Package org.apache.lucene.util

Class CollectionUtil

java.lang.Object

org.apache.lucene.util.CollectionUtil

public final class CollectionUtil
extends Object

Methods for manipulating (sorting) collections. Sort methods work directly on the supplied lists and don't copy to/from arrays before/after. For medium size collections as used in the Lucene indexer that is much more efficient.

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Method Summary

Modifier and Type	Method	Description
static <T extends Comparable<? super T>> void	introSort(List<T> list)	Sorts the given random access List in natural order.
static <T> void	introSort(List<T> list, Comparator<? super T> comp)	Sorts the given random access List using the Comparator.
static <T extends Comparable<? super T>> void	timSort(List<T> list)	Sorts the given random access List in natural order.
static <T> void	timSort(List<T> list, Comparator<? super T> comp)	Sorts the given random access List using the Comparator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

introSort

public static <T> void introSort(List<T> list,
 Comparator<? super T> comp)

Sorts the given random access List using the Comparator. The list must implement RandomAccess. This method uses the intro sort algorithm, but falls back to insertion sort for small lists.

Throws:

IllegalArgumentException - if list is e.g. a linked list without random access.

See Also:

• IntroSorter

introSort

public static <T extends Comparable<? super T>>
void introSort(List<T> list)

Sorts the given random access List in natural order. The list must implement RandomAccess. This method uses the intro sort algorithm, but falls back to insertion sort for small lists.

Throws:

IllegalArgumentException - if list is e.g. a linked list without random access.

See Also:

• IntroSorter

timSort

public static <T> void timSort(List<T> list,
 Comparator<? super T> comp)

Sorts the given random access List using the Comparator. The list must implement RandomAccess. This method uses the Tim sort algorithm, but falls back to binary sort for small lists.

Throws:

IllegalArgumentException - if list is e.g. a linked list without random access.

See Also:

• TimSorter

timSort

public static <T extends Comparable<? super T>>
void timSort(List<T> list)

Sorts the given random access List in natural order. The list must implement RandomAccess. This method uses the Tim sort algorithm, but falls back to binary sort for small lists.

Throws:

IllegalArgumentException - if list is e.g. a linked list without random access.

See Also:

• TimSorter