org.apache.lucene.search

Class FieldComparator.RelevanceComparator

java.lang.Object

org.apache.lucene.search.FieldComparator

org.apache.lucene.search.FieldComparator.RelevanceComparator

Enclosing class:

FieldComparator

public static final class FieldComparator.RelevanceComparator
extends FieldComparator

Sorts by descending relevance. NOTE: if you are sorting only by descending relevance and then secondarily by ascending docID, performance is faster using TopScoreDocCollector directly (which IndexSearcher.search(org.apache.lucene.search.Weight, org.apache.lucene.search.Filter, int) uses when no Sort is specified).

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.FieldComparator

FieldComparator.ByteComparator, FieldComparator.DocComparator, FieldComparator.DoubleComparator, FieldComparator.FloatComparator, FieldComparator.IntComparator, FieldComparator.LongComparator, FieldComparator.RelevanceComparator, FieldComparator.ShortComparator, FieldComparator.StringComparatorLocale, FieldComparator.StringOrdValComparator, FieldComparator.StringValComparator

Method Summary

Methods

Modifier and Type	Method and Description
int	compare(int slot1, int slot2) Compare hit at slot1 with hit at slot2.
int	compareBottom(int doc) Compare the bottom of the queue with doc.
void	copy(int slot, int doc) This method is called when a new hit is competitive.
void	setBottom(int bottom) Set the bottom slot, ie the "weakest" (sorted last) entry in the queue.
void	setNextReader(IndexReader reader, int docBase) Set a new Reader.
void	setScorer(Scorer scorer) Sets the Scorer to use in case a document's score is needed.
Comparable	value(int slot) Return the actual value in the slot.

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

binarySearch, binarySearch

Methods inherited from class java.lang.Object

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

Method Detail

compare

public int compare(int slot1,
          int slot2)

Description copied from class: FieldComparator

Compare hit at slot1 with hit at slot2.

Specified by:

compare in class FieldComparator

Parameters:

slot1 - first slot to compare

slot2 - second slot to compare

Returns:

any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

compareBottom

public int compareBottom(int doc)
                  throws IOException

Description copied from class: FieldComparator

Compare the bottom of the queue with doc. This will only invoked after setBottom has been called. This should return the same result as FieldComparator.compare(int,int)} as if bottom were slot1 and the new document were slot 2.

For a search that hits many results, this method will be the hotspot (invoked by far the most frequently).

Specified by:

compareBottom in class FieldComparator

Parameters:

doc - that was hit

Returns:

any N < 0 if the doc's value is sorted after the bottom entry (not competitive), any N > 0 if the doc's value is sorted before the bottom entry and 0 if they are equal.

Throws:

IOException

copy

public void copy(int slot,
        int doc)
          throws IOException

Description copied from class: FieldComparator

This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.

Specified by:

copy in class FieldComparator

Parameters:

slot - which slot to copy the hit to

doc - docID relative to current reader

Throws:

IOException

setNextReader

public void setNextReader(IndexReader reader,
                 int docBase)

Description copied from class: FieldComparator

Set a new Reader. All doc correspond to the current Reader.

Specified by:

setNextReader in class FieldComparator

Parameters:

reader - current reader

docBase - docBase of this reader

setBottom

public void setBottom(int bottom)

Description copied from class: FieldComparator

Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When FieldComparator.compareBottom(int) is called, you should compare against this slot. This will always be called before FieldComparator.compareBottom(int).

Specified by:

setBottom in class FieldComparator

Parameters:

bottom - the currently weakest (sorted last) slot in the queue

setScorer

public void setScorer(Scorer scorer)

Description copied from class: FieldComparator

Sets the Scorer to use in case a document's score is needed.

Overrides:

setScorer in class FieldComparator

Parameters:

scorer - Scorer instance that you should use to obtain the current hit's score, if necessary.

value

public Comparable value(int slot)

Description copied from class: FieldComparator

Return the actual value in the slot.

Specified by:

value in class FieldComparator

Parameters:

slot - the value

Returns:

value in this slot upgraded to Comparable