org.codehaus.plexus.util
Class CollectionUtils

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

public class CollectionUtils
extends java.lang.Object

Version:

$Id: CollectionUtils.java 8055 2009-01-16 12:45:08Z vsiveton $

Author:

olamy

Constructor Summary

CollectionUtils()

Method Summary

static java.util.Map	getCardinalityMap(java.util.Collection col) Returns a Map mapping each unique element in the given Collection to an Integer representing the number of occurances of that element in the Collection.
static java.util.Collection	intersection(java.util.Collection a, java.util.Collection b) Returns a Collection containing the intersection of the given Collections.
static java.util.List	iteratorToList(java.util.Iterator it)
static java.util.Map	mergeMaps(java.util.Map[] maps) Take a series of Maps and merge them where the ordering of the array from 0..n is the dominant order.
static java.util.Map	mergeMaps(java.util.Map dominantMap, java.util.Map 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.
static java.util.Collection	subtract(java.util.Collection a, java.util.Collection b) Returns a Collection containing a - b.

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionUtils

public CollectionUtils()

Method Detail

mergeMaps

public static java.util.Map mergeMaps(java.util.Map dominantMap,
                                      java.util.Map 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 }

Parameters:

dominantMap - Dominant Map.

recessiveMap - Recessive Map.

Returns:

The result map with combined dominant and recessive values.

mergeMaps

public static java.util.Map mergeMaps(java.util.Map[] maps)

Take a series of Maps and merge them where the ordering of the array from 0..n is the dominant order.

Parameters:

maps - An array of Maps to merge.

Returns:

Map The result Map produced after the merging process.

intersection

public static java.util.Collection intersection(java.util.Collection a,
                                                java.util.Collection 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.

See Also:

Collection.retainAll(java.util.Collection)

subtract

public static java.util.Collection subtract(java.util.Collection a,
                                            java.util.Collection 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.

See Also:

Collection.removeAll(java.util.Collection)

getCardinalityMap

public static java.util.Map getCardinalityMap(java.util.Collection col)

Returns a Map mapping each unique element in the given Collection to an Integer representing the number of occurances of that element in the Collection. An entry that maps to null indicates that the element does not appear in the given Collection.

iteratorToList

public static java.util.List iteratorToList(java.util.Iterator it)