Package org.apache.lucene.search

# Class SortedSetSortField

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

public class SortedSetSortField extends SortField
SortField for `SortedSetDocValues`.

A SortedSetDocValues contains multiple values for a field, so sorting with this technique "selects" a value as the representative sort value for the document.

By default, the minimum value in the set is selected as the sort value, but this can be customized. Selectors other than the default do have some limitations to ensure that all selections happen in constant-time for performance.

Like sorting by string, this also supports sorting missing values as first or last, via `setMissingValue(Object)`.

See Also:
  - `SortedSetSelector`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static final class`
  `SortedSetSortField.Provider`
  A SortFieldProvider for this sort

  ## Nested classes/interfaces inherited from class org.apache.lucene.search.SortField

  `SortField.Type`

- ## Field Summary

  ### Fields inherited from class org.apache.lucene.search.SortField

  `FIELD_DOC, FIELD_SCORE, missingValue, STRING_FIRST, STRING_LAST`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `SortedSetSortField(String field, boolean reverse)`
  Creates a sort, possibly in reverse, by the minimum value in the set for the document.
  `SortedSetSortField(String field, boolean reverse, SortedSetSelector.Type selector)`
  Creates a sort, possibly in reverse, specifying how the sort value from the document's set is selected.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `equals(Object obj)`
  Returns true if `o` is equal to this.
  `FieldComparator<?>`
  `getComparator(int numHits, Pruning pruning)`
  Returns the `FieldComparator` to use for sorting.
  `IndexSorter`
  `getIndexSorter()`
  Returns an `IndexSorter` used for sorting index segments by this SortField.
  `SortedSetSelector.Type`
  `getSelector()`
  Returns the selector in use for this sort
  `int`
  `hashCode()`
  Returns a hash code for this `SortField` instance.
  `void`
  `setMissingValue(Object missingValue)`
  Set how missing values (the empty set) are sorted.
  `String`
  `toString()`

  ### Methods inherited from class org.apache.lucene.search.SortField

  `getBytesComparator, getComparatorSource, getField, getMissingValue, getOptimizeSortWithIndexedData, getOptimizeSortWithPoints, getReverse, getType, needsScores, readType, rewrite, setBytesComparator, setOptimizeSortWithIndexedData, setOptimizeSortWithPoints`

  ### Methods inherited from class java.lang.Object

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

- ## Constructor Details

  - ### SortedSetSortField

    public SortedSetSortField(String field, boolean reverse)
    Creates a sort, possibly in reverse, by the minimum value in the set for the document.
    Parameters:
      `field` - Name of field to sort by. Must not be null.
      `reverse` - True if natural order should be reversed.

  - ### SortedSetSortField

    public SortedSetSortField(String field, boolean reverse, SortedSetSelector.Type selector)
    Creates a sort, possibly in reverse, specifying how the sort value from the document's set is selected.
    Parameters:
      `field` - Name of field to sort by. Must not be null.
      `reverse` - True if natural order should be reversed.
      `selector` - custom selector type for choosing the sort value from the set.

      NOTE: selectors other than `SortedSetSelector.Type.MIN` require optional codec support.

- ## Method Details

  - ### getSelector

    public SortedSetSelector.Type getSelector()
    Returns the selector in use for this sort

  - ### hashCode

    public int hashCode()
    Description copied from class: `SortField`
    Returns a hash code for this `SortField` instance. If a `FieldComparatorSource` was provided, it must properly implement hashCode (unless a singleton is always used).
    Overrides:
      `hashCode` in class `SortField`

  - ### equals

    public boolean equals(Object obj)
    Description copied from class: `SortField`
    Returns true if `o` is equal to this. If a `FieldComparatorSource` was provided, it must properly implement equals (unless a singleton is always used).
    Overrides:
      `equals` in class `SortField`

  - ### toString

    public String toString()
    Overrides:
      `toString` in class `SortField`

  - ### setMissingValue

    public void setMissingValue(Object missingValue)
    Set how missing values (the empty set) are sorted.

    Note that this must be `SortField.STRING_FIRST` or `SortField.STRING_LAST`.

    Overrides:
      `setMissingValue` in class `SortField`

  - ### getComparator

    public FieldComparator<?> getComparator(int numHits, Pruning pruning)
    Description copied from class: `SortField`
    Returns the `FieldComparator` to use for sorting.
    Overrides:
      `getComparator` in class `SortField`
    Parameters:
      `numHits` - number of top hits the queue will store
      `pruning` - controls how can the comparator to skip documents via `LeafFieldComparator.competitiveIterator()`
    Returns:
      `FieldComparator` to use when sorting

  - ### getIndexSorter

    public IndexSorter getIndexSorter()
    Description copied from class: `SortField`
    Returns an `IndexSorter` used for sorting index segments by this SortField.

    If the SortField cannot be used for index sorting (for example, if it uses scores or other query-dependent values) then this method should return `null`

    SortFields that implement this method should also implement a companion `SortFieldProvider` to serialize and deserialize the sort in index segment headers

    Overrides:
      `getIndexSorter` in class `SortField`