The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 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.widget; |
| 18 | |
| 19 | import android.database.DataSetObserver; |
| 20 | import android.view.KeyEvent; |
| 21 | import android.view.View; |
| 22 | import android.view.ViewGroup; |
| 23 | |
| 24 | /** |
| 25 | * An Adapter object acts as a bridge between an {@link AdapterView} and the |
| 26 | * underlying data for that view. The Adapter provides access to the data items. |
| 27 | * The Adapter is also responsible for making a {@link android.view.View} for |
| 28 | * each item in the data set. |
| 29 | * |
| 30 | * @see android.widget.ArrayAdapter |
| 31 | * @see android.widget.CursorAdapter |
| 32 | * @see android.widget.SimpleCursorAdapter |
| 33 | */ |
| 34 | public interface Adapter { |
| 35 | /** |
| 36 | * Register an observer that is called when changes happen to the data used by this adapter. |
| 37 | * |
| 38 | * @param observer the object that gets notified when the data set changes. |
| 39 | */ |
| 40 | void registerDataSetObserver(DataSetObserver observer); |
| 41 | |
| 42 | /** |
| 43 | * Unregister an observer that has previously been registered with this |
| 44 | * adapter via {@link #registerDataSetObserver}. |
| 45 | * |
| 46 | * @param observer the object to unregister. |
| 47 | */ |
| 48 | void unregisterDataSetObserver(DataSetObserver observer); |
| 49 | |
| 50 | /** |
| 51 | * How many items are in the data set represented by this Adapter. |
| 52 | * |
| 53 | * @return Count of items. |
| 54 | */ |
| 55 | int getCount(); |
| 56 | |
| 57 | /** |
| 58 | * Get the data item associated with the specified position in the data set. |
| 59 | * |
| 60 | * @param position Position of the item whose data we want within the adapter's |
| 61 | * data set. |
| 62 | * @return The data at the specified position. |
| 63 | */ |
| 64 | Object getItem(int position); |
| 65 | |
| 66 | /** |
| 67 | * Get the row id associated with the specified position in the list. |
| 68 | * |
| 69 | * @param position The position of the item within the adapter's data set whose row id we want. |
| 70 | * @return The id of the item at the specified position. |
| 71 | */ |
| 72 | long getItemId(int position); |
| 73 | |
| 74 | /** |
| 75 | * Indicated whether the item ids are stable across changes to the |
| 76 | * underlying data. |
| 77 | * |
| 78 | * @return True if the same id always refers to the same object. |
| 79 | */ |
| 80 | boolean hasStableIds(); |
| 81 | |
| 82 | /** |
| 83 | * Get a View that displays the data at the specified position in the data set. You can either |
| 84 | * create a View manually or inflate it from an XML layout file. When the View is inflated, the |
| 85 | * parent View (GridView, ListView...) will apply default layout parameters unless you use |
| 86 | * {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)} |
| 87 | * to specify a root view and to prevent attachment to the root. |
| 88 | * |
| 89 | * @param position The position of the item within the adapter's data set of the item whose view |
| 90 | * we want. |
| 91 | * @param convertView The old view to reuse, if possible. Note: You should check that this view |
| 92 | * is non-null and of an appropriate type before using. If it is not possible to convert |
| 93 | * this view to display the correct data, this method can create a new view. |
| 94 | * @param parent The parent that this view will eventually be attached to |
| 95 | * @return A View corresponding to the data at the specified position. |
| 96 | */ |
| 97 | View getView(int position, View convertView, ViewGroup parent); |
| 98 | |
| 99 | /** |
| 100 | * An item view type that causes the {@link AdapterView} to ignore the item |
| 101 | * view. For example, this can be used if the client does not want a |
| 102 | * particular view to be given for conversion in |
| 103 | * {@link #getView(int, View, ViewGroup)}. |
| 104 | * |
| 105 | * @see #getItemViewType(int) |
| 106 | * @see #getViewTypeCount() |
| 107 | */ |
| 108 | static final int IGNORE_ITEM_VIEW_TYPE = AdapterView.ITEM_VIEW_TYPE_IGNORE; |
| 109 | |
| 110 | /** |
| 111 | * Get the type of View that will be created by {@link #getView} for the specified item. |
| 112 | * |
| 113 | * @param position The position of the item within the adapter's data set whose view type we |
| 114 | * want. |
| 115 | * @return An integer representing the type of View. Two views should share the same type if one |
| 116 | * can be converted to the other in {@link #getView}. Note: Integers must be in the |
| 117 | * range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can |
| 118 | * also be returned. |
| 119 | * @see #IGNORE_ITEM_VIEW_TYPE |
| 120 | */ |
| 121 | int getItemViewType(int position); |
| 122 | |
| 123 | /** |
| 124 | * <p> |
| 125 | * Returns the number of types of Views that will be created by |
| 126 | * {@link #getView}. Each type represents a set of views that can be |
| 127 | * converted in {@link #getView}. If the adapter always returns the same |
| 128 | * type of View for all items, this method should return 1. |
| 129 | * </p> |
| 130 | * <p> |
| 131 | * This method will only be called when when the adapter is set on the |
| 132 | * the {@link AdapterView}. |
| 133 | * </p> |
| 134 | * |
| 135 | * @return The number of types of Views that will be created by this adapter |
| 136 | */ |
| 137 | int getViewTypeCount(); |
| 138 | |
| 139 | static final int NO_SELECTION = Integer.MIN_VALUE; |
| 140 | |
| 141 | /** |
| 142 | * @return true if this adapter doesn't contain any data. This is used to determine |
| 143 | * whether the empty view should be displayed. A typical implementation will return |
| 144 | * getCount() == 0 but since getCount() includes the headers and footers, specialized |
| 145 | * adapters might want a different behavior. |
| 146 | */ |
| 147 | boolean isEmpty(); |
| 148 | } |
| 149 | |