1 /* 2 * Copyright (C) 2008 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 /** 20 * Interface that should be implemented on Adapters to enable fast scrolling 21 * in an {@link AbsListView} between sections of the list. A section is a group of list items 22 * to jump to that have something in common. For example, they may begin with the 23 * same letter or they may be songs from the same artist. 24 */ 25 public interface SectionIndexer { 26 /** 27 * This provides the list view with an array of section objects. In the simplest 28 * case these are Strings, each containing one letter of the alphabet. 29 * They could be more complex objects that indicate the grouping for the adapter's 30 * consumption. The list view will call toString() on the objects to get the 31 * preview letter to display while scrolling. 32 * @return the array of objects that indicate the different sections of the list. 33 */ 34 Object[] getSections(); 35 36 /** 37 * Provides the starting index in the list for a given section. 38 * @param section the index of the section to jump to. 39 * @return the starting position of that section. If the section is out of bounds, the 40 * position must be clipped to fall within the size of the list. 41 */ 42 int getPositionForSection(int section); 43 44 /** 45 * This is a reverse mapping to fetch the section index for a given position 46 * in the list. 47 * @param position the position for which to return the section 48 * @return the section index. If the position is out of bounds, the section index 49 * must be clipped to fall within the size of the section array. 50 */ 51 int getSectionForPosition(int position); 52 } 53
