Package org.apache.lucene.search

Interface Collector

All Known Subinterfaces:

GenericTermsCollector

All Known Implementing Classes:

AllGroupHeadsCollector, AllGroupHeadsCollector.ScoringGroupHeadsCollector, AllGroupHeadsCollector.SortingGroupHeadsCollector, AllGroupsCollector, BlockGroupingCollector, CachingCollector, CachingCollector.NoScoreCachingCollector, CachingCollector.ScoreCachingCollector, CollectingMatcher.MatchCollector, DistinctValuesCollector, DistinctValuesCollector.ValuesCollector, DiversifiedTopDocsCollector, DocValuesStatsCollector, DocValuesTermsCollector, FilterCollector, FirstPassGroupingCollector, GlobalOrdinalsCollector, GlobalOrdinalsWithScoreCollector, GlobalOrdinalsWithScoreCollector.Avg, GlobalOrdinalsWithScoreCollector.Max, GlobalOrdinalsWithScoreCollector.Min, GlobalOrdinalsWithScoreCollector.NoScore, GlobalOrdinalsWithScoreCollector.Sum, GroupFacetCollector, LargeNumHitsTopDocsCollector, MemoryAccountingBitsetCollector, MultiCollector, MultiCollectorManager.Collectors, PositiveScoresOnlyCollector, QueryIndex.MonitorQueryCollector, SecondPassGroupingCollector, SimpleCollector, TermGroupFacetCollector, TermGroupFacetCollector.MV, TermGroupFacetCollector.SV, TermsCollector, TermsCollector.MV, TermsCollector.SV, TermsWithScoreCollector, TermsWithScoreCollector.MV, TermsWithScoreCollector.MV.Avg, TermsWithScoreCollector.SV, TermsWithScoreCollector.SV.Avg, TimeLimitingCollector, TopDocsCollector, TopFieldCollector, TopFieldCollector.PagingFieldCollector, TopFieldCollector.SimpleFieldCollector, TopGroupsCollector, TopGroupsCollector.MaxScoreCollector, TopGroupsCollector.TopDocsAndMaxScoreCollector, TopScoreDocCollector, TopScoreDocCollector.PagingTopScoreDocCollector, TopScoreDocCollector.SimpleTopScoreDocCollector, TopSuggestDocsCollector, TotalHitCountCollector

public interface Collector

Expert: Collectors are primarily meant to be used to gather raw results from a search, and implement sorting or custom result filtering, collation, etc.

Lucene's core collectors are derived from Collector and SimpleCollector. Likely your application can use one of these classes, or subclass TopDocsCollector, instead of implementing Collector directly:

• TopDocsCollector is an abstract base class that assumes you will retrieve the top N docs, according to some criteria, after collection is done.
• TopScoreDocCollector is a concrete subclass TopDocsCollector and sorts according to score + docID. This is used internally by the IndexSearcher search methods that do not take an explicit Sort. It is likely the most frequently used collector.
• TopFieldCollector subclasses TopDocsCollector and sorts according to a specified Sort object (sort by field). This is used internally by the IndexSearcher search methods that take an explicit Sort.
• TimeLimitingCollector, which wraps any other Collector and aborts the search if it's taken too much time.
• PositiveScoresOnlyCollector wraps any other Collector and prevents collection of hits whose score is <= 0.0

Method Summary

Modifier and Type	Method	Description
LeafCollector	getLeafCollector(LeafReaderContext context)	Create a new collector to collect the given context.
ScoreMode	scoreMode()	Indicates what features are required from the scorer.

Method Details

getLeafCollector

LeafCollector getLeafCollector(LeafReaderContext context)
                        throws IOException

Create a new collector to collect the given context.

Parameters:

context - next atomic reader context

Throws:

IOException

scoreMode

ScoreMode scoreMode()

Indicates what features are required from the scorer.