org.apache.lucene.search

Class TopScoreDocCollector

java.lang.Object

org.apache.lucene.search.TopDocsCollector<ScoreDoc>

org.apache.lucene.search.TopScoreDocCollector

All Implemented Interfaces:

Collector

public abstract class TopScoreDocCollector
extends TopDocsCollector<ScoreDoc>

A Collector implementation that collects the top-scoring hits, returning them as a TopDocs. This is used by IndexSearcher to implement TopDocs-based search. Hits are sorted by score descending and then (when the scores are tied) docID ascending. When you create an instance of this collector you should know in advance whether documents are going to be collected in doc Id order or not.

NOTE: The values Float.NaN and Float.NEGATIVE_INFINITY are not valid scores. This collector will not properly collect hits with such scores.

Field Summary

Fields inherited from class org.apache.lucene.search.TopDocsCollector

EMPTY_TOPDOCS, pq, totalHits

Method Summary

Modifier and Type	Method and Description
static TopScoreDocCollector	create(int numHits) Creates a new TopScoreDocCollector given the number of hits to collect and whether documents are scored in order by the input Scorer to LeafCollector.setScorer(Scorer).
static TopScoreDocCollector	create(int numHits, ScoreDoc after) Creates a new TopScoreDocCollector given the number of hits to collect, the bottom of the previous page, and whether documents are scored in order by the input Scorer to LeafCollector.setScorer(Scorer).
boolean	needsScores() Indicates if document scores are needed by this collector.
protected TopDocs	newTopDocs(ScoreDoc[] results, int start) Returns a TopDocs instance containing the given results.

Methods inherited from class org.apache.lucene.search.TopDocsCollector

getTotalHits, populateResults, topDocs, topDocs, topDocs, topDocsSize

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.lucene.search.Collector

getLeafCollector

Method Detail

create

public static TopScoreDocCollector create(int numHits)

Creates a new TopScoreDocCollector given the number of hits to collect and whether documents are scored in order by the input Scorer to LeafCollector.setScorer(Scorer).

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

create

public static TopScoreDocCollector create(int numHits,
                                          ScoreDoc after)

Creates a new TopScoreDocCollector given the number of hits to collect, the bottom of the previous page, and whether documents are scored in order by the input Scorer to LeafCollector.setScorer(Scorer).

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

newTopDocs

protected TopDocs newTopDocs(ScoreDoc[] results,
                             int start)

Description copied from class: TopDocsCollector

Returns a TopDocs instance containing the given results. If results is null it means there are no results to return, either because there were 0 calls to collect() or because the arguments to topDocs were invalid.

Overrides:

newTopDocs in class TopDocsCollector<ScoreDoc>

needsScores

public boolean needsScores()

Description copied from interface: Collector

Indicates if document scores are needed by this collector.

Returns:

true if scores are needed.