1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package android.support.v7.util;
17
18/**
19 * An interface that can receive Update operations that are applied to a list.
20 * <p>
21 * This class can be used together with DiffUtil to detect changes between two lists.
22 */
23public interface ListUpdateCallback {
24    /**
25     * Called when {@code count} number of items are inserted at the given position.
26     *
27     * @param position The position of the new item.
28     * @param count    The number of items that have been added.
29     */
30    void onInserted(int position, int count);
31
32    /**
33     * Called when {@code count} number of items are removed from the given position.
34     *
35     * @param position The position of the item which has been removed.
36     * @param count    The number of items which have been removed.
37     */
38    void onRemoved(int position, int count);
39
40    /**
41     * Called when an item changes its position in the list.
42     *
43     * @param fromPosition The previous position of the item before the move.
44     * @param toPosition   The new position of the item.
45     */
46    void onMoved(int fromPosition, int toPosition);
47
48    /**
49     * Called when {@code count} number of items are updated at the given position.
50     *
51     * @param position The position of the item which has been updated.
52     * @param count    The number of items which has changed.
53     */
54    void onChanged(int position, int count, Object payload);
55}
56