1 /* 2 * Copyright (C) 2015 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 com.android.setupwizardlib.items; 18 19 /** 20 * Representation of zero or more items in a list. Each instance of ItemHierarchy should be capable 21 * of being wrapped in ItemAdapter and be displayed. 22 * 23 * For example, {@link com.android.setupwizardlib.items.Item} is a representation of a single item, 24 * typically with data provided from XML. {@link com.android.setupwizardlib.items.ItemGroup} 25 * represents a list of child item hierarchies it contains, but itself does not do any display. 26 */ 27 public interface ItemHierarchy { 28 29 /** 30 * Observer for any changes in this hierarchy. If anything updated that causes this hierarchy to 31 * show different content, this observer should be called. 32 */ 33 interface Observer { 34 /** 35 * Called when an underlying data update that can cause this hierarchy to show different 36 * content has occurred. 37 */ onChanged(ItemHierarchy itemHierarchy)38 void onChanged(ItemHierarchy itemHierarchy); 39 } 40 41 /** 42 * Register an observer to observe changes for this item hierarchy. 43 */ registerObserver(Observer observer)44 void registerObserver(Observer observer); 45 46 /** 47 * Unregister a previously registered observer. 48 */ unregisterObserver(Observer observer)49 void unregisterObserver(Observer observer); 50 51 /** 52 * @return the number of items this item hierarchy represent. 53 */ getCount()54 int getCount(); 55 56 /** 57 * Get the item at position. 58 * 59 * @param position An integer from 0 to {@link #getCount()}}, which indicates the position in 60 * this item hierarchy to get the child item. 61 * @return A representation of the item at {@code position}. Must not be {@code null}. 62 */ getItemAt(int position)63 IItem getItemAt(int position); 64 65 /** 66 * Find an item hierarchy within this hierarchy which has the given ID. Or null if no match is 67 * found. This hierarchy will be returned if our ID matches. Same restrictions for Android 68 * resource IDs apply to this ID. In fact, typically this ID is a resource ID generated from 69 * XML. 70 * 71 * @param id An ID to search for in this item hierarchy. 72 * @return An ItemHierarchy which matches the given ID. 73 */ findItemById(int id)74 ItemHierarchy findItemById(int id); 75 } 76