter. | | `final boolean` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#hasStableIds()()` Returns true if this adapter publishes a unique `long` value that can act as a key for the item at a given position in the data set. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyDataSetChanged()()` Notify any registered observers that the data set has changed. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int)(int position)` Notify any registered observers that the item at `position` has changed. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int,java.lang.Object)(int position, @https://developer.android.com/reference/androidx/annotation/Nullable https://developer.android.com/reference/java/lang/Object.html payload)` Notify any registered observers that the item at `position` has changed with an optional payload object. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemInserted(int)(int position)` Notify any registered observers that the item reflected at `position` has been newly inserted. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemMoved(int,int)(int fromPosition, int toPosition)` Notify any registered observers that the item reflected at `fromPosition` has been moved to `toPosition`. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int)(int positionStart, int itemCount)` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int,java.lang.Object)( int positionStart, int itemCount, @https://developer.android.com/reference/androidx/annotation/Nullable https://developer.android.com/reference/java/lang/Object.html payload )` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeInserted(int,int)(int positionStart, int itemCount)` Notify any registered observers that the currently reflected `itemCount` items starting at `positionStart` have been newly inserted. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeRemoved(int,int)(int positionStart, int itemCount)` Notify any registered observers that the `itemCount` items previously located at `positionStart` have been removed from the data set. | | `final void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRemoved(int)(int position)` Notify any registered observers that the item previously located at `position` has been removed from the data set. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onAttachedToRecyclerView(androidx.recyclerview.widget.RecyclerView)(@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView recyclerView)` Called by RecyclerView when it starts observing this Adapter. | | `abstract void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder, int position)` Called by RecyclerView to display the data at the specified position. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)( @https://developer.android.com/reference/androidx/annotation/NonNull VH holder, int position, @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html payloads )` Called by RecyclerView to display the data at the specified position. | | `abstract @https://developer.android.com/reference/androidx/annotation/NonNull VH` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onCreateViewHolder(android.view.ViewGroup,int)(@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/android/view/ViewGroup.html parent, int viewType)` Called when RecyclerView needs a new `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` of the given type to represent an item. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onDetachedFromRecyclerView(androidx.recyclerview.widget.RecyclerView)(@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView recyclerView)` Called by RecyclerView when it stops observing this Adapter. | | `boolean` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onFailedToRecycleView(VH)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder)` Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled due to its transient state. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onViewAttachedToWindow(VH)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder)` Called when a view created by this adapter has been attached to a window. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onViewDetachedFromWindow(VH)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder)` Called when a view created by this adapter has been detached from its window. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onViewRecycled(VH)(@https://developer.android.com/reference/androidx/annotation/NonNull VH holder)` Called when a view created by this adapter has been recycled. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#registerAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver observer )` Register a new observer to listen for data changes. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#setHasStableIds(boolean)(boolean hasStableIds)` Indicates whether each item in the data set can be represented with a unique identifier of type `https://developer.android.com/reference/java/lang/Long.html`. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#setStateRestorationPolicy(androidx.recyclerview.widget.RecyclerView.Adapter.StateRestorationPolicy)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy strategy )` Sets the state restoration strategy for the Adapter. | | `void` | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#unregisterAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)( @https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver observer )` Unregister an observer currently listening for data changes. | ## Public constructors ### Adapter Added in 1.0.0 ``` public Adapter() ``` ## Public methods ### bindViewHolder Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void bindViewHolder(@NonNull VH holder, int position) ``` This method internally calls `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)` to update the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` contents with the item at the given position and also sets up some private fields to be used by RecyclerView. Adapters that merge other adapters should use `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#bindViewHolder(VH,int)` when calling nested adapters so that RecyclerView can track which adapter bound the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` to return the correct position from `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#getBindingAdapterPosition()` method. They should also override the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#findRelativeAdapterPositionIn(androidx.recyclerview.widget.RecyclerView.Adapter,androidx.recyclerview.widget.RecyclerView.ViewHolder,int)` method. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | The view holder whose contents should be updated | | `int position` | The position of the holder with respect to this adapter | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)` | | ### createViewHolder Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final @NonNull VH createViewHolder(@NonNull ViewGroup parent, int viewType) ``` This method calls `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onCreateViewHolder(android.view.ViewGroup,int)` to create a new `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` and initializes some private fields to be used by RecyclerView. | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onCreateViewHolder(android.view.ViewGroup,int)` | | ### findRelativeAdapterPositionIn Added in [1.2.