Summary: Nested Classes | Ctors | Methods | Inherited Methods

ConcatAdapter

Kotlin |Java

public final class ConcatAdapter
extends Adapter<RecyclerView.ViewHolder>

java.lang.Object
↳	androidx.recyclerview.widget.RecyclerView.Adapter<androidx.recyclerview.widget.RecyclerView.ViewHolder>
	↳	androidx.recyclerview.widget.ConcatAdapter

An RecyclerView.Adapter implementation that presents the contents of multiple adapters in sequence.

 MyAdapter adapter1 = ...;
 AnotherAdapter adapter2 = ...;
 ConcatAdapter concatenated = new ConcatAdapter(adapter1, adapter2);
 recyclerView.setAdapter(concatenated);

By default, ConcatAdapter isolates view types of nested adapters from each other such that it will change the view type before reporting it back to the RecyclerView to avoid any conflicts between the view types of added adapters. This also means each added adapter will have its own isolated pool of RecyclerView.ViewHolders, with no re-use in between added adapters.

If your RecyclerView.Adapters share the same view types, and can support sharing RecyclerView.ViewHolder s between added adapters, provide an instance of ConcatAdapter.Config where you set ConcatAdapter.Config.isolateViewTypes to false. A common usage pattern for this is to return the R.layout.<layout_name> from the RecyclerView.Adapter.getItemViewType(int) method.

When an added adapter calls one of the notify methods, ConcatAdapter properly offsets values before reporting it back to the RecyclerView. If an adapter calls RecyclerView.Adapter.notifyDataSetChanged(), ConcatAdapter also calls RecyclerView.Adapter.notifyDataSetChanged() as calling RecyclerView.Adapter.notifyItemRangeChanged(int, int) will confuse the RecyclerView. You are highly encouraged to to use SortedList or ListAdapter to avoid calling RecyclerView.Adapter.notifyDataSetChanged().

Whether ConcatAdapter should support stable ids is defined in the ConcatAdapter.Config object. Calling RecyclerView.Adapter.setHasStableIds(boolean) has no effect. See documentation for ConcatAdapter.Config.StableIdMode for details on how to configure ConcatAdapter to use stable ids. By default, it will not use stable ids and sub adapter stable ids will be ignored. Similar to the case above, you are highly encouraged to use ListAdapter, which will automatically calculate the changes in the data set for you so you won't need stable ids.

It is common to find the adapter position of a RecyclerView.ViewHolder to handle user action on the RecyclerView.ViewHolder. For those cases, instead of calling RecyclerView.ViewHolder.getAdapterPosition(), use RecyclerView.ViewHolder.getBindingAdapterPosition(). If your adapters share RecyclerView.ViewHolders, you can use the RecyclerView.ViewHolder.getBindingAdapter() method to find the adapter which last bound that RecyclerView.ViewHolder.

Summary

Nested classes
`class`	`ConcatAdapter.Config` The configuration object for a `ConcatAdapter`.

Public constructors
`ConcatAdapter(Adapter...<? extends RecyclerView.ViewHolder> adapters)` Creates a ConcatAdapter with `ConcatAdapter.Config.DEFAULT` and the given adapters in the given order.
`ConcatAdapter(ConcatAdapter.Config config, Adapter...<? extends RecyclerView.ViewHolder> adapters)` Creates a ConcatAdapter with the given config and the given adapters in the given order.
`ConcatAdapter(List<? extends Adapter<? extends RecyclerView.ViewHolder>> adapters)` Creates a ConcatAdapter with `ConcatAdapter.Config.DEFAULT` and the given adapters in the given order.
`ConcatAdapter(ConcatAdapter.Config config, List<? extends Adapter<? extends RecyclerView.ViewHolder>> adapters)` Creates a ConcatAdapter with the given config and the given adapters in the given order.

