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Lucene example source code file (GermanLightStemFilter.java)

This example Lucene source code file (GermanLightStemFilter.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

chartermattribute, germanlightstemfilter, germanlightstemfilter, germanlightstemmer, germanlightstemmer, io, ioexception, ioexception, keywordattribute, keywordattribute, override, tokenfilter

The Lucene GermanLightStemFilter.java source code

package org.apache.lucene.analysis.de;

/**
 * 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.IOException;

import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.KeywordMarkerFilter;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;

/**
 * A {@link TokenFilter} that applies {@link GermanLightStemmer} to stem German
 * words.
 * <p>
 * To prevent terms from being stemmed use an instance of
 * {@link KeywordMarkerFilter} or a custom {@link TokenFilter} that sets
 * the {@link KeywordAttribute} before this {@link TokenStream}.
 * </p>
 */
public final class GermanLightStemFilter extends TokenFilter {
  private final GermanLightStemmer stemmer = new GermanLightStemmer();
  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
  private final KeywordAttribute keywordAttr = addAttribute(KeywordAttribute.class);

  public GermanLightStemFilter(TokenStream input) {
    super(input);
  }
  
  @Override
  public boolean incrementToken() throws IOException {
    if (input.incrementToken()) {
      if (!keywordAttr.isKeyword()) {
        final int newlen = stemmer.stem(termAtt.buffer(), termAtt.length());
        termAtt.setLength(newlen);
      }
      return true;
    } else {
      return false;
    }
  }
}

Other Lucene examples (source code examples)

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