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Lucene example source code file (LowerCaseTokenizer.java)

This example Lucene source code file (LowerCaseTokenizer.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

attributefactory, attributesource, attributesource, deprecated, deprecated, io, lettertokenizer, lowercasetokenizer, lowercasetokenizer, override, reader, reader

The Lucene LowerCaseTokenizer.java source code

package org.apache.lucene.analysis;

/**
 * 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,
 * 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.
 */

import java.io.Reader;

import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.Version;

/**
 * LowerCaseTokenizer performs the function of LetterTokenizer
 * and LowerCaseFilter together.  It divides text at non-letters and converts
 * them to lower case.  While it is functionally equivalent to the combination
 * of LetterTokenizer and LowerCaseFilter, there is a performance advantage
 * to doing the two tasks at once, hence this (redundant) implementation.
 * <P>
 * Note: this does a decent job for most European languages, but does a terrible
 * job for some Asian languages, where words are not separated by spaces.
 * </p>
 * <p>
 * <a name="version"/>
 * You must specify the required {@link Version} compatibility when creating
 * {@link LowerCaseTokenizer}:
 * <ul>
 * <li>As of 3.1, {@link CharTokenizer} uses an int based API to normalize and
 * detect token characters. See {@link CharTokenizer#isTokenChar(int)} and
 * {@link CharTokenizer#normalize(int)} for details.</li>
 * </ul>
 * </p>
 */
public final class LowerCaseTokenizer extends LetterTokenizer {
  
  /**
   * Construct a new LowerCaseTokenizer.
   * 
   * @param matchVersion
   *          Lucene version to match See {@link <a href="#version">above}
   * 
   * @param in
   *          the input to split up into tokens
   */
  public LowerCaseTokenizer(Version matchVersion, Reader in) {
    super(matchVersion, in);
  }

  /** 
   * Construct a new LowerCaseTokenizer using a given {@link AttributeSource}.
   *
   * @param matchVersion
   *          Lucene version to match See {@link <a href="#version">above}
   * @param source
   *          the attribute source to use for this {@link Tokenizer}
   * @param in
   *          the input to split up into tokens
   */
  public LowerCaseTokenizer(Version matchVersion, AttributeSource source, Reader in) {
    super(matchVersion, source, in);
  }

  /**
   * Construct a new LowerCaseTokenizer using a given
   * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
   *
   * @param matchVersion
   *          Lucene version to match See {@link <a href="#version">above}
   * @param factory
   *          the attribute factory to use for this {@link Tokenizer}
   * @param in
   *          the input to split up into tokens
   */
  public LowerCaseTokenizer(Version matchVersion, AttributeFactory factory, Reader in) {
    super(matchVersion, factory, in);
  }
  
  /**
   * Construct a new LowerCaseTokenizer.
   * 
   * @deprecated use {@link #LowerCaseTokenizer(Reader)} instead. This will be
   *             removed in Lucene 4.0.
   */
  @Deprecated
  public LowerCaseTokenizer(Reader in) {
    super(Version.LUCENE_30, in);
  }

  /**
   * Construct a new LowerCaseTokenizer using a given {@link AttributeSource}.
   * 
   * @deprecated use {@link #LowerCaseTokenizer(AttributeSource, Reader)}
   *             instead. This will be removed in Lucene 4.0.
   */
  @Deprecated
  public LowerCaseTokenizer(AttributeSource source, Reader in) {
    super(Version.LUCENE_30, source, in);
  }

  /**
   * Construct a new LowerCaseTokenizer using a given
   * {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
   * 
   * @deprecated use {@link #LowerCaseTokenizer(AttributeSource.AttributeFactory, Reader)}
   *             instead. This will be removed in Lucene 4.0.
   */
  @Deprecated
  public LowerCaseTokenizer(AttributeFactory factory, Reader in) {
    super(Version.LUCENE_30, factory, in);
  }
  
  /** Converts char to lower case
   * {@link Character#toLowerCase(int)}.*/
  @Override
  protected int normalize(int c) {
    return Character.toLowerCase(c);
  }
}

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