Public methods
`boolean`	`addAdapter(Adapter<? extends RecyclerView.ViewHolder> adapter)` Appends the given adapter to the existing list of adapters and notifies the observers of this `ConcatAdapter`.
`boolean`	`addAdapter(int index, Adapter<? extends RecyclerView.ViewHolder> adapter)` Adds the given adapter to the given index among other adapters that are already added.
`int`	`findRelativeAdapterPositionIn(Adapter<? extends RecyclerView.ViewHolder> adapter, RecyclerView.ViewHolder viewHolder, int localPosition)` Returns the position of the given `RecyclerView.ViewHolder` in the given `RecyclerView.Adapter`.
`List<? extends Adapter<? extends RecyclerView.ViewHolder>>`	`getAdapters()` Returns an unmodifiable copy of the list of adapters in this `ConcatAdapter`.
`int`	`getItemCount()` Returns the total number of items in the data set held by the adapter.
`long`	`getItemId(int position)` Return the stable ID for the item at `position`.
`int`	`getItemViewType(int position)` Return the view type of the item at `position` for the purposes of view recycling.
`void`	`onAttachedToRecyclerView(RecyclerView recyclerView)` Called by RecyclerView when it starts observing this Adapter.
`void`	`onBindViewHolder(RecyclerView.ViewHolder holder, int position)` Called by RecyclerView to display the data at the specified position.
`RecyclerView.ViewHolder`	`onCreateViewHolder(ViewGroup parent, int viewType)` Called when RecyclerView needs a new `RecyclerView.ViewHolder` of the given type to represent an item.
`void`	`onDetachedFromRecyclerView(RecyclerView recyclerView)` Called by RecyclerView when it stops observing this Adapter.
`boolean`	`onFailedToRecycleView(RecyclerView.ViewHolder holder)` Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled due to its transient state.
`void`	`onViewAttachedToWindow(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been attached to a window.
`void`	`onViewDetachedFromWindow(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been detached from its window.
`void`	`onViewRecycled(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been recycled.
`boolean`	`removeAdapter(Adapter<? extends RecyclerView.ViewHolder> adapter)` Removes the given adapter from the adapters list if it exists
`void`	`setHasStableIds(boolean hasStableIds)` Calling this method is an error and will result in an `UnsupportedOperationException`.
`void`	`setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy strategy)` Calling this method is an error and will result in an `UnsupportedOperationException`.

Inherited methods

From class


        
          androidx.recyclerview.widget.RecyclerView.Adapter

`final void`	`bindViewHolder(RecyclerView.ViewHolder holder, int position)` This method internally calls `onBindViewHolder(ViewHolder, int)` to update the `RecyclerView.ViewHolder` contents with the item at the given position and also sets up some private fields to be used by RecyclerView.
`final RecyclerView.ViewHolder`	`createViewHolder(ViewGroup parent, int viewType)` This method calls `onCreateViewHolder(ViewGroup, int)` to create a new `RecyclerView.ViewHolder` and initializes some private fields to be used by RecyclerView.
`int`	`findRelativeAdapterPositionIn(Adapter<? extends RecyclerView.ViewHolder> adapter, RecyclerView.ViewHolder viewHolder, int localPosition)` Returns the position of the given `RecyclerView.ViewHolder` in the given `RecyclerView.Adapter`.
`abstract int`	`getItemCount()` Returns the total number of items in the data set held by the adapter.
`long`	`getItemId(int position)` Return the stable ID for the item at `position`.
`int`	`getItemViewType(int position)` Return the view type of the item at `position` for the purposes of view recycling.
`final RecyclerView.Adapter.StateRestorationPolicy`	`getStateRestorationPolicy()` Returns when this Adapter wants to restore the state.
`final boolean`	`hasObservers()` Returns true if one or more observers are attached to this adapter.
`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.
`final void`	`notifyDataSetChanged()` Notify any registered observers that the data set has changed.
`final void`	`notifyItemChanged(int position, Object payload)` Notify any registered observers that the item at `position` has changed with an optional payload object.
`final void`	`notifyItemChanged(int position)` Notify any registered observers that the item at `position` has changed.
`final void`	`notifyItemInserted(int position)` Notify any registered observers that the item reflected at `position` has been newly inserted.
`final void`	`notifyItemMoved(int fromPosition, int toPosition)` Notify any registered observers that the item reflected at `fromPosition` has been moved to `toPosition`.
`final void`	`notifyItemRangeChanged(int positionStart, int itemCount, Object payload)` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed.
`final void`	`notifyItemRangeChanged(int positionStart, int itemCount)` Notify any registered observers that the `itemCount` items starting at position `positionStart` have changed.
`final void`	`notifyItemRangeInserted(int positionStart, int itemCount)` Notify any registered observers that the currently reflected `itemCount` items starting at `positionStart` have been newly inserted.
`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.
`final void`	`notifyItemRemoved(int position)` Notify any registered observers that the item previously located at `position` has been removed from the data set.
`void`	`onAttachedToRecyclerView(RecyclerView recyclerView)` Called by RecyclerView when it starts observing this Adapter.
`abstract void`	`onBindViewHolder(RecyclerView.ViewHolder holder, int position)` Called by RecyclerView to display the data at the specified position.
`void`	`onBindViewHolder(RecyclerView.ViewHolder holder, int position, List<Object> payloads)` Called by RecyclerView to display the data at the specified position.
`abstract RecyclerView.ViewHolder`	`onCreateViewHolder(ViewGroup parent, int viewType)` Called when RecyclerView needs a new `RecyclerView.ViewHolder` of the given type to represent an item.
`void`	`onDetachedFromRecyclerView(RecyclerView recyclerView)` Called by RecyclerView when it stops observing this Adapter.
`boolean`	`onFailedToRecycleView(RecyclerView.ViewHolder holder)` Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled due to its transient state.
`void`	`onViewAttachedToWindow(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been attached to a window.
`void`	`onViewDetachedFromWindow(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been detached from its window.
`void`	`onViewRecycled(RecyclerView.ViewHolder holder)` Called when a view created by this adapter has been recycled.
`void`	`registerAdapterDataObserver(RecyclerView.AdapterDataObserver observer)` Register a new observer to listen for data changes.
`void`	`setHasStableIds(boolean hasStableIds)` Indicates whether each item in the data set can be represented with a unique identifier of type `Long`.
`void`	`setStateRestorationPolicy(RecyclerView.Adapter.StateRestorationPolicy strategy)` Sets the state restoration strategy for the Adapter.
`void`	`unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver observer)` Unregister an observer currently listening for data changes.

From class


        
          java.lang.Object

`Object`	`clone()`
`boolean`	`equals(Object arg0)`
`void`	`finalize()`
`final Class<?>`	`getClass()`
`int`	`hashCode()`
`final void`	`notify()`
`final void`	`notifyAll()`
`String`	`toString()`
`final void`	`wait(long arg0, int arg1)`
`final void`	`wait(long arg0)`
`final void`	`wait()`

Public constructors

public ConcatAdapter (Adapter...<? extends RecyclerView.ViewHolder> adapters)

Creates a ConcatAdapter with ConcatAdapter.Config.DEFAULT and the given adapters in the given order.

Parameters
`adapters`	`Adapter`: The list of adapters to add

public ConcatAdapter (ConcatAdapter.Config config, 
                Adapter...<? extends RecyclerView.ViewHolder> adapters)

Creates a ConcatAdapter with the given config and the given adapters in the given order.

Parameters
`config`	`ConcatAdapter.Config`: The configuration for this ConcatAdapter
`adapters`	`Adapter`: The list of adapters to add

See also:

ConcatAdapter.Config.Builder

public ConcatAdapter (List<? extends Adapter<? extends RecyclerView.ViewHolder>> adapters)

Creates a ConcatAdapter with ConcatAdapter.Config.DEFAULT and the given adapters in the given order.

