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Lucene example source code file (ShortFieldSource.java)

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

Java - Lucene tags/keywords

docvalues, docvalues, fieldcache, fieldcachesource, indexreader, io, ioexception, object, override, override, shortfieldsource, shortfieldsource, string, string

The Lucene ShortFieldSource.java source code

package org.apache.lucene.search.function;

 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.function.DocValues;

import java.io.IOException;

 * Expert: obtains short field values from the 
 * {@link org.apache.lucene.search.FieldCache FieldCache}
 * using <code>getShorts() and makes those values 
 * available as other numeric types, casting as needed.
 * @lucene.experimental
 * @see org.apache.lucene.search.function.FieldCacheSource for requirements 
 * on the field.
 * <p>NOTE: with the switch in 2.9 to segment-based
 * searching, if {@link #getValues} is invoked with a
 * composite (multi-segment) reader, this can easily cause
 * double RAM usage for the values in the FieldCache.  It's
 * best to switch your application to pass only atomic
 * (single segment) readers to this API.</p>
public class ShortFieldSource extends FieldCacheSource {
  private FieldCache.ShortParser parser;

   * Create a cached short field source with default string-to-short parser. 
  public ShortFieldSource(String field) {
    this(field, null);

   * Create a cached short field source with a specific string-to-short parser. 
  public ShortFieldSource(String field, FieldCache.ShortParser parser) {
    this.parser = parser;

  /*(non-Javadoc) @see org.apache.lucene.search.function.ValueSource#description() */
  public String description() {
    return "short(" + super.description() + ')';

  /*(non-Javadoc) @see org.apache.lucene.search.function.FieldCacheSource#getCachedValues(org.apache.lucene.search.FieldCache, java.lang.String, org.apache.lucene.index.IndexReader) */
  public DocValues getCachedFieldValues (FieldCache cache, String field, IndexReader reader) throws IOException {
    final short[] arr = cache.getShorts(reader, field, parser);
    return new DocValues() {
      /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#floatVal(int) */
      public float floatVal(int doc) { 
        return arr[doc];
      /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#intVal(int) */
      public  int intVal(int doc) { 
        return arr[doc]; 
      /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#toString(int) */
      public String toString(int doc) { 
        return  description() + '=' + intVal(doc);  
      /*(non-Javadoc) @see org.apache.lucene.search.function.DocValues#getInnerArray() */
      Object getInnerArray() {
        return arr;

  /*(non-Javadoc) @see org.apache.lucene.search.function.FieldCacheSource#cachedFieldSourceEquals(org.apache.lucene.search.function.FieldCacheSource) */
  public boolean cachedFieldSourceEquals(FieldCacheSource o) {
    if (o.getClass() !=  ShortFieldSource.class) {
      return false;
    ShortFieldSource other = (ShortFieldSource)o;
    return this.parser==null ? 
      other.parser==null :
      this.parser.getClass() == other.parser.getClass();

  /*(non-Javadoc) @see org.apache.lucene.search.function.FieldCacheSource#cachedFieldSourceHashCode() */
  public int cachedFieldSourceHashCode() {
    return parser==null ? 
      Short.class.hashCode() : parser.getClass().hashCode();


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