Lucene example source code file (TestGermanStemFilter.java)

This example Lucene source code file (TestGermanStemFilter.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

analyzer, exception, exception, germanstemfilter, inputstream, io, override, reader, reader, reusableanalyzerbase, reusableanalyzerbase, testgermanstemfilter, tokenizer, tokenstreamcomponents, tokenstreamcomponents

The Lucene TestGermanStemFilter.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.InputStream;
import java.io.Reader;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.BaseTokenStreamTestCase;
import org.apache.lucene.analysis.KeywordTokenizer;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.ReusableAnalyzerBase;

import static org.apache.lucene.analysis.VocabularyAssert.*;

/**
 * Test the German stemmer. The stemming algorithm is known to work less 
 * than perfect, as it doesn't use any word lists with exceptions. We 
 * also check some of the cases where the algorithm is wrong.
 *
 */
public class TestGermanStemFilter extends BaseTokenStreamTestCase {
  Analyzer analyzer = new ReusableAnalyzerBase() {
    @Override
    protected TokenStreamComponents createComponents(String fieldName,
        Reader reader) {
      Tokenizer t = new KeywordTokenizer(reader);
      return new TokenStreamComponents(t,
          new GermanStemFilter(new LowerCaseFilter(TEST_VERSION_CURRENT, t)));
    }
  };

  public void testStemming() throws Exception {  
    InputStream vocOut = getClass().getResourceAsStream("data.txt");
    assertVocabulary(analyzer, vocOut);
    vocOut.close();
  }
  
  // LUCENE-3043: we use keywordtokenizer in this test,
  // so ensure the stemmer does not crash on zero-length strings.
  public void testEmpty() throws Exception {
    assertAnalyzesTo(analyzer, "", new String[] { "" });
  }
  
  /** blast some random strings through the analyzer */
  public void testRandomStrings() throws Exception {
    checkRandomData(random, analyzer, 10000*RANDOM_MULTIPLIER);
  }
}