Parameters
`adapters`	`List`: The list of adapters to add

public ConcatAdapter (ConcatAdapter.Config config, 
                List<? extends Adapter<? extends RecyclerView.ViewHolder>> adapters)

Creates a ConcatAdapter with the given config and the given adapters in the given order.

Parameters
`config`	`ConcatAdapter.Config`: The configuration for this ConcatAdapter
`adapters`	`List`: The list of adapters to add

See also:

ConcatAdapter.Config.Builder

Public methods

public boolean addAdapter (Adapter<? extends RecyclerView.ViewHolder> adapter)

Appends the given adapter to the existing list of adapters and notifies the observers of this ConcatAdapter.

Parameters
`adapter`	`Adapter`: The new adapter to add

Returns
`boolean`	`true` if the adapter is successfully added because it did not already exist, `false` otherwise.

See also:

public boolean addAdapter (int index, 
                Adapter<? extends RecyclerView.ViewHolder> adapter)

Adds the given adapter to the given index among other adapters that are already added.

Parameters
`index`	`int`: The index into which to insert the adapter. ConcatAdapter will throw an `IndexOutOfBoundsException` if the index is not between 0 and current adapter count (inclusive).
`adapter`	`Adapter`: The new adapter to add to the adapters list.

Returns
`boolean`	`true` if the adapter is successfully added because it did not already exist, `false` otherwise.

See also:

public int findRelativeAdapterPositionIn (Adapter<? extends RecyclerView.ViewHolder> adapter, 
                RecyclerView.ViewHolder viewHolder, 
                int localPosition)

Returns the position of the given RecyclerView.ViewHolder in the given RecyclerView.Adapter. If the given RecyclerView.Adapter is not part of this ConcatAdapter, RecyclerView.NO_POSITION is returned.

Parameters
`adapter`	`Adapter`: The adapter which is a sub adapter of this ConcatAdapter or itself.
`viewHolder`	`RecyclerView.ViewHolder`: The view holder whose local position in the given adapter will be returned.
`localPosition`	`int`: The position of the given `RecyclerView.ViewHolder` in this `RecyclerView.Adapter`.

Returns
`int`	The local position of the given `RecyclerView.ViewHolder` in the given `RecyclerView.Adapter` or `RecyclerView.NO_POSITION` if the `RecyclerView.ViewHolder` is not bound to an item or the given `RecyclerView.Adapter` is not part of this ConcatAdapter.

getAdapters

public List<? extends Adapter<? extends RecyclerView.ViewHolder>> getAdapters ()

Returns an unmodifiable copy of the list of adapters in this ConcatAdapter. Note that this is a copy hence future changes in the ConcatAdapter are not reflected in this list.

Returns
`List<? extends Adapter<? extends RecyclerView.ViewHolder>>`	A copy of the list of adapters in this ConcatAdapter.

getItemCount

public 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

public long getItemId (int position)

Return the stable ID for the item at position. If hasStableIds() would return false this method should return RecyclerView.NO_ID. The default implementation of this method returns RecyclerView.NO_ID.

Parameters
`position`	`int`: Adapter position to query

Returns
`long`	the stable ID of the item at position

getItemViewType

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
`position`	`int`: 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.

public void onAttachedToRecyclerView (RecyclerView recyclerView)

Called by RecyclerView when it starts observing this Adapter.

Keep in mind that same adapter may be observed by multiple RecyclerViews.

Parameters
`recyclerView`	`RecyclerView`: The RecyclerView instance which started observing this adapter.

public void onBindViewHolder (RecyclerView.ViewHolder holder, 
                int position)

Called by RecyclerView to display the data at the specified position. This method should update the contents of the RecyclerView.ViewHolder.itemView to reflect the item at the given position.

