org.apache.lucene.search

Class TopFieldDocCollector

java.lang.Object

org.apache.lucene.search.HitCollector

org.apache.lucene.search.TopDocCollector

org.apache.lucene.search.TopFieldDocCollector

public class TopFieldDocCollector
extends TopDocCollector

A HitCollector implementation that collects the top-sorting documents, returning them as a TopFieldDocs. This is used by IndexSearcher to implement TopFieldDocs-based search.

This may be extended, overriding the collect method to, e.g., conditionally invoke super() in order to filter which documents are collected.

Constructor Summary

Constructors

Constructor and Description
TopFieldDocCollector(IndexReader reader, Sort sort, int numHits) Construct to collect a given number of hits.

Method Summary

Modifier and Type	Method and Description
void	collect(int doc, float score) Called once for every document matching a query, with the document number and its raw score.
TopDocs	topDocs() The top-scoring hits.

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

getTotalHits

Methods inherited from class java.lang.Object

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

Constructor Detail

TopFieldDocCollector

public TopFieldDocCollector(IndexReader reader,
                            Sort sort,
                            int numHits)
                     throws java.io.IOException

Construct to collect a given number of hits.

Parameters:

reader - the index to be searched

sort - the sort criteria

numHits - the maximum number of hits to collect

Throws:

java.io.IOException

Method Detail

collect

public void collect(int doc,
                    float score)

Description copied from class: HitCollector

Called once for every document matching a query, with the document number and its raw score.

If, for example, an application wished to collect all of the hits for a query in a BitSet, then it might:

   Searcher searcher = new IndexSearcher(indexReader);
   final BitSet bits = new BitSet(indexReader.maxDoc());
   searcher.search(query, new HitCollector() {
       public void collect(int doc, float score) {
         bits.set(doc);
       }
     });
 

Note: This is called in an inner search loop. For good search performance, implementations of this method should not call Searcher.doc(int) or IndexReader.document(int) on every document number encountered. Doing so can slow searches by an order of magnitude or more.

Note: The score passed to this method is a raw score. In other words, the score will not necessarily be a float whose value is between 0 and 1.

Overrides:

collect in class TopDocCollector

topDocs

public TopDocs topDocs()

Description copied from class: TopDocCollector

The top-scoring hits.

Overrides:

topDocs in class TopDocCollector