org.apache.lucene.search
Class FieldComparator.StringValComparator

java.lang.Object
  org.apache.lucene.search.FieldComparator<String>
      org.apache.lucene.search.FieldComparator.StringValComparator

Enclosing class:

FieldComparator<T>

public static final class FieldComparator.StringValComparator
extends FieldComparator<String>

Sorts by field's natural String sort order. All comparisons are done using String.compareTo, which is slow for medium to large result sets but possibly very fast for very small results sets.

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.NumericComparator<T extends Number>, 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.
int	compareValues(String val1, String val2) Returns -1 if first is less than second.
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.
String	value(int slot) Return the actual value in the slot.

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

binarySearch, binarySearch, setScorer

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<String>

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)

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<String>

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.

copy

public void copy(int slot,
                 int doc)

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<String>

Parameters:

slot - which slot to copy the hit to

doc - docID relative to current reader

setNextReader

public void setNextReader(IndexReader reader,
                          int docBase)
                   throws IOException

Description copied from class: FieldComparator

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

Specified by:

setNextReader in class FieldComparator<String>

Parameters:

reader - current reader

docBase - docBase of this reader

Throws:

IOException

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<String>

Parameters:

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

value

public String value(int slot)

Description copied from class: FieldComparator

Return the actual value in the slot.

Specified by:

value in class FieldComparator<String>

Parameters:

slot - the value

Returns:

value in this slot

compareValues

public int compareValues(String val1,
                         String val2)

Description copied from class: FieldComparator

Returns -1 if first is less than second. Default impl to assume the type implements Comparable and invoke .compareTo; be sure to override this method if your FieldComparator's type isn't a Comparable or if your values may sometimes be null

Overrides:

compareValues in class FieldComparator<String>