org.apache.lucene.search
Class SortField

java.lang.Object
  org.apache.lucene.search.SortField

All Implemented Interfaces:

Serializable

public class SortField
extends Object
implements Serializable

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:

Sort, Serialized Form

Field Summary

static int	BYTE Sort using term values as encoded Bytes.
static int	CUSTOM Sort using a custom Comparator.
static int	DOC Sort by document number (index order).
static int	DOUBLE Sort using term values as encoded Doubles.
static SortField	FIELD_DOC Represents sorting by document number (index order).
static SortField	FIELD_SCORE Represents sorting by document score (relevance).
static int	FLOAT Sort using term values as encoded Floats.
static int	INT Sort using term values as encoded Integers.
static int	LONG Sort using term values as encoded Longs.
static int	SCORE Sort by document score (relevance).
static int	SHORT Sort using term values as encoded Shorts.
static int	STRING Sort using term values as Strings.
static int	STRING_VAL Sort using term values as Strings, but comparing by value (using String.compareTo) for all comparisons.

Constructor Summary

SortField(String field, FieldCache.Parser parser)
Creates a sort by terms in the given field, parsed to numeric values using a custom FieldCache.Parser.

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.

SortField(String field, FieldComparatorSource comparator)
Creates a sort with a custom comparison function.

SortField(String field, FieldComparatorSource comparator, boolean reverse)
Creates a sort, possibly in reverse, with a custom comparison function.

SortField(String field, int type)
Creates a sort by terms in the given field with the type of term values explicitly given.

SortField(String field, int type, boolean reverse)
Creates a sort, possibly in reverse, by terms in the given field with the type of term values explicitly given.

SortField(String field, Locale locale)
Creates a sort by terms in the given field sorted according to the given locale.

SortField(String field, Locale locale, boolean reverse)
Creates a sort, possibly in reverse, by terms in the given field sorted according to the given locale.

Method Summary

boolean	equals(Object o) Returns true if o is equal to this.
FieldComparator<?>	getComparator(int numHits, int sortPos) Returns the FieldComparator to use for sorting.
FieldComparatorSource	getComparatorSource() Returns the FieldComparatorSource used for custom sorting
String	getField() Returns the name of the field.
Locale	getLocale() Returns the Locale by which term values are interpreted.
FieldCache.Parser	getParser() Returns the instance of a FieldCache parser that fits to the given sort type.
boolean	getReverse() Returns whether the sort should be reversed.
int	getType() Returns the type of contents in the field.
int	hashCode() Returns true if o is equal to this.
SortField	setMissingValue(Object missingValue) Set a default sorting value for documents which lacks one
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

SCORE

public static final int SCORE

Sort by document score (relevance). Sort values are Float and higher values are at the front.

See Also:

Constant Field Values

DOC

public static final int DOC

Sort by document number (index order). Sort values are Integer and lower values are at the front.

See Also:

Constant Field Values

STRING

public static final int STRING

Sort using term values as Strings. Sort values are String and lower values are at the front.

See Also:

Constant Field Values

INT

public static final int INT

Sort using term values as encoded Integers. Sort values are Integer and lower values are at the front.

See Also:

Constant Field Values

FLOAT

public static final int FLOAT

Sort using term values as encoded Floats. Sort values are Float and lower values are at the front.

See Also:

Constant Field Values

LONG

public static final int LONG

Sort using term values as encoded Longs. Sort values are Long and lower values are at the front.

See Also:

Constant Field Values

DOUBLE

public static final int DOUBLE

Sort using term values as encoded Doubles. Sort values are Double and lower values are at the front.

See Also:

Constant Field Values

SHORT

public static final int SHORT

Sort using term values as encoded Shorts. Sort values are Short and lower values are at the front.

See Also:

Constant Field Values

CUSTOM

public static final int CUSTOM

Sort using a custom Comparator. Sort values are any Comparable and sorting is done according to natural order.

See Also:

Constant Field Values

BYTE

public static final int BYTE

Sort using term values as encoded Bytes. Sort values are Byte and lower values are at the front.

See Also:

Constant Field Values

STRING_VAL

public static final int STRING_VAL

Sort using term values as Strings, but comparing by value (using String.compareTo) for all comparisons. This is typically slower than STRING, which uses ordinals to do the sorting.

See Also:

Constant Field Values

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).

Constructor Detail

SortField

public SortField(String field,
                 int 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,
                 int 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,
                 Locale locale)

Creates a sort by terms in the given field sorted according to the given locale.

Parameters:

field - Name of field to sort by, cannot be null.

locale - Locale of values in the field.

SortField

public SortField(String field,
                 Locale locale,
                 boolean reverse)

Creates a sort, possibly in reverse, by terms in the given field sorted according to the given locale.

Parameters:

field - Name of field to sort by, cannot be null.

locale - Locale of values in the field.

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 Detail

setMissingValue

public SortField setMissingValue(Object missingValue)

Set a default sorting value for documents which lacks one

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 int getType()

Returns the type of contents in the field.

Returns:

One of the constants SCORE, DOC, STRING, INT or FLOAT.

getLocale

public Locale getLocale()

Returns the Locale by which term values are interpreted. May return null if no Locale was specified.

Returns:

Locale, or null.

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

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

WARNING: This API is experimental and might change in incompatible ways in the next release.