| /* |
| * Copyright (C) 2006 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.widget; |
| |
| import android.database.DataSetObserver; |
| import android.view.View; |
| import android.view.ViewGroup; |
| |
| /** |
| * An Adapter object acts as a bridge between an {@link AdapterView} and the |
| * underlying data for that view. The Adapter provides access to the data items. |
| * The Adapter is also responsible for making a {@link android.view.View} for |
| * each item in the data set. |
| * |
| * @see android.widget.ArrayAdapter |
| * @see android.widget.CursorAdapter |
| * @see android.widget.SimpleCursorAdapter |
| */ |
| public interface Adapter { |
| /** |
| * Register an observer that is called when changes happen to the data used by this adapter. |
| * |
| * @param observer the object that gets notified when the data set changes. |
| */ |
| void registerDataSetObserver(DataSetObserver observer); |
| |
| /** |
| * Unregister an observer that has previously been registered with this |
| * adapter via {@link #registerDataSetObserver}. |
| * |
| * @param observer the object to unregister. |
| */ |
| void unregisterDataSetObserver(DataSetObserver observer); |
| |
| /** |
| * How many items are in the data set represented by this Adapter. |
| * |
| * @return Count of items. |
| */ |
| int getCount(); |
| |
| /** |
| * Get the data item associated with the specified position in the data set. |
| * |
| * @param position Position of the item whose data we want within the adapter's |
| * data set. |
| * @return The data at the specified position. |
| */ |
| Object getItem(int position); |
| |
| /** |
| * Get the row id associated with the specified position in the list. |
| * |
| * @param position The position of the item within the adapter's data set whose row id we want. |
| * @return The id of the item at the specified position. |
| */ |
| long getItemId(int position); |
| |
| /** |
| * Indicates whether the item ids are stable across changes to the |
| * underlying data. |
| * |
| * @return True if the same id always refers to the same object. |
| */ |
| boolean hasStableIds(); |
| |
| /** |
| * Get a View that displays the data at the specified position in the data set. You can either |
| * create a View manually or inflate it from an XML layout file. When the View is inflated, the |
| * parent View (GridView, ListView...) will apply default layout parameters unless you use |
| * {@link android.view.LayoutInflater#inflate(int, android.view.ViewGroup, boolean)} |
| * to specify a root view and to prevent attachment to the root. |
| * |
| * @param position The position of the item within the adapter's data set of the item whose view |
| * we want. |
| * @param convertView The old view to reuse, if possible. Note: You should check that this view |
| * is non-null and of an appropriate type before using. If it is not possible to convert |
| * this view to display the correct data, this method can create a new view. |
| * Heterogeneous lists can specify their number of view types, so that this View is |
| * always of the right type (see {@link #getViewTypeCount()} and |
| * {@link #getItemViewType(int)}). |
| * @param parent The parent that this view will eventually be attached to |
| * @return A View corresponding to the data at the specified position. |
| */ |
| View getView(int position, View convertView, ViewGroup parent); |
| |
| /** |
| * An item view type that causes the {@link AdapterView} to ignore the item |
| * view. For example, this can be used if the client does not want a |
| * particular view to be given for conversion in |
| * {@link #getView(int, View, ViewGroup)}. |
| * |
| * @see #getItemViewType(int) |
| * @see #getViewTypeCount() |
| */ |
| static final int IGNORE_ITEM_VIEW_TYPE = AdapterView.ITEM_VIEW_TYPE_IGNORE; |
| |
| /** |
| * Get the type of View that will be created by {@link #getView} for the specified item. |
| * |
| * @param position The position of the item within the adapter's data set whose view type we |
| * want. |
| * @return An integer representing the type of View. Two views should share the same type if one |
| * can be converted to the other in {@link #getView}. Note: Integers must be in the |
| * range 0 to {@link #getViewTypeCount} - 1. {@link #IGNORE_ITEM_VIEW_TYPE} can |
| * also be returned. |
| * @see #IGNORE_ITEM_VIEW_TYPE |
| */ |
| int getItemViewType(int position); |
| |
| /** |
| * <p> |
| * Returns the number of types of Views that will be created by |
| * {@link #getView}. Each type represents a set of views that can be |
| * converted in {@link #getView}. If the adapter always returns the same |
| * type of View for all items, this method should return 1. |
| * </p> |
| * <p> |
| * This method will only be called when when the adapter is set on the |
| * the {@link AdapterView}. |
| * </p> |
| * |
| * @return The number of types of Views that will be created by this adapter |
| */ |
| int getViewTypeCount(); |
| |
| static final int NO_SELECTION = Integer.MIN_VALUE; |
| |
| /** |
| * @return true if this adapter doesn't contain any data. This is used to determine |
| * whether the empty view should be displayed. A typical implementation will return |
| * getCount() == 0 but since getCount() includes the headers and footers, specialized |
| * adapters might want a different behavior. |
| */ |
| boolean isEmpty(); |
| } |
| |