org.apache.lucene.util

Class 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.
    • Method Detail

      • 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.
      • 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.
      • 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.
      • 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.