Class CollectionUtils

java.lang.Object
org.codehaus.plexus.util.CollectionUtils

public class CollectionUtils extends Object
Author:
olamy
  • Constructor Details

    • CollectionUtils

      public CollectionUtils()
  • Method Details

    • mergeMaps

      public static <K, V> Map<K,V> mergeMaps(Map<K,V> dominantMap, Map<K,V> recessiveMap)
      Take a dominant and recessive Map and merge the key:value pairs where the recessive Map may add key:value pairs to the dominant Map but may not override any existing key:value pairs. If we have two Maps, a dominant and recessive, and their respective keys are as follows: dominantMapKeys = { a, b, c, d, e, f } recessiveMapKeys = { a, b, c, x, y, z } Then the result should be the following: resultantKeys = { a, b, c, d, e, f, x, y, z }
      Type Parameters:
      K - type
      V - type
      Parameters:
      dominantMap - Dominant Map.
      recessiveMap - Recessive Map.
      Returns:
      The result map with combined dominant and recessive values.
    • mergeMaps

      public static <K, V> Map<K,V> mergeMaps(Map<K,V>[] maps)
      Take a series of Maps and merge them where the ordering of the array from 0..n is the dominant order.
      Type Parameters:
      K - type
      V - type
      Parameters:
      maps - An array of Maps to merge.
      Returns:
      Map The result Map produced after the merging process.
    • intersection

      public static <E> Collection<E> intersection(Collection<E> a, Collection<E> b)

      Returns a Collection containing the intersection of the given Collections.

      The cardinality of each element in the returned Collection will be equal to the minimum of the cardinality of that element in the two given Collections.
      Type Parameters:
      E - the type
      Parameters:
      a - The first collection
      b - The second collection
      Returns:
      The intersection of a and b, never null
      See Also:
    • subtract

      public static <T> Collection<T> subtract(Collection<T> a, Collection<T> b)
      Returns a Collection containing a - b. The cardinality of each element e in the returned Collection will be the cardinality of e in a minus the cardinality of e in b, or zero, whichever is greater.
      Type Parameters:
      T - the type
      Parameters:
      a - The start collection
      b - The collection that will be subtracted
      Returns:
      The result of the subtraction
      See Also:
    • getCardinalityMap

      public static <E> Map<E,Integer> getCardinalityMap(Collection<E> col)
      Returns a Map mapping each unique element in the given Collection to an Integer representing the number of occurrences of that element in the Collection. An entry that maps to null indicates that the element does not appear in the given Collection.
      Type Parameters:
      E - the type
      Parameters:
      col - The collection to count cardinalities for
      Returns:
      A map of counts, indexed on each element in the collection
    • iteratorToList

      public static <E> List<E> iteratorToList(Iterator<E> it)