Package org.apache.lucene.util

Class CollectionUtil

  • public final class CollectionUtil
extends java.lang.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 Summary

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

      • Methods inherited from class java.lang.Object

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

    • Method Detail

      • introSort

        public static <T> void introSort​(java.util.List<T> list,
                                 java.util.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:
        java.lang.IllegalArgumentException - if list is e.g. a linked list without random access.

      • introSort

        public static <T extends java.lang.Comparable<? super T>> void introSort​(java.util.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:
        java.lang.IllegalArgumentException - if list is e.g. a linked list without random access.

      • timSort

        public static <T> void timSort​(java.util.List<T> list,
                               java.util.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:
        java.lang.IllegalArgumentException - if list is e.g. a linked list without random access.

      • timSort

        public static <T extends java.lang.Comparable<? super T>> void timSort​(java.util.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:
        java.lang.IllegalArgumentException - if list is e.g. a linked list without random access.