SortedList.Callback

Artifact: androidx.recyclerview:recyclerview

View Source

Added in 1.0.0

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Kotlin |Java

public abstract class SortedList.Callback<T2> implements Comparator, ListUpdateCallback

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.

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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
Callback()

Public methods
abstract boolean	areContentsTheSame(T2 oldItem, T2 newItem) Called by the SortedList when it wants to check whether two items have the same data or not.
abstract boolean	areItemsTheSame(T2 item1, T2 item2) Called by the SortedList to decide whether two objects represent the same Item or not.
abstract int	compare(T2 o1, T2 o2) Similar to compare, should compare two and return how they should be ordered.
@Nullable Object	getChangePayload(T2 item1, T2 item2) When areItemsTheSame returns true for two items and areContentsTheSame returns false for them, Callback calls this method to get a payload about the change.
abstract void	onChanged(int position, int count) Called by the SortedList when the item at the given position is updated.
void	onChanged(int position, int count, Object payload) Called when count} number of items are updated at the given position.

Inherited methods
From java.util.Comparator static Comparator<T> <T, U> comparing(     Function<T, U> keyExtractor,     Comparator<U> keyComparator ) static Comparator<T> <T> comparingDouble(ToDoubleFunction<T> keyExtractor) static Comparator<T> <T> comparingInt(ToIntFunction<T> keyExtractor) static Comparator<T> <T> comparingLong(ToLongFunction<T> keyExtractor) static Comparator<T> <T extends Comparable<T>> naturalOrder() static Comparator<T> <T> nullsFirst(Comparator<T> comparator) static Comparator<T> <T> nullsLast(Comparator<T> comparator) static Comparator<T> <T extends Comparable<T>> reverseOrder() Comparator<T> reversed() Comparator<T> thenComparing(Comparator<T> other) Comparator<T> thenComparingDouble(ToDoubleFunction<T> keyExtractor) Comparator<T> thenComparingInt(ToIntFunction<T> keyExtractor) Comparator<T> thenComparingLong(ToLongFunction<T> keyExtractor)
From androidx.recyclerview.widget.ListUpdateCallback abstract void onInserted(int position, int count) Called when count number of items are inserted at the given position. abstract void onMoved(int fromPosition, int toPosition) Called when an item changes its position in the list. abstract void onRemoved(int position, int count) Called when count number of items are removed from the given position.

Public constructors

Callback

Added in 1.0.0

public Callback()

Public methods

areContentsTheSame

Added in 1.0.0

public abstract boolean areContentsTheSame(T2 oldItem, T2 newItem)

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 or not.

SortedList uses this method to check equality instead of equals 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
T2 oldItem	The previous representation of the object.
T2 newItem	The new object that replaces the previous one.

Returns
boolean	True if the contents of the items are the same or false if they are different.

areItemsTheSame

Added in 1.0.0

public abstract boolean areItemsTheSame(T2 item1, T2 item2)

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
T2 item1	The first item to check.
T2 item2	The second item to check.

Returns
boolean	True if the two items represent the same object or false if they are different.

compare

Added in 1.0.0

public abstract int compare(T2 o1, T2 o2)

Similar to compare, should compare two and return how they should be ordered.

Parameters
T2 o1	The first object to compare.
T2 o2	The second object to compare.

Returns
int	a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

getChangePayload

Added in 1.0.0

public @Nullable Object getChangePayload(T2 item1, T2 item2)

When areItemsTheSame returns true for two items and areContentsTheSame 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
T2 item1	The first item to check.
T2 item2	The second item to check.

Returns
@Nullable Object	A payload object that represents the changes between the two items.

onChanged

Added in 1.0.0

public abstract void onChanged(int position, int count)

Called by the SortedList when the item at the given position is updated.

Parameters
int position	The position of the item which has been updated.
int count	The number of items which has changed.

onChanged

Added in 1.4.0-rc01

public void onChanged(int position, int count, Object payload)

Called when count} number of items are updated at the given position.