Note that unlike ListView, 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 RecyclerView.ViewHolder.getBindingAdapterPosition() which will have the updated adapter position. Override onBindViewHolder(ViewHolder, int, List) instead if Adapter can handle efficient partial bind.

Parameters
`holder`	`RecyclerView.ViewHolder`: The ViewHolder which should be updated to represent the contents of the item at the given position in the data set.
`position`	`int`: The position of the item within the adapter's data set.

onCreateViewHolder

public RecyclerView.ViewHolder onCreateViewHolder (ViewGroup parent, 
                int viewType)

Called when RecyclerView needs a new 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 onBindViewHolder(ViewHolder, int, 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 View.findViewById(int) calls.

Parameters
`parent`	`ViewGroup`: The ViewGroup into which the new View will be added after it is bound to an adapter position.
`viewType`	`int`: The view type of the new View.

Returns
`RecyclerView.ViewHolder`	A new ViewHolder that holds a View of the given view type.

public void onDetachedFromRecyclerView (RecyclerView recyclerView)

Called by RecyclerView when it stops observing this Adapter.

Parameters
`recyclerView`	`RecyclerView`: The RecyclerView instance which stopped observing this adapter.

public boolean onFailedToRecycleView (RecyclerView.ViewHolder 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 onBindViewHolder(ViewHolder, 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 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 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
`holder`	`RecyclerView.ViewHolder`: 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.

public void onViewAttachedToWindow (RecyclerView.ViewHolder 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 onViewDetachedFromWindow those resources should be restored here.

Parameters
`holder`	`RecyclerView.ViewHolder`: Holder of the view being attached

public void onViewDetachedFromWindow (RecyclerView.ViewHolder 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
`holder`	`RecyclerView.ViewHolder`: Holder of the view being detached

public void onViewRecycled (RecyclerView.ViewHolder holder)

Called when a view created by this adapter has been recycled.

A view is recycled when a RecyclerView.LayoutManager decides that it no longer needs to be attached to its parent 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 RecyclerView.ViewHolder.getBindingAdapterPosition() to get its adapter position.

Parameters
`holder`	`RecyclerView.ViewHolder`: The ViewHolder for the view being recycled

public boolean removeAdapter (Adapter<? extends RecyclerView.ViewHolder> adapter)

Removes the given adapter from the adapters list if it exists

Parameters
`adapter`	`Adapter`: The adapter to remove

Returns
`boolean`	`true` if the adapter was previously added to this `ConcatAdapter` and now removed or `false` if it couldn't be found.

setHasStableIds

public void setHasStableIds (boolean hasStableIds)

Calling this method is an error and will result in an UnsupportedOperationException. You should use the ConcatAdapter.Config object passed into the ConcatAdapter to configure this behavior.

Parameters
`hasStableIds`	`boolean`: Whether items in data set have unique identifiers or not.

public void setStateRestorationPolicy (RecyclerView.Adapter.StateRestorationPolicy strategy)

Calling this method is an error and will result in an UnsupportedOperationException. ConcatAdapter infers this value from added RecyclerView.Adapters.

Parameters
`strategy`	`RecyclerView.Adapter.StateRestorationPolicy`: The saved state restoration strategy for this Adapter such that `ConcatAdapter` will allow state restoration only if all added adapters allow it or there are no adapters.

ConcatAdapter

Summary

Nested classes

Public constructors

Public methods

Inherited methods

Public constructors

ConcatAdapter

ConcatAdapter

ConcatAdapter

ConcatAdapter

Public methods

addAdapter

addAdapter

findRelativeAdapterPositionIn

getAdapters

getItemCount

getItemId

getItemViewType

onAttachedToRecyclerView

onBindViewHolder

onCreateViewHolder

onDetachedFromRecyclerView

onFailedToRecycleView

onViewAttachedToWindow

onViewDetachedFromWindow

onViewRecycled

removeAdapter

setHasStableIds

setStateRestorationPolicy