Package org.apache.lucene.search

Class SortField

java.lang.Object
org.apache.lucene.search.SortField
public class SortField extends Object
Stores information about how to sort documents by terms in an individual field. Fields must be indexed in order to sort by them.

Created: Feb 11, 2004 1:25:29 PM

Since:
lucene 1.4
See Also:

  • Field Details

    • FIELD_SCORE

      public static final SortField FIELD_SCORE
      Represents sorting by document score (relevance).

    • FIELD_DOC

      public static final SortField FIELD_DOC
      Represents sorting by document number (index order).

    • missingValue

      public Object missingValue

    • sortMissingLast

      public boolean sortMissingLast

    • STRING_FIRST

      public static final Object STRING_FIRST
      Pass this to setMissingValue(java.lang.Object) to have missing string values sort first.

    • STRING_LAST

      public static final Object STRING_LAST
      Pass this to setMissingValue(java.lang.Object) to have missing string values sort last.

  • Constructor Details

    • SortField

      public SortField(String field, SortField.Type type)
      Creates a sort by terms in the given field with the type of term values explicitly given.
      Parameters:
      field - Name of field to sort by. Can be null if type is SCORE or DOC.
      type - Type of values in the terms.

    • SortField

      public SortField(String field, SortField.Type type, boolean reverse)
      Creates a sort, possibly in reverse, by terms in the given field with the type of term values explicitly given.
      Parameters:
      field - Name of field to sort by. Can be null if type is SCORE or DOC.
      type - Type of values in the terms.
      reverse - True if natural order should be reversed.

    • SortField

      public SortField(String field, FieldCache.Parser parser)
      Creates a sort by terms in the given field, parsed to numeric values using a custom FieldCache.Parser.
      Parameters:
      field - Name of field to sort by. Must not be null.
      parser - Instance of a FieldCache.Parser, which must subclass one of the existing numeric parsers from FieldCache. Sort type is inferred by testing which numeric parser the parser subclasses.
      Throws:
      IllegalArgumentException - if the parser fails to subclass an existing numeric parser, or field is null

    • SortField

      public SortField(String field, FieldCache.Parser parser, boolean reverse)
      Creates a sort, possibly in reverse, by terms in the given field, parsed to numeric values using a custom FieldCache.Parser.
      Parameters:
      field - Name of field to sort by. Must not be null.
      parser - Instance of a FieldCache.Parser, which must subclass one of the existing numeric parsers from FieldCache. Sort type is inferred by testing which numeric parser the parser subclasses.
      reverse - True if natural order should be reversed.
      Throws:
      IllegalArgumentException - if the parser fails to subclass an existing numeric parser, or field is null

    • SortField

      public SortField(String field, FieldComparatorSource comparator)
      Creates a sort with a custom comparison function.
      Parameters:
      field - Name of field to sort by; cannot be null.
      comparator - Returns a comparator for sorting hits.

    • SortField

      public SortField(String field, FieldComparatorSource comparator, boolean reverse)
      Creates a sort, possibly in reverse, with a custom comparison function.
      Parameters:
      field - Name of field to sort by; cannot be null.
      comparator - Returns a comparator for sorting hits.
      reverse - True if natural order should be reversed.

  • Method Details

    • setMissingValue

      public void setMissingValue(Object missingValue)

    • getField

      public String getField()
      Returns the name of the field. Could return null if the sort is by SCORE or DOC.
      Returns:
      Name of field, possibly null.

    • getType

      public SortField.Type getType()
      Returns the type of contents in the field.
      Returns:
      One of the constants SCORE, DOC, STRING, INT or FLOAT.

    • getParser

      public FieldCache.Parser getParser()
      Returns the instance of a FieldCache parser that fits to the given sort type. May return null if no parser was specified. Sorting is using the default parser then.
      Returns:
      An instance of a FieldCache parser, or null.

    • getReverse

      public boolean getReverse()
      Returns whether the sort should be reversed.
      Returns:
      True if natural order should be reversed.

    • getComparatorSource

      public FieldComparatorSource getComparatorSource()
      Returns the FieldComparatorSource used for custom sorting

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • equals

      public boolean equals(Object o)
      Returns true if o is equal to this. If a FieldComparatorSource or FieldCache.Parser was provided, it must properly implement equals (unless a singleton is always used).
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Returns true if o is equal to this. If a FieldComparatorSource or FieldCache.Parser was provided, it must properly implement hashCode (unless a singleton is always used).
      Overrides:
      hashCode in class Object

    • setBytesComparator

      public void setBytesComparator(Comparator<BytesRef> b)

    • getBytesComparator

      public Comparator<BytesRef> getBytesComparator()

    • getComparator

      public FieldComparator<?> getComparator(int numHits, int sortPos) throws IOException
      Returns the FieldComparator to use for sorting.
      Parameters:
      numHits - number of top hits the queue will store
      sortPos - position of this SortField within Sort. The comparator is primary if sortPos==0, secondary if sortPos==1, etc. Some comparators can optimize themselves when they are the primary sort.
      Returns:
      FieldComparator to use when sorting
      Throws:
      IOException

    • rewrite

      public SortField rewrite(IndexSearcher searcher) throws IOException
      Rewrites this SortField, returning a new SortField if a change is made. Subclasses should override this define their rewriting behavior when this SortField is of type SortField.Type.REWRITEABLE
      Parameters:
      searcher - IndexSearcher to use during rewriting
      Returns:
      New rewritten SortField, or this if nothing has changed.
      Throws:
      IOException - Can be thrown by the rewriting

    • needsScores

      public boolean needsScores()
      Whether the relevance score is needed to sort documents.