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.2.0) ``` public int findRelativeAdapterPositionIn(     @NonNull RecyclerView.Adapter adapter,     @NonNull RecyclerView.ViewHolder viewHolder,     int localPosition ) ``` Returns the position of the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` in the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter`. If the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` is not part of this `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter`, `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView#NO_POSITION()` is returned. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter adapter` | The adapter which is a sub adapter of this adapter or itself. | | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder viewHolder` | The ViewHolder whose local position in the given adapter will be returned. | | `int localPosition` | The position of the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` in this `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter`. | | Returns | |---|---| | `int` | The local position of the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` in this `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` or `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView#NO_POSITION()` if the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` is not bound to an item or the given `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter` is not part of this Adapter (if this Adapter merges other adapters). | ### getItemCount Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public abstract int getItemCount() ``` Returns the total number of items in the data set held by the adapter. | Returns | |---|---| | `int` | The total number of items in this adapter. | ### getItemId Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public long getItemId(int position) ``` Return the stable ID for the item at `position`. If `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#hasStableIds()` would return false this method should return `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView#NO_ID()`. The default implementation of this method returns `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView#NO_ID()`. | Parameters | |---|---| | `int position` | Adapter position to query | | Returns | |---|---| | `long` | the stable ID of the item at position | ### getItemViewType Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public int getItemViewType(int position) ``` Return the view type of the item at `position` for the purposes of view recycling. The default implementation of this method returns 0, making the assumption of a single view type for the adapter. Unlike ListView adapters, types need not be contiguous. Consider using id resources to uniquely identify item view types. | Parameters | |---|---| | `int position` | position to query | | Returns | |---|---| | `int` | integer value identifying the type of the view needed to represent the item at `position`. Type codes need not be contiguous. | ### getStateRestorationPolicy Added in [1.2.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.2.0) ``` public final @NonNull RecyclerView.Adapter.StateRestorationPolicy getStateRestorationPolicy() ``` Returns when this Adapter wants to restore the state. | Returns | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy` | The current `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy` for this Adapter. Defaults to `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#ALLOW`. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#setStateRestorationPolicy(androidx.recyclerview.widget.RecyclerView.Adapter.StateRestorationPolicy)` | | ### hasObservers Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final boolean hasObservers() ``` Returns true if one or more observers are attached to this adapter. | Returns | |---|---| | `boolean` | true if this adapter has observers | ### hasStableIds Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final boolean hasStableIds() ``` Returns true if this adapter publishes a unique `long` value that can act as a key for the item at a given position in the data set. If that item is relocated in the data set, the ID returned for that item should be the same. | Returns | |---|---| | `boolean` | true if this adapter's items have stable IDs | ### notifyDataSetChanged Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyDataSetChanged() ``` Notify any registered observers that the data set has changed. There are two different classes of data change events, item changes and structural changes. Item changes are when a single item has its data updated but no positional changes have occurred. Structural changes are when items are inserted, removed or moved within the data set. This event does not specify what about the data set has changed, forcing any observers to assume that all existing items and structure may no longer be valid. LayoutManagers will be forced to fully rebind and relayout all visible views. `RecyclerView` will attempt to synthesize visible structural change events for adapters that report that they have `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#hasStableIds()` when this method is used. This can help for the purposes of animation and visual object persistence but individual item views will still need to be rebound and relaid out. If you are writing an adapter it will always be more efficient to use the more specific change events if you can. Rely on `notifyDataSetChanged()` as a last resort. | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemInserted(int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRemoved(int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeInserted(int,int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeRemoved(int,int)` | | ### notifyItemChanged Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemChanged(int position) ``` Notify any registered observers that the item at `position` has changed. Equivalent to calling `notifyItemChanged(position, null);`. This is an item change event, not a structural change event. It indicates that any reflection of the data at `position` is out of date and should be updated. The item at `position` retains the same identity. | Parameters | |---|---| | `int position` | Position of the item that has changed | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int)` | | ### notifyItemChanged Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemChanged(int position, @Nullable Object payload) ``` Notify any registered observers that the item at `position` has changed with an optional payload object. This is an