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Lucene example source code file (TestScoreCachingWrappingScorer.java)

This example Lucene source code file (TestScoreCachingWrappingScorer.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

exception, io, ioexception, ioexception, lucenetestcase, no_more_docs, override, override, scorecachingcollector, scorecachingwrappingscorer, scorer, scorer, simplescorer, simplescorer, testscorecachingwrappingscorer

The Lucene TestScoreCachingWrappingScorer.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 java.io.IOException;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.util.LuceneTestCase;

public class TestScoreCachingWrappingScorer extends LuceneTestCase {

  private static final class SimpleScorer extends Scorer {
    private int idx = 0;
    private int doc = -1;
    public SimpleScorer() {
    @Override public float score() throws IOException {
      // advance idx on purpose, so that consecutive calls to score will get
      // different results. This is to emulate computation of a score. If
      // ScoreCachingWrappingScorer is used, this should not be called more than
      // once per document.
      return idx == scores.length ? Float.NaN : scores[idx++];

    @Override public int docID() { return doc; }

    @Override public int nextDoc() throws IOException {
      return ++doc < scores.length ? doc : NO_MORE_DOCS;
    @Override public int advance(int target) throws IOException {
      doc = target;
      return doc < scores.length ? doc : NO_MORE_DOCS;
  private static final class ScoreCachingCollector extends Collector {

    private int idx = 0;
    private Scorer scorer;
    float[] mscores;
    public ScoreCachingCollector(int numToCollect) {
      mscores = new float[numToCollect];
    @Override public void collect(int doc) throws IOException {
      // just a sanity check to avoid IOOB.
      if (idx == mscores.length) {
      // just call score() a couple of times and record the score.
      mscores[idx] = scorer.score();
      mscores[idx] = scorer.score();
      mscores[idx] = scorer.score();

    @Override public void setNextReader(IndexReader reader, int docBase)
        throws IOException {

    @Override public void setScorer(Scorer scorer) throws IOException {
      this.scorer = new ScoreCachingWrappingScorer(scorer);
    @Override public boolean acceptsDocsOutOfOrder() {
      return true;


  private static final float[] scores = new float[] { 0.7767749f, 1.7839992f,
      8.9925785f, 7.9608946f, 0.07948637f, 2.6356435f, 7.4950366f, 7.1490803f,
      8.108544f, 4.961808f, 2.2423935f, 7.285586f, 4.6699767f };
  public void testGetScores() throws Exception {
    Scorer s = new SimpleScorer();
    ScoreCachingCollector scc = new ScoreCachingCollector(scores.length);
    // We need to iterate on the scorer so that its doc() advances.
    int doc;
    while ((doc = s.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
    for (int i = 0; i < scores.length; i++) {
      assertEquals(scores[i], scc.mscores[i], 0f);

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