belongs to Maven artifact com.android.support:recyclerview-v7:28.0.0-alpha1
RecyclerView.Adapter
public
static
abstract
class
RecyclerView.Adapter
extends Object
| java.lang.Object | |
| ↳ | android.support.v7.widget.RecyclerView.Adapter<VH extends android.support.v7.widget.RecyclerView.ViewHolder> |
Known Direct Subclasses
|
Base class for an Adapter
Adapters provide a binding from an app-specific data set to views that are displayed
within a RecyclerView.
Summary
Public constructors | |
|---|---|
RecyclerView.Adapter()
|
|
Public methods | |
|---|---|
final
void
|
bindViewHolder(VH holder, int position)
This method internally calls |
final
VH
|
createViewHolder(ViewGroup parent, int viewType)
This method calls |
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 |
int
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getItemViewType(int position)
Return the view type of the item at |
final
boolean
|
hasObservers()
Returns true if one or more observers are attached to this adapter. |
final
boolean
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hasStableIds()
Returns true if this adapter publishes a unique |
final
void
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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 |
final
void
|
notifyItemChanged(int position)
Notify any registered observers that the item at |
final
void
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notifyItemInserted(int position)
Notify any registered observers that the item reflected at |
final
void
|
notifyItemMoved(int fromPosition, int toPosition)
Notify any registered observers that the item reflected at |
final
void
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notifyItemRangeChanged(int positionStart, int itemCount, Object payload)
Notify any registered observers that the |
final
void
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notifyItemRangeChanged(int positionStart, int itemCount)
Notify any registered observers that the |
final
void
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notifyItemRangeInserted(int positionStart, int itemCount)
Notify any registered observers that the currently reflected |
final
void
|
notifyItemRangeRemoved(int positionStart, int itemCount)
Notify any registered observers that the |
final
void
|
notifyItemRemoved(int position)
Notify any registered observers that the item previously located at |
void
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onAttachedToRecyclerView(RecyclerView recyclerView)
Called by RecyclerView when it starts observing this Adapter. |
abstract
void
|
onBindViewHolder(VH holder, int position)
Called by RecyclerView to display the data at the specified position. |
void
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onBindViewHolder(VH holder, int position, List<Object> payloads)
Called by RecyclerView to display the data at the specified position. |
abstract
VH
|
onCreateViewHolder(ViewGroup parent, int viewType)
Called when RecyclerView needs a new |
void
|
onDetachedFromRecyclerView(RecyclerView recyclerView)
Called by RecyclerView when it stops observing this Adapter. |
boolean
|
onFailedToRecycleView(VH holder)
Called by the RecyclerView if a ViewHolder created by this Adapter cannot be recycled due to its transient state. |
void
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onViewAttachedToWindow(VH holder)
Called when a view created by this adapter has been attached to a window. |
void
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onViewDetachedFromWindow(VH holder)
Called when a view created by this adapter has been detached from its window. |
void
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onViewRecycled(VH holder)
Called when a view created by this adapter has been recycled. |
void
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registerAdapterDataObserver(RecyclerView.AdapterDataObserver observer)
Register a new observer to listen for data changes. |
void
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setHasStableIds(boolean hasStableIds)
Indicates whether each item in the data set can be represented with a unique identifier
of type |
void
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unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver observer)
Unregister an observer currently listening for data changes. |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
Public constructors
Public methods
bindViewHolder
void bindViewHolder (VH 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.
| Parameters | |
|---|---|
holder |
VH |
position |
int |
See also:
createViewHolder
VH 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.
| Parameters | |
|---|---|
parent |
ViewGroup |
viewType |
int |
| Returns | |
|---|---|
VH |
|
See also:
getItemCount
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
long getItemId (int position)
Return the stable ID for the item at position. If hasStableIds()
would return false this method should return NO_ID. The default implementation
of this method returns NO_ID.
| Parameters | |
|---|---|
position |
int: Adapter position to query |
| Returns | |
|---|---|
long |
the stable ID of the item at position |
getItemViewType
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.
|
hasObservers
boolean hasObservers ()
Returns true if one or more observers are attached to this adapter.
| Returns | |
|---|---|
boolean |
true if this adapter has observers |
hasStableIds
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
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 stable IDs 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.
notifyItemChanged
void notifyItemChanged (int position,
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 onBindViewHolder(ViewHolder, int, 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
onBindViewHolder(ViewHolder, int, 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 | |
|---|---|
position |
int: Position of the item that has changed |
payload |
Object: Optional parameter, use null to identify a "full" update |
See also:
notifyItemChanged
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 | |
|---|---|
position |
int: Position of the item that has changed |
See also:
notifyItemInserted
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 po