Package org.opensearch.core.common.util

Class CollectionUtils

java.lang.Object
org.opensearch.core.common.util.CollectionUtils
public class CollectionUtils extends Object
Collections-related utility methods.
Opensearch.internal:

  • Constructor Details

    • CollectionUtils

      public CollectionUtils()

  • Method Details

    • isEmpty

      public static boolean isEmpty(Object[] array)
      Checks if the given array contains any elements.
      Parameters:
      array - The array to check
      Returns:
      false if the array contains an element, true if not or the array is null.

    • rotate

      public static <T> List<T> rotate(List<T> list, int distance)
      Return a rotated view of the given list with the given distance.
      • The distance can be negative, in which case the list is rotated to the left.
      • The distance can be larger than the size of the list, in which case the list is rotated multiple times.
      • The distance can be zero, in which case the list is not rotated.
      • The list can be empty, in which case it remains empty.
      Parameters:
      list - the list to rotate
      distance - the distance to rotate (positive rotates right, negative rotates left)
      Returns:
      a rotated view of the given list with the given distance
      See Also:
      • CollectionUtils.RotatedList

    • sortAndDedup

      public static <T> void sortAndDedup(List<T> array, Comparator<T> comparator)
      In place de-duplicates items in a list Noop if the list is empty or has one item.
      Type Parameters:
      T - the type of the items in the list
      Parameters:
      array - the list to de-duplicate
      comparator - the comparator to use to compare items
      Throws:
      NullPointerException - if the list is `null` or comparator is `null`

    • toArray

      public static int[] toArray(Collection<Integer> ints)
      Converts a collection of Integers to an array of ints.
      Parameters:
      ints - The collection of Integers to convert
      Returns:
      The array of ints
      Throws:
      NullPointerException - if ints is null

    • ensureNoSelfReferences

      public static void ensureNoSelfReferences(Object value, String messageHint)
      Deeply inspects a Map, Iterable, or Object array looking for references back to itself.
      Parameters:
      value - The object to evaluate looking for self references
      messageHint - A string to be included in the exception message if the call fails, to provide more context to the handler of the exception
      Throws:
      IllegalArgumentException - if a self-reference is found

    • copyMap

      public static <R, T> Map<R,T> copyMap(Map<R,T> map)
      Returns an unmodifiable copy of the given map.
      Parameters:
      map - Map to copy
      Returns:
      unmodifiable copy of the map

    • iterableAsArrayList

      public static <E> ArrayList<E> iterableAsArrayList(Iterable<? extends E> elements)
      Converts an Iterable to an ArrayList.
      Type Parameters:
      E - the type the elements
      Parameters:
      elements - The iterable to convert
      Returns:
      an ArrayList
      Throws:
      NullPointerException - if elements is null

    • arrayAsArrayList

      public static <E> ArrayList<E> arrayAsArrayList(E... elements)

    • asArrayList

      public static <E> ArrayList<E> asArrayList(E first, E... other)

    • asArrayList

      public static <E> ArrayList<E> asArrayList(E first, E second, E... other)

    • newSingletonArrayList

      public static <E> ArrayList<E> newSingletonArrayList(E element)

    • eagerPartition

      public static <E> List<List<E>> eagerPartition(List<E> list, int size)

    • isEmpty

      public static <E> boolean isEmpty(Collection<E> collection)
      Checks if a collection is empty or not. Empty collection mean either it is null or it has no elements in it. If collection contains a null element it means it is not empty.
      Type Parameters:
      E - Element
      Parameters:
      collection - Collection
      Returns:
      true if collection is null or isEmpty(), false otherwise