DiffResult
open class DiffResult
kotlin.Any | |
↳ | androidx.recyclerview.widget.DiffUtil.DiffResult |
This class holds the information about the result of a DiffUtil#calculateDiff(Callback, boolean)
call.
You can consume the updates in a DiffResult via dispatchUpdatesTo(ListUpdateCallback)
or directly stream the results into a RecyclerView.Adapter
via dispatchUpdatesTo(RecyclerView.Adapter)
.
Summary
Constants | |
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static Int |
Signifies an item not present in the list. |
Public methods | |
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open Int |
convertNewPositionToOld(@IntRange(0) newListPosition: Int) Given a position in the new list, returns the position in the old list, or |
open Int |
convertOldPositionToNew(@IntRange(0) oldListPosition: Int) Given a position in the old list, returns the position in the new list, or |
open Unit |
dispatchUpdatesTo(@NonNull adapter: RecyclerView.Adapter<RecyclerView.ViewHolder!>) Dispatches the update events to the given adapter. |
open Unit |
dispatchUpdatesTo(@NonNull updateCallback: ListUpdateCallback) Dispatches update operations to the given Callback. |
Constants
Public methods
convertNewPositionToOld
open fun convertNewPositionToOld(@IntRange(0) newListPosition: Int): Int
Given a position in the new list, returns the position in the old list, or NO_POSITION
if it was removed.
Parameters | |
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newListPosition |
Int: Position of item in new list |
Return | |
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Int |
Position of item in old list, or NO_POSITION if not present. |
convertOldPositionToNew
open fun convertOldPositionToNew(@IntRange(0) oldListPosition: Int): Int
Given a position in the old list, returns the position in the new list, or NO_POSITION
if it was removed.
Parameters | |
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oldListPosition |
Int: Position of item in old list |
Return | |
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Int |
Position of item in new list, or NO_POSITION if not present. |
dispatchUpdatesTo
open fun dispatchUpdatesTo(@NonNull adapter: RecyclerView.Adapter<RecyclerView.ViewHolder!>): Unit
Dispatches the update events to the given adapter.
For example, if you have an Adapter
that is backed by a List
, you can swap the list with the new one then call this method to dispatch all updates to the RecyclerView.
List oldList = mAdapter.getData(); DiffResult result = DiffUtil.calculateDiff(new MyCallback(oldList, newList)); mAdapter.setData(newList); result.dispatchUpdatesTo(mAdapter);
Note that the RecyclerView requires you to dispatch adapter updates immediately when you change the data (you cannot defer notify*
calls). The usage above adheres to this rule because updates are sent to the adapter right after the backing data is changed, before RecyclerView tries to read it.
On the other hand, if you have another AdapterDataObserver
that tries to process events synchronously, this may confuse that observer because the list is instantly moved to its final state while the adapter updates are dispatched later on, one by one. If you have such an AdapterDataObserver
, you can use dispatchUpdatesTo(ListUpdateCallback)
to handle each modification manually.
Parameters | |
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adapter |
RecyclerView.Adapter<RecyclerView.ViewHolder!>: A RecyclerView adapter which was displaying the old list and will start displaying the new list. |
See Also
dispatchUpdatesTo
open fun dispatchUpdatesTo(@NonNull updateCallback: ListUpdateCallback): Unit
Dispatches update operations to the given Callback.
These updates are atomic such that the first update call affects every update call that comes after it (the same as RecyclerView).
Parameters | |
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updateCallback |
ListUpdateCallback: The callback to receive the update operations. |