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 17 package android.webkit; 18 19 import android.annotation.Nullable; 20 21 import 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 */ 28 public 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 getCurrentItem()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 */ getCurrentIndex()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 */ getItemAtIndex(int index)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 */ getSize()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. On Android 4.4 and later there is no need to use 61 * this, as the object is already a read-only copy of the internal state. 62 */ clone()63 protected abstract WebBackForwardList clone(); 64 } 65