1/*
2 * Copyright (C) 2006 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 */
16
17package android.webkit;
18
19import android.annotation.Nullable;
20
21import java.io.Serializable;
22
23/**
24 * This class contains the back/forward list for a WebView.
25 * WebView.copyBackForwardList() will return a copy of this class used to
26 * inspect the entries in the list.
27 */
28public abstract class WebBackForwardList implements Cloneable, Serializable {
29    /**
30     * Return the current history item. This method returns {@code null} if the list is
31     * empty.
32     * @return The current history item.
33     */
34    @Nullable
35    public abstract WebHistoryItem getCurrentItem();
36
37    /**
38     * Get the index of the current history item. This index can be used to
39     * directly index into the array list.
40     * @return The current index from 0...n or -1 if the list is empty.
41     */
42    public abstract int getCurrentIndex();
43
44    /**
45     * Get the history item at the given index. The index range is from 0...n
46     * where 0 is the first item and n is the last item.
47     * @param index The index to retrieve.
48     */
49    public abstract WebHistoryItem getItemAtIndex(int index);
50
51    /**
52     * Get the total size of the back/forward list.
53     * @return The size of the list.
54     */
55    public abstract int getSize();
56
57    /**
58     * Clone the entire object to be used in the UI thread by clients of
59     * WebView. This creates a copy that should never be modified by any of the
60     * webkit package classes.
61     */
62    protected abstract WebBackForwardList clone();
63}
64