item change event, not a structural change event. It indicates that any reflection of the data at `position` is out of date and should be updated. The item at `position` retains the same identity. Client can optionally pass a payload for partial change. These payloads will be merged and may be passed to adapter's `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)` if the item is already represented by a ViewHolder and it will be rebound to the same ViewHolder. A notifyItemRangeChanged() with null payload will clear all existing payloads on that item and prevent future payload until `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)` is called. Adapter should not assume that the payload will always be passed to onBindViewHolder(), e.g. when the view is not attached, the payload will be simply dropped. | Parameters | |---|---| | `int position` | Position of the item that has changed | | `@https://developer.android.com/reference/androidx/annotation/Nullable https://developer.android.com/reference/java/lang/Object.html payload` | Optional parameter, use null to identify a "full" update | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int)` | | ### notifyItemInserted Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemInserted(int position) ``` Notify any registered observers that the item reflected at `position` has been newly inserted. The item previously at `position` is now at position `position + 1`. This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered. | Parameters | |---|---| | `int position` | Position of the newly inserted item in the data set | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeInserted(int,int)` | | ### notifyItemMoved Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemMoved(int fromPosition, int toPosition) ``` Notify any registered observers that the item reflected at `fromPosition` has been moved to `toPosition`. This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered. | Parameters | |---|---| | `int fromPosition` | Previous position of the item. | | `int toPosition` | New position of the item. | ### notifyItemRangeChanged Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemRangeChanged(int positionStart, int itemCount) ``` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed. Equivalent to calling `notifyItemRangeChanged(position, itemCount, null);`. This is an item change event, not a structural change event. It indicates that any reflection of the data in the given position range is out of date and should be updated. The items in the given range retain the same identity. | Parameters | |---|---| | `int positionStart` | Position of the first item that has changed | | `int itemCount` | Number of items that have changed | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int)` | | ### notifyItemRangeChanged Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemRangeChanged(     int positionStart,     int itemCount,     @Nullable Object payload ) ``` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed. An optional payload can be passed to each changed item. This is an item change event, not a structural change event. It indicates that any reflection of the data in the given position range is out of date and should be updated. The items in the given range retain the same identity. Client can optionally pass a payload for partial change. These payloads will be merged and may be passed to adapter's `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)` if the item is already represented by a ViewHolder and it will be rebound to the same ViewHolder. A notifyItemRangeChanged() with null payload will clear all existing payloads on that item and prevent future payload until `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)` is called. Adapter should not assume that the payload will always be passed to onBindViewHolder(), e.g. when the view is not attached, the payload will be simply dropped. | Parameters | |---|---| | `int positionStart` | Position of the first item that has changed | | `int itemCount` | Number of items that have changed | | `@https://developer.android.com/reference/androidx/annotation/Nullable https://developer.android.com/reference/java/lang/Object.html payload` | Optional parameter, use null to identify a "full" update | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int)` | | ### notifyItemRangeInserted Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemRangeInserted(int positionStart, int itemCount) ``` Notify any registered observers that the currently reflected `itemCount` items starting at `positionStart` have been newly inserted. The items previously located at `positionStart` and beyond can now be found starting at position `positionStart + itemCount`. This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered. | Parameters | |---|---| | `int positionStart` | Position of the first item that was inserted | | `int itemCount` | Number of items inserted | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemInserted(int)` | | ### notifyItemRangeRemoved Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemRangeRemoved(int positionStart, int itemCount) ``` Notify any registered observers that the `itemCount` items previously located at `positionStart` have been removed from the data set. The items previously located at and after `positionStart + itemCount` may now be found at `oldPosition - itemCount`. This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered. | Parameters | |---|---| | `int positionStart` | Previous position of the first item that was removed | | `int itemCount` | Number of items removed from the data set | ### notifyItemRemoved Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public final void notifyItemRemoved(int position) ``` Notify any registered observers that the item previously located at `position` has been removed from the data set. The items previously located at and after `position` may now be found at `oldPosition - 1`. This is a structural change event. Representations of other existing items in the data set are still considered up to date and will not be rebound, though their positions may be altered. | Parameters | |---|---| | `int position` | Position of the item that has now been removed | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeRemoved(int,int)` | | ### onAttachedToRecyclerView Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) ``` Called by RecyclerView when it starts observing this Adapter. Keep in mind that same adapter may be observed by multiple RecyclerViews. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView recyclerView` | The RecyclerView instance which started observing this adapter. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onDetachedFromRecyclerView(androidx.recyclerview.widget.RecyclerView)` | | ### onBindViewHolder Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public abstract void onBindViewHolder(@NonNull VH holder, int position) ``` Called by RecyclerView to display the data at the specified position. This method should update the contents of the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#itemView()` to reflect the item at the given position. Note that unlike `https://developer.android.com/reference/android/widget/ListView.html`, RecyclerView will not call this method again if the position of the item changes in the data set unless the item itself is invalidated or the new position cannot be determined. For this reason, you should only use the `position` parameter while acquiring the related data item inside this method and should not keep a copy of it. If you need the position of an item later on (e.g. in a click listener), use `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#getBindingAdapterPosition()` which will have the updated adapter position. Override `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)` instead if Adapter can handle efficient partial bind. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | The ViewHolder which should be updated to represent the contents of the item at the given position in the data set. | | `int position` | The position of the item within the adapter's data set. | ### onBindViewHolder Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onBindViewHolder(     @NonNull VH holder,     int position,     @NonNull List payloads ) ``` Called by RecyclerView to display the data at the specified position. This method should update the contents of the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#itemView()` to reflect the item at the given position. Note that unlike `https://developer.android.com/reference/android/widget/ListView.html`, RecyclerView will not call this method again if the position of the item changes in the data set unless the item itself is invalidated or the new position cannot be determined. For this reason, you should only use the `position` parameter while acquiring the related data item inside this method and should not keep a copy of it. If you need the position of an item later on (e.g. in a click listener), use `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#getBindingAdapterPosition()` which will have the updated adapter position. Partial bind vs full bind: The payloads parameter is a merge list from `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemChanged(int,java.lang.Object)` or `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#notifyItemRangeChanged(int,int,java.lang.Object)`. If the payloads list is not empty, the ViewHolder is currently bound to old data and Adapter may run an efficient partial update using the payload info. If the payload is empty, Adapter must run a full bind. Adapter should not assume that the payload passed in notify methods will be received by onBindViewHolder(). For example when the view is not attached to the screen, the payload in notifyItemChange() will be simply dropped. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | The ViewHolder which should be updated to represent the contents of the item at the given position in the data set. | | `int position` | The position of the item within the adapter's data set. | | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/java/util/List.html payloads` | A non-null list of merged payloads. Can be empty list if requires full update. | ### onCreateViewHolder Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public abstract @NonNull VH onCreateViewHolder(@NonNull ViewGroup parent, int viewType) ``` Called when RecyclerView needs a new `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder` of the given type to represent an item. This new ViewHolder should be constructed with a new View that can represent the items of the given type. You can either create a new View manually or inflate it from an XML layout file. The new ViewHolder will be used to display items of the adapter using `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int,java.util.List)`. Since it will be re-used to display different items in the data set, it is a good idea to cache references to sub views of the View to avoid unnecessary `https://developer.android.com/reference/android/view/View.html#findViewById(int)` calls. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/android/view/ViewGroup.html parent` | The ViewGroup into which the new View will be added after it is bound to an adapter position. | | `int viewType` | The view type of the new View. | | Returns | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH` | A new ViewHolder that holds a View of the given view type. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getItemViewType(int)` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)` | | ### onDetachedFromRecyclerView Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onDetachedFromRecyclerView(@NonNull RecyclerView recyclerView) ``` Called by RecyclerView when it stops observing this Adapter. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView recyclerView` | The RecyclerView instance which stopped observing this adapter. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onAttachedToRecyclerView(androidx.recyclerview.widget.RecyclerView)` | | ### onFailedToRecycleView Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public boolean onFailedToRecycleView(@NonNull VH holder) ``` Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled due to its transient state. Upon receiving this callback, Adapter can clear the animation(s) that effect the View's transient state and return `true` so that the View can be recycled. Keep in mind that the View in question is already removed from the RecyclerView. In some cases, it is acceptable to recycle a View although it has transient state. Most of the time, this is a case where the transient state will be cleared in `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onBindViewHolder(VH,int)` call when View is rebound to a new position. For this reason, RecyclerView leaves the decision to the Adapter and uses the return value of this method to decide whether the View should be recycled or not. Note that when all animations are created by `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ItemAnimator`, you should never receive this callback because RecyclerView keeps those Views as children until their animations are complete. This callback is useful when children of the item views create animations which may not be easy to implement using an `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ItemAnimator`. You should *never* fix this issue by calling `holder.itemView.setHasTransientState(false);` unless you've previously called `holder.itemView.setHasTransientState(true);`. Each `View.setHasTransientState(true)` call must be matched by a `View.setHasTransientState(false)` call, otherwise, the state of the View may become inconsistent. You should always prefer to end or cancel animations that are triggering the transient state instead of handling it manually. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | The ViewHolder containing the View that could not be recycled due to its transient state. | | Returns | |---|---| | `boolean` | True if the View should be recycled, false otherwise. Note that if this method returns `true`, RecyclerView *will ignore* the transient state of the View and recycle it regardless. If this method returns `false`, RecyclerView will check the View's transient state again before giving a final decision. Default implementation returns false. | ### onViewAttachedToWindow Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onViewAttachedToWindow(@NonNull VH holder) ``` Called when a view created by this adapter has been attached to a window. This can be used as a reasonable signal that the view is about to be seen by the user. If the adapter previously freed any resources in `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#onViewDetachedFromWindow(VH)` those resources should be restored here. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | Holder of the view being attached | ### onViewDetachedFromWindow Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onViewDetachedFromWindow(@NonNull VH holder) ``` Called when a view created by this adapter has been detached from its window. Becoming detached from the window is not necessarily a permanent condition; the consumer of an Adapter's views may choose to cache views offscreen while they are not visible, attaching and detaching them as appropriate. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | Holder of the view being detached | ### onViewRecycled Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void onViewRecycled(@NonNull VH holder) ``` Called when a view created by this adapter has been recycled. A view is recycled when a `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.LayoutManager` decides that it no longer needs to be attached to its parent `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView`. This can be because it has fallen out of visibility or a set of cached views represented by views still attached to the parent RecyclerView. If an item view has large or expensive data bound to it such as large bitmaps, this may be a good place to release those resources. RecyclerView calls this method right before clearing ViewHolder's internal data and sending it to RecycledViewPool. This way, if ViewHolder was holding valid information before being recycled, you can call `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.ViewHolder#getBindingAdapterPosition()` to get its adapter position. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull VH holder` | The ViewHolder for the view being recycled | ### registerAdapterDataObserver Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void registerAdapterDataObserver(     @NonNull RecyclerView.AdapterDataObserver observer ) ``` Register a new observer to listen for data changes. The adapter may publish a variety of events describing specific changes. Not all adapters may support all change types and some may fall back to a generic `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver#onChanged()` event if more specific data is not available. Components registering observers with an adapter are responsible for `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#unregisterAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)` those observers when finished. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver observer` | Observer to register | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#unregisterAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)` | | ### setHasStableIds Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void setHasStableIds(boolean hasStableIds) ``` Indicates whether each item in the data set can be represented with a unique identifier of type `https://developer.android.com/reference/java/lang/Long.html`. | Parameters | |---|---| | `boolean hasStableIds` | Whether items in data set have unique identifiers or not. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#hasStableIds()` | | | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getItemId(int)` | | ### setStateRestorationPolicy Added in [1.2.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.2.0) ``` public void setStateRestorationPolicy(     @NonNull RecyclerView.Adapter.StateRestorationPolicy strategy ) ``` Sets the state restoration strategy for the Adapter. By default, it is set to `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#ALLOW` which means RecyclerView expects any set Adapter to be immediately capable of restoring the RecyclerView's saved scroll position. This behaviour might be undesired if the Adapter's data is loaded asynchronously, and thus unavailable during initial layout (e.g. after Activity rotation). To avoid losing scroll position, you can change this to be either `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#PREVENT_WHEN_EMPTY` or `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#PREVENT`. Note that the former means your RecyclerView will restore state as soon as Adapter has 1 or more items while the latter requires you to call `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#setStateRestorationPolicy(androidx.recyclerview.widget.RecyclerView.Adapter.StateRestorationPolicy)` with either `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#ALLOW` or `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy#PREVENT_WHEN_EMPTY` again when the Adapter is ready to restore its state. RecyclerView will still layout even when State restoration is disabled. The behavior of how State is restored is up to the `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.LayoutManager`. All default LayoutManagers will override current state with restored state when state restoration happens (unless an explicit call to `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.LayoutManager#scrollToPosition(int)` is made). Calling this method after state is restored will not have any effect other than changing the return value of `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getStateRestorationPolicy()`. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter.StateRestorationPolicy strategy` | The saved state restoration strategy for this Adapter. | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#getStateRestorationPolicy()` | | ### unregisterAdapterDataObserver Added in [1.0.0](https://developer.android.com/jetpack/androidx/releases/recyclerview#1.0.0) ``` public void unregisterAdapterDataObserver(     @NonNull RecyclerView.AdapterDataObserver observer ) ``` Unregister an observer currently listening for data changes. The unregistered observer will no longer receive events about changes to the adapter. | Parameters | |---|---| | `@https://developer.android.com/reference/androidx/annotation/NonNull https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.AdapterDataObserver observer` | Observer to unregister | | See also | |---|---| | `https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.Adapter#registerAdapterDataObserver(androidx.recyclerview.widget.RecyclerView.AdapterDataObserver)` | |