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Lucene example source code file (StandardFilter.java)

This example Lucene source code file (StandardFilter.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

acronym_type, acronym_type, apostrophe_type, deprecated, io, ioexception, ioexception, override, standardfilter, standardfilter, string, string, todo, tokenfilter, tokenstream

The Lucene StandardFilter.java source code

package org.apache.lucene.analysis.standard;

 * 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 java.io.IOException;

import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.Version;

 * Normalizes tokens extracted with {@link StandardTokenizer}.
public class StandardFilter extends TokenFilter {
  private final Version matchVersion;
  /** @deprecated Use {@link #StandardFilter(Version, TokenStream)} instead. */
  public StandardFilter(TokenStream in) {
    this(Version.LUCENE_30, in);
  public StandardFilter(Version matchVersion, TokenStream in) {
    this.matchVersion = matchVersion;
  private static final String APOSTROPHE_TYPE = ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.APOSTROPHE];
  private static final String ACRONYM_TYPE = ClassicTokenizer.TOKEN_TYPES[ClassicTokenizer.ACRONYM];

  // this filters uses attribute type
  private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);
  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
  public final boolean incrementToken() throws IOException {
    if (matchVersion.onOrAfter(Version.LUCENE_31))
      return input.incrementToken(); // TODO: add some niceties for the new grammar
      return incrementTokenClassic();
  public final boolean incrementTokenClassic() throws IOException {
    if (!input.incrementToken()) {
      return false;

    final char[] buffer = termAtt.buffer();
    final int bufferLength = termAtt.length();
    final String type = typeAtt.type();

    if (type == APOSTROPHE_TYPE &&      // remove 's
        bufferLength >= 2 &&
        buffer[bufferLength-2] == '\'' &&
        (buffer[bufferLength-1] == 's' || buffer[bufferLength-1] == 'S')) {
      // Strip last 2 characters off
      termAtt.setLength(bufferLength - 2);
    } else if (type == ACRONYM_TYPE) {      // remove dots
      int upto = 0;
      for(int i=0;i<bufferLength;i++) {
        char c = buffer[i];
        if (c != '.')
          buffer[upto++] = c;

    return true;

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene StandardFilter.java source code file:

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