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Android example source code file (SectionIndexer.java)

This example Android source code file (SectionIndexer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

object, sectionindexer

The SectionIndexer.java Android example source code

/*
 * Copyright (C) 2008 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;

/**
 * Interface that should be implemented on Adapters to enable fast scrolling 
 * in an {@link AbsListView} between sections of the list. A section is a group of list items
 * to jump to that have something in common. For example, they may begin with the
 * same letter or they may be songs from the same artist. 
 */
public interface SectionIndexer {
    /**
     * This provides the list view with an array of section objects. In the simplest
     * case these are Strings, each containing one letter of the alphabet.
     * They could be more complex objects that indicate the grouping for the adapter's
     * consumption. The list view will call toString() on the objects to get the
     * preview letter to display while scrolling.
     * @return the array of objects that indicate the different sections of the list.
     */
    Object[] getSections();
    
    /**
     * Provides the starting index in the list for a given section.
     * @param section the index of the section to jump to.
     * @return the starting position of that section. If the section is out of bounds, the
     * position must be clipped to fall within the size of the list.
     */
    int getPositionForSection(int section);
    
    /**
     * This is a reverse mapping to fetch the section index for a given position
     * in the list.
     * @param position the position for which to return the section
     * @return the section index. If the position is out of bounds, the section index
     * must be clipped to fall within the size of the section array.
     */
    int getSectionForPosition(int position);    
}

Other Android examples (source code examples)

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