Lucene example source code file (TestSegmentTermEnum.java)

This example Lucene source code file (TestSegmentTermEnum.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

document, document, exception, indexwriter, indexwriter, io, ioexception, ioexception, mockanalyzer, mockanalyzer, override, segmenttermenum, term, termenum, test_version_current

The Lucene TestSegmentTermEnum.java source code

package org.apache.lucene.index;

/**
 * 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.util.LuceneTestCase;
import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.store.Directory;


public class TestSegmentTermEnum extends LuceneTestCase {
  
  Directory dir;
  
  @Override
  public void setUp() throws Exception {
    super.setUp();
    dir = newDirectory();
  }
  
  @Override
  public void tearDown() throws Exception {
    dir.close();
    super.tearDown();
  }

  public void testTermEnum() throws IOException {
    IndexWriter writer = null;

    writer  = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random)));

    // ADD 100 documents with term : aaa
    // add 100 documents with terms: aaa bbb
    // Therefore, term 'aaa' has document frequency of 200 and term 'bbb' 100
    for (int i = 0; i < 100; i++) {
      addDoc(writer, "aaa");
      addDoc(writer, "aaa bbb");
    }

    writer.close();

    // verify document frequency of terms in an unoptimized index
    verifyDocFreq();

    // merge segments by optimizing the index
    writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random)).setOpenMode(OpenMode.APPEND));
    writer.optimize();
    writer.close();

    // verify document frequency of terms in an optimized index
    verifyDocFreq();
  }

  public void testPrevTermAtEnd() throws IOException
  {
    IndexWriter writer  = new IndexWriter(dir, newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random)));
    addDoc(writer, "aaa bbb");
    writer.close();
    SegmentReader reader = SegmentReader.getOnlySegmentReader(dir);
    SegmentTermEnum termEnum = (SegmentTermEnum) reader.terms();
    assertTrue(termEnum.next());
    assertEquals("aaa", termEnum.term().text());
    assertTrue(termEnum.next());
    assertEquals("aaa", termEnum.prev().text());
    assertEquals("bbb", termEnum.term().text());
    assertFalse(termEnum.next());
    assertEquals("bbb", termEnum.prev().text());
    reader.close();
  }

  private void verifyDocFreq()
      throws IOException
  {
      IndexReader reader = IndexReader.open(dir, true);
      TermEnum termEnum = null;

    // create enumeration of all terms
    termEnum = reader.terms();
    // go to the first term (aaa)
    termEnum.next();
    // assert that term is 'aaa'
    assertEquals("aaa", termEnum.term().text());
    assertEquals(200, termEnum.docFreq());
    // go to the second term (bbb)
    termEnum.next();
    // assert that term is 'bbb'
    assertEquals("bbb", termEnum.term().text());
    assertEquals(100, termEnum.docFreq());

    termEnum.close();


    // create enumeration of terms after term 'aaa', including 'aaa'
    termEnum = reader.terms(new Term("content", "aaa"));
    // assert that term is 'aaa'
    assertEquals("aaa", termEnum.term().text());
    assertEquals(200, termEnum.docFreq());
    // go to term 'bbb'
    termEnum.next();
    // assert that term is 'bbb'
    assertEquals("bbb", termEnum.term().text());
    assertEquals(100, termEnum.docFreq());
    termEnum.close();
    reader.close();
  }

  private void addDoc(IndexWriter writer, String value) throws IOException
  {
    Document doc = new Document();
    doc.add(newField("content", value, Field.Store.NO, Field.Index.ANALYZED));
    writer.addDocument(doc);
  }
}