Package org.apache.lucene.util
Class CollectionUtil
- java.lang.Object
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- org.apache.lucene.util.CollectionUtil
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public final class CollectionUtil extends Object
Methods for manipulating (sorting) and creating 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.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static <T extends Comparable<? super T>>
voidintroSort(List<T> list)
Sorts the given random accessList
in natural order.static <T> void
introSort(List<T> list, Comparator<? super T> comp)
Sorts the given random accessList
using theComparator
.static <K,V>
HashMap<K,V>newHashMap(int size)
Returns a newHashMap
sized to containsize
items without resizing the internal array.static <E> HashSet<E>
newHashSet(int size)
Returns a newHashSet
sized to containsize
items without resizing the internal array.static <T extends Comparable<? super T>>
voidtimSort(List<T> list)
Sorts the given random accessList
in natural order.static <T> void
timSort(List<T> list, Comparator<? super T> comp)
Sorts the given random accessList
using theComparator
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Method Detail
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newHashMap
public static <K,V> HashMap<K,V> newHashMap(int size)
Returns a newHashMap
sized to containsize
items without resizing the internal array.
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newHashSet
public static <E> HashSet<E> newHashSet(int size)
Returns a newHashSet
sized to containsize
items without resizing the internal array.
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introSort
public static <T> void introSort(List<T> list, Comparator<? super T> comp)
Sorts the given random accessList
using theComparator
. The list must implementRandomAccess
. 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
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introSort
public static <T extends Comparable<? super T>> void introSort(List<T> list)
Sorts the given random accessList
in natural order. The list must implementRandomAccess
. 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
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timSort
public static <T> void timSort(List<T> list, Comparator<? super T> comp)
Sorts the given random accessList
using theComparator
. The list must implementRandomAccess
. 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
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timSort
public static <T extends Comparable<? super T>> void timSort(List<T> list)
Sorts the given random accessList
in natural order. The list must implementRandomAccess
. 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
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