org.apache.lucene.search
Class FieldComparator.RelevanceComparator

java.lang.Object
  extended by org.apache.lucene.search.FieldComparator
      extended by 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
 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


Copyright © 2000-2010 Apache Software Foundation. All Rights Reserved.