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Lucene example source code file (TestElevationComparator.java)

This example Lucene source code file (TestElevationComparator.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

booleanquery, booleanquery, document, elevationcomparatorsource, io, ioexception, ioexception, map, override, override, sortfield, string, string, termquery, throwable, util

The Lucene TestElevationComparator.java source code

package org.apache.lucene.search;

 * 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 org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.*;
import org.apache.lucene.search.FieldValueHitQueue.Entry;
import org.apache.lucene.store.*;
import org.apache.lucene.util.LuceneTestCase;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class TestElevationComparator extends LuceneTestCase {

  private final Map<String,Integer> priority = new HashMap();

  public void testSorting() throws Throwable {
    Directory directory = newDirectory();
    IndexWriter writer = new IndexWriter(
        newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random)).
    writer.addDocument(adoc(new String[] {"id", "a", "title", "ipod", "str_s", "a"}));
    writer.addDocument(adoc(new String[] {"id", "b", "title", "ipod ipod", "str_s", "b"}));
    writer.addDocument(adoc(new String[] {"id", "c", "title", "ipod ipod ipod", "str_s","c"}));
    writer.addDocument(adoc(new String[] {"id", "x", "title", "boosted", "str_s", "x"}));
    writer.addDocument(adoc(new String[] {"id", "y", "title", "boosted boosted", "str_s","y"}));
    writer.addDocument(adoc(new String[] {"id", "z", "title", "boosted boosted boosted","str_s", "z"}));

    IndexReader r = IndexReader.open(writer, true);

    IndexSearcher searcher = newSearcher(r);

    runTest(searcher, true);
    runTest(searcher, false);


  private void runTest(IndexSearcher searcher, boolean reversed) throws Throwable {

    BooleanQuery newq = new BooleanQuery(false);
    TermQuery query = new TermQuery(new Term("title", "ipod"));

    newq.add(query, BooleanClause.Occur.SHOULD);
    newq.add(getElevatedQuery(new String[] {"id", "a", "id", "x"}), BooleanClause.Occur.SHOULD);

    Sort sort = new Sort(
        new SortField("id", new ElevationComparatorSource(priority), false),
        new SortField(null, SortField.SCORE, reversed)

    TopDocsCollector<Entry> topCollector = TopFieldCollector.create(sort, 50, false, true, true, true);
    searcher.search(newq, null, topCollector);

    TopDocs topDocs = topCollector.topDocs(0, 10);
    int nDocsReturned = topDocs.scoreDocs.length;

    assertEquals(4, nDocsReturned);

    // 0 & 3 were elevated
    assertEquals(0, topDocs.scoreDocs[0].doc);
    assertEquals(3, topDocs.scoreDocs[1].doc);

    if (reversed) {
      assertEquals(2, topDocs.scoreDocs[2].doc);
      assertEquals(1, topDocs.scoreDocs[3].doc);
    } else {
      assertEquals(1, topDocs.scoreDocs[2].doc);
      assertEquals(2, topDocs.scoreDocs[3].doc);

    for (int i = 0; i < nDocsReturned; i++) {
     ScoreDoc scoreDoc = topDocs.scoreDocs[i];
     ids[i] = scoreDoc.doc;
     scores[i] = scoreDoc.score;
     documents[i] = searcher.doc(ids[i]);
     System.out.println("ids[i] = " + ids[i]);
     System.out.println("documents[i] = " + documents[i]);
     System.out.println("scores[i] = " + scores[i]);

 private Query getElevatedQuery(String[] vals) {
   BooleanQuery q = new BooleanQuery(false);
   int max = (vals.length / 2) + 5;
   for (int i = 0; i < vals.length - 1; i += 2) {
     q.add(new TermQuery(new Term(vals[i], vals[i + 1])), BooleanClause.Occur.SHOULD);
     priority.put(vals[i + 1], Integer.valueOf(max--));
     // System.out.println(" pri doc=" + vals[i+1] + " pri=" + (1+max));
   return q;

 private Document adoc(String[] vals) {
   Document doc = new Document();
   for (int i = 0; i < vals.length - 2; i += 2) {
     doc.add(newField(vals[i], vals[i + 1], Field.Store.YES, Field.Index.ANALYZED));
   return doc;

class ElevationComparatorSource extends FieldComparatorSource {
  private final Map<String,Integer> priority;

  public ElevationComparatorSource(final Map<String,Integer> boosts) {
   this.priority = boosts;

  public FieldComparator newComparator(final String fieldname, final int numHits, int sortPos, boolean reversed) throws IOException {
   return new FieldComparator() {

     FieldCache.StringIndex idIndex;
     private final int[] values = new int[numHits];
     int bottomVal;

     public int compare(int slot1, int slot2) {
       return values[slot2] - values[slot1];  // values will be small enough that there is no overflow concern

     public void setBottom(int slot) {
       bottomVal = values[slot];

     private int docVal(int doc) throws IOException {
       String id = idIndex.lookup[idIndex.order[doc]];
       Integer prio = priority.get(id);
       return prio == null ? 0 : prio.intValue();

     public int compareBottom(int doc) throws IOException {
       return docVal(doc) - bottomVal;

     public void copy(int slot, int doc) throws IOException {
       values[slot] = docVal(doc);

     public void setNextReader(IndexReader reader, int docBase) throws IOException {
       idIndex = FieldCache.DEFAULT.getStringIndex(reader, fieldname);

     public Comparable<?> value(int slot) {
       return Integer.valueOf(values[slot]);

Other Lucene examples (source code examples)

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