Callback

Kotlin |Java

abstract class Callback<T2 : Any!> : Comparator<T2>, ListUpdateCallback

kotlin.Any
↳	androidx.recyclerview.widget.SortedList.Callback

Known Direct Subclasses SortedList.BatchedCallback, SortedListAdapterCallback SortedList.BatchedCallback A callback implementation that can batch notify events dispatched by the SortedList. SortedListAdapterCallback A SortedList.Callback implementation that can bind a SortedList to a RecyclerView.Adapter.

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
<init>() The class that controls the behavior of the SortedList.

Public methods
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 java.util.Comparator#compare(Object, Object), should compare two and return how they should be ordered.
open Any?	getChangePayload(item1: T2, item2: T2) 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.
abstract Unit	onChanged(position: Int, count: Int) Called by the SortedList when the item at the given position is updated.
open Unit	onChanged(position: Int, count: Int, payload: Any?)

Inherited functions
From class ListUpdateCallback Unit onInserted(position: Int, count: Int) Called when count number of items are inserted at the given position. Unit onMoved(fromPosition: Int, toPosition: Int) Called when an item changes its position in the list. Unit onRemoved(position: Int, count: Int) Called when count number of items are removed from the given position.

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
oldItem	T2: The previous representation of the object.
newItem	T2: The new object that replaces the previous one.

Return
Boolean	True if the contents of the items are the same or false if they are different.

areItemsTheSame

abstract fun areItemsTheSame(