Class CollectionUtils

getCardinalityMap

public static Map getCardinalityMap(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.

intersection

public static Collection intersection(Collection a,
                                      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

iteratorToList

public static List iteratorToList(Iterator it)

mergeMaps

public static Map mergeMaps(Map dominantMap,
                            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 Map mergeMaps(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.

subtract

public static Collection subtract(Collection a,
                                  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