SortField (Lucene 4.10.0 API)

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

Direct Known Subclasses:

SortedNumericSortField
```
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:
Sort

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class SortField.Type
Specifies the type of the terms to be sorted, or special types such as CUSTOM

Nested Classes
Modifier and Type	Class and Description
`static class`	`SortField.Type` Specifies the type of the terms to be sorted, or special types such as CUSTOM

Field Summary

Fields
Modifier and Type	Field and Description
`static SortField`	`FIELD_DOC` Represents sorting by document number (index order).
`static SortField`	`FIELD_SCORE` Represents sorting by document score (relevance).
`Object`	`missingValue`
`static Object`	`STRING_FIRST` Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort first.
`static Object`	`STRING_LAST` Pass this to `setMissingValue(java.lang.Object)` to have missing string values sort last.

Constructor Summary

Constructors
Constructor and Description
`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, SortField.Type type)` Creates a sort by terms in the given field with the type of term values explicitly given.
`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.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object o)` Returns true if `o` is equal to this.
`Comparator<BytesRef>`	`getBytesComparator()`
`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.
`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.
`SortField.Type`	`getType()` Returns the type of contents in the field.
`int`	`hashCode()` Returns true if `o` is equal to this.
`boolean`	`needsScores()` Whether the relevance score is needed to sort documents.
`SortField`	`rewrite(IndexSearcher searcher)` Rewrites this SortField, returning a new SortField if a change is made.
`void`	`setBytesComparator(Comparator<BytesRef> b)`
`void`	`setMissingValue(Object missingValue)`
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - 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
```
  - 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 Detail
  - 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 Detail
  - 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
    WARNING: This API is experimental and might change in incompatible ways in the next release.
  - 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
    WARNING: This API is experimental and might change in incompatible ways in the next release.
  - needsScores
```
public boolean needsScores()
```
    Whether the relevance score is needed to sort documents.

Class SortField

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

FIELD_SCORE

FIELD_DOC

missingValue

STRING_FIRST

STRING_LAST

Constructor Detail

SortField

SortField

SortField

SortField

SortField

SortField

Method Detail

setMissingValue

getField

getType

getParser

getReverse

getComparatorSource

toString

equals

hashCode

setBytesComparator

getBytesComparator

getComparator

rewrite

needsScores