Java tutorial
/* * Copyright (C) 2007 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 that links a {@link ExpandableListView} with the underlying * data. The implementation of this interface will provide access * to the data of the children (categorized by groups), and also instantiate * {@link View}s for children and groups. */ public interface ExpandableListAdapter { /** * @see Adapter#registerDataSetObserver(DataSetObserver) */ void registerDataSetObserver(DataSetObserver observer); /** * @see Adapter#unregisterDataSetObserver(DataSetObserver) */ void unregisterDataSetObserver(DataSetObserver observer); /** * Gets the number of groups. * * @return the number of groups */ int getGroupCount(); /** * Gets the number of children in a specified group. * * @param groupPosition the position of the group for which the children * count should be returned * @return the children count in the specified group */ int getChildrenCount(int groupPosition); /** * Gets the data associated with the given group. * * @param groupPosition the position of the group * @return the data child for the specified group */ Object getGroup(int groupPosition); /** * Gets the data associated with the given child within the given group. * * @param groupPosition the position of the group that the child resides in * @param childPosition the position of the child with respect to other * children in the group * @return the data of the child */ Object getChild(int groupPosition, int childPosition); /** * Gets the ID for the group at the given position. This group ID must be * unique across groups. The combined ID (see * {@link #getCombinedGroupId(long)}) must be unique across ALL items * (groups and all children). * * @param groupPosition the position of the group for which the ID is wanted * @return the ID associated with the group */ long getGroupId(int groupPosition); /** * Gets the ID for the given child within the given group. This ID must be * unique across all children within the group. The combined ID (see * {@link #getCombinedChildId(long, long)}) must be unique across ALL items * (groups and all children). * * @param groupPosition the position of the group that contains the child * @param childPosition the position of the child within the group for which * the ID is wanted * @return the ID associated with the child */ long getChildId(int groupPosition, int childPosition); /** * Indicates whether the child and group IDs are stable across changes to the * underlying data. * * @return whether or not the same ID always refers to the same object * @see Adapter#hasStableIds() */ boolean hasStableIds(); /** * Gets a View that displays the given group. This View is only for the * group--the Views for the group's children will be fetched using * {@link #getChildView(int, int, boolean, View, ViewGroup)}. * * @param groupPosition the position of the group for which the View is * returned * @param isExpanded whether the group is expanded or collapsed * @param convertView the old view to reuse, if possible. 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. It is not * guaranteed that the convertView will have been previously * created by * {@link #getGroupView(int, boolean, View, ViewGroup)}. * @param parent the parent that this view will eventually be attached to * @return the View corresponding to the group at the specified position */ View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent); /** * Gets a View that displays the data for the given child within the given * group. * * @param groupPosition the position of the group that contains the child * @param childPosition the position of the child (for which the View is * returned) within the group * @param isLastChild Whether the child is the last child within the group * @param convertView the old view to reuse, if possible. 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. It is not * guaranteed that the convertView will have been previously * created by * {@link #getChildView(int, int, boolean, View, ViewGroup)}. * @param parent the parent that this view will eventually be attached to * @return the View corresponding to the child at the specified position */ View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent); /** * Whether the child at the specified position is selectable. * * @param groupPosition the position of the group that contains the child * @param childPosition the position of the child within the group * @return whether the child is selectable. */ boolean isChildSelectable(int groupPosition, int childPosition); /** * @see ListAdapter#areAllItemsEnabled() */ boolean areAllItemsEnabled(); /** * @see ListAdapter#isEmpty() */ boolean isEmpty(); /** * Called when a group is expanded. * * @param groupPosition The group being expanded. */ void onGroupExpanded(int groupPosition); /** * Called when a group is collapsed. * * @param groupPosition The group being collapsed. */ void onGroupCollapsed(int groupPosition); /** * Gets an ID for a child that is unique across any item (either group or * child) that is in this list. Expandable lists require each item (group or * child) to have a unique ID among all children and groups in the list. * This method is responsible for returning that unique ID given a child's * ID and its group's ID. Furthermore, if {@link #hasStableIds()} is true, the * returned ID must be stable as well. * * @param groupId The ID of the group that contains this child. * @param childId The ID of the child. * @return The unique (and possibly stable) ID of the child across all * groups and children in this list. */ long getCombinedChildId(long groupId, long childId); /** * Gets an ID for a group that is unique across any item (either group or * child) that is in this list. Expandable lists require each item (group or * child) to have a unique ID among all children and groups in the list. * This method is responsible for returning that unique ID given a group's * ID. Furthermore, if {@link #hasStableIds()} is true, the returned ID must be * stable as well. * * @param groupId The ID of the group * @return The unique (and possibly stable) ID of the group across all * groups and children in this list. */ long getCombinedGroupId(long groupId); }