public
static
abstract
class
RecyclerView.ViewHolder
extends Object
| java.lang.Object | |
| ↳ | android.support.v7.widget.RecyclerView.ViewHolder |
 Known Direct Subclasses
|
A ViewHolder describes an item view and metadata about its place within the RecyclerView.
RecyclerView.Adapter implementations should subclass ViewHolder and add fields for caching
potentially expensive findViewById(int) results.
While RecyclerView.LayoutParams belong to the RecyclerView.LayoutManager,
ViewHolders belong to the adapter. Adapters should feel free to use
their own custom ViewHolder implementations to store data that makes binding view contents
easier. Implementations should assume that individual item views will hold strong references
to ViewHolder objects and that RecyclerView instances may hold
strong references to extra off-screen item views for caching purposes
Fields | |
|---|---|
public
final
View |
itemView
|
Public constructors | |
|---|---|
RecyclerView.ViewHolder(View itemView)
|
|
Public methods | |
|---|---|
final
int
|
getAdapterPosition()
Returns the Adapter position of the item represented by this ViewHolder. |
final
long
|
getItemId()
Returns The itemId represented by this ViewHolder. |
final
int
|
getItemViewType()
|
final
int
|
getLayoutPosition()
Returns the position of the ViewHolder in terms of the latest layout pass. |
final
int
|
getOldPosition()
When LayoutManager supports animations, RecyclerView tracks 3 positions for ViewHolders to perform animations. |
final
int
|
getPosition()
This method is deprecated.
This method is deprecated because its meaning is ambiguous due to the async
handling of adapter updates. Please use |
final
boolean
|
isRecyclable()
|
final
void
|
setIsRecyclable(boolean recyclable)
Informs the recycler whether this item can be recycled. |
String
|
toString()
Returns a string representation of the object. |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
int getAdapterPosition ()
Returns the Adapter position of the item represented by this ViewHolder.
Note that this might be different than the getLayoutPosition() if there are
pending adapter updates but a new layout pass has not happened yet.
RecyclerView does not handle any adapter updates until the next layout traversal. This may create temporary inconsistencies between what user sees on the screen and what adapter contents have. This inconsistency is not important since it will be less than 16ms but it might be a problem if you want to use ViewHolder position to access the adapter. Sometimes, you may need to get the exact adapter position to do some actions in response to user events. In that case, you should use this method which will calculate the Adapter position of the ViewHolder.
Note that if you've called notifyDataSetChanged(), until the
next layout pass, the return value of this method will be NO_POSITION.
| Returns | |
|---|---|
int |
The adapter position of the item if it still exists in the adapter.
NO_POSITION if item has been removed from the adapter,
notifyDataSetChanged() has been called after the last
layout pass or the ViewHolder has already been recycled.
|
long getItemId ()
Returns The itemId represented by this ViewHolder.
| Returns | |
|---|---|
long |
The the item's id if adapter has stable ids, NO_ID
otherwise
|
int getItemViewType ()
| Returns | |
|---|---|
int |
The view type of this ViewHolder. |
int getLayoutPosition ()
Returns the position of the ViewHolder in terms of the latest layout pass.
This position is mostly used by RecyclerView components to be consistent while RecyclerView lazily processes adapter updates.
For performance and animation reasons, RecyclerView batches all adapter updates until the next layout pass. This may cause mismatches between the Adapter position of the item and the position it had in the latest layout calculations.
LayoutManagers should always call this method while doing calculations based on item
positions. All methods in RecyclerView.LayoutManager, RecyclerView.State,
RecyclerView.Recycler that receive a position expect it to be the layout position
of the item.
If LayoutManager needs to call an external method that requires the adapter position of
the item, it can use getAdapterPosition() or
convertPreLayoutPositionToPostLayout(int).
| Returns | |
|---|---|
int |
Returns the adapter position of the ViewHolder in the latest layout pass. |
See also:
int getOldPosition ()
When LayoutManager supports animations, RecyclerView tracks 3 positions for ViewHolders to perform animations.
If a ViewHolder was laid out in the previous onLayout call, old position will keep its adapter index in the previous layout.
| Returns | |
|---|---|
int |
The previous adapter index of the Item represented by this ViewHolder or
NO_POSITION if old position does not exists or cleared (pre-layout is
complete).
|
int getPosition ()
This method is deprecated.
This method is deprecated because its meaning is ambiguous due to the async
handling of adapter updates. Please use getLayoutPosition() or
getAdapterPosition() depending on your use case.
| Returns | |
|---|---|
int |
|
See also:
boolean isRecyclable ()
| Returns | |
|---|---|
boolean |
true if this item is available to be recycled, false otherwise. |
void setIsRecyclable (boolean recyclable)
Informs the recycler whether this item can be recycled. Views which are not recyclable will not be reused for other items until setIsRecyclable() is later set to true. Calls to setIsRecyclable() should always be paired (one call to setIsRecyclabe(false) should always be matched with a later call to setIsRecyclable(true)). Pairs of calls may be nested, as the state is internally reference-counted.
| Parameters | |
|---|---|
recyclable |
boolean:
Whether this item is available to be recycled. Default value
is true.
|
String toString ()
Returns a string representation of the object. In general, the
toString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
| Returns | |
|---|---|
String |
a string representation of the object. |
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