belongs to Maven artifact com.android.support:recyclerview-v7:28.0.0-alpha1
DiffUtil.ItemCallback
public
static
abstract
class
DiffUtil.ItemCallback
extends Object
| java.lang.Object | |
| ↳ | android.support.v7.util.DiffUtil.ItemCallback<T> |
Callback for calculating the diff between two non-null items in a list.
DiffUtil.Callback serves two roles - list indexing, and item diffing. ItemCallback handles
just the second of these, which allows separation of code that indexes into an array or List
from the presentation-layer and content specific diffing code.
Summary
Public constructors | |
|---|---|
DiffUtil.ItemCallback()
|
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Public methods | |
|---|---|
abstract
boolean
|
areContentsTheSame(T oldItem, T newItem)
Called to check whether two items have the same data. |
abstract
boolean
|
areItemsTheSame(T oldItem, T newItem)
Called to check whether two objects represent the same item. |
Object
|
getChangePayload(T oldItem, T newItem)
When |
Inherited methods | |
|---|---|
From
class
java.lang.Object
| |
Public constructors
Public methods
areContentsTheSame
boolean areContentsTheSame (T oldItem,
T newItem)
Called to check whether two items have the same data.
This information is used to detect if the contents of an item have changed.
This method to check equality instead of equals(Object) so that you can
change its behavior depending on your UI.
For example, if you are using DiffUtil with a
RecyclerView.Adapter, you should
return whether the items' visual representations are the same.
This method is called only if areItemsTheSame(T, T) returns true for
these items.
Note: Two null items are assumed to represent the same contents. This callback
will not be invoked for this case.
| Parameters | |
|---|---|
oldItem |
T: The item in the old list. |
newItem |
T: The item in the new list. |
| Returns | |
|---|---|
boolean |
True if the contents of the items are the same or false if they are different. |
See also:
areItemsTheSame
boolean areItemsTheSame (T oldItem,
T newItem)
Called to check whether two objects represent the same item.
For example, if your items have unique ids, this method should check their id equality.
Note: null items in the list are assumed to be the same as another null
item and are assumed to not be the same as a non-null item. This callback will
not be invoked for either of those cases.
| Parameters | |
|---|---|
oldItem |
T: The item in the old list. |
newItem |
T: The item in the new list. |
| Returns | |
|---|---|
boolean |
True if the two items represent the same object or false if they are different. |
See also:
getChangePayload
Object getChangePayload (T oldItem,
T newItem)
When areItemsTheSame(T, T) returns true for two items and
areContentsTheSame(T, T) returns false for them, this method is called to
get a payload about the change.
For example, if you are using DiffUtil with RecyclerView, you can return the
particular field that changed in the item and your
ItemAnimator can use that
information to run the correct animation.
Default implementation returns null.
| Parameters | |
|---|---|
oldItem |
T |
newItem |
T |
| Returns | |
|---|---|
Object |
|
See also: