Callback
abstract class Callback<T2 : Any!> : Comparator<T2>, ListUpdateCallback
kotlin.Any | |
↳ | androidx.recyclerview.widget.SortedList.Callback |
The class that controls the behavior of the SortedList
.
It defines how items should be sorted and how duplicates should be handled.
SortedList calls the callback methods on this class to notify changes about the underlying data.
Summary
Public constructors | |
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<init>() The class that controls the behavior of the |
Public methods | |
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abstract Boolean |
areContentsTheSame(oldItem: T2, newItem: T2) Called by the SortedList when it wants to check whether two items have the same data or not. |
abstract Boolean |
areItemsTheSame(item1: T2, item2: T2) Called by the SortedList to decide whether two objects represent the same Item or not. |
abstract Int |
compare(o1: T2, o2: T2) Similar to |
open Any? |
getChangePayload(item1: T2, item2: T2) When |
abstract Unit |
Called by the SortedList when the item at the given position is updated. |
open Unit |
Inherited functions | |
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Public constructors
<init>
Callback()
The class that controls the behavior of the SortedList
.
It defines how items should be sorted and how duplicates should be handled.
SortedList calls the callback methods on this class to notify changes about the underlying data.
Public methods
areContentsTheSame
abstract fun areContentsTheSame(
oldItem: T2,
newItem: T2
): Boolean
Called by the SortedList when it wants to check whether two items have the same data or not. SortedList uses this information to decide whether it should call onChanged(int, int)
or not.
SortedList uses this method to check equality instead of Object#equals(Object)
so that you can change its behavior depending on your UI.
For example, if you are using SortedList with a RecyclerView.Adapter
, you should return whether the items' visual representations are the same or not.
Parameters | |
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oldItem |
T2: The previous representation of the object. |
newItem |
T2: The new object that replaces the previous one. |
Return | |
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Boolean |
True if the contents of the items are the same or false if they are different. |
areItemsTheSame
abstract fun areItemsTheSame(
item1: T2,
item2: T2
): Boolean
Called by the SortedList to decide whether two objects represent the same Item or not.
For example, if your items have unique ids, this method should check their equality.
Parameters | |
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item1 |
T2: The first item to check. |
item2 |
T2: The second item to check. |
Return | |
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Boolean |
True if the two items represent the same object or false if they are different. |
compare
abstract fun compare(
o1: T2,
o2: T2
): Int
Similar to java.util.Comparator#compare(Object, Object)
, should compare two and return how they should be ordered.
Parameters | |
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o1 |
T2: The first object to compare. |
o2 |
T2: The second object to compare. |
Return | |
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Int |
a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second. |
getChangePayload
@Nullable open fun getChangePayload(
item1: T2,
item2: T2
): Any?
When areItemsTheSame(T2, T2)
returns true
for two items and areContentsTheSame(T2, T2)
returns false for them, Callback
calls this method to get a payload about the change.
For example, if you are using Callback
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 | |
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item1 |
T2: The first item to check. |
item2 |
T2: The second item to check. |
Return | |
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Any? |
A payload object that represents the changes between the two items. |
onChanged
abstract fun onChanged(
position: Int,
count: Int
): Unit
Called by the SortedList when the item at the given position is updated.
Parameters | |
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position |
Int: The position of the item which has been updated. |
count |
Int: The number of items which has changed. |