ERXArrayUtilities Class Reference

Collaboration diagram for ERXArrayUtilities:

[legend]

List of all members.

Classes
class	AvgNonNullOperator
class	BaseOperator
class	FetchSpecOperator
class	FlattenOperator
class	IsEmptyOperator
class	LimitOperator
class	MedianOperator
class	ObjectAtIndexOperator
class	RemoveNullValuesOperator
class	ReverseOperator
class	SortOperator
class	StandardDeviationOperator
class	SubarrayWithRangeOperator
class	UniqueOperator
Static Public Member Functions
static< T > void	addObjectsFromArrayWithoutDuplicates (NSMutableArray< T > a1, NSArray<?extends T > a2)
static< T > NSArray< T >	arrayByAddingObjectsFromArrayWithoutDuplicates (NSArray<?extends T > a1, NSArray<?extends T > a2)
static< T > NSArray< T >	arrayByRemovingFirstObject (NSArray< T > array)
static< T > NSArray< T >	arrayBySelectingInstancesOfClass (final NSArray<?> array, final Class< T > aClass)
static< T > boolean	arrayContainsAnyObjectFromArray (NSArray<?extends T > array, NSArray<?extends T > objects)
static< T > boolean	arrayContainsArray (NSArray<?extends T > array, NSArray<?extends T > objects)
static NSArray<?>	arrayForKeysPath (NSArray<?> array, NSArray< String > keys)
static NSArray	arrayFromPropertyList (String name, NSBundle bundle)
static NSDictionary	arrayGroupedByKeyPath (NSArray objects, String keyPath, Object nullGroupingKey, String valueKeyPath)
static< T, K, V > NSDictionary < K, NSArray< V > >	arrayGroupedByKeyPath (NSArray< T > objects, ERXKey< K > keyPath, K nullGroupingKey, ERXKey< V > valueKeyPath)
static< T, K, V > NSDictionary < K, NSArray< V > >	arrayGroupedByKeyPath (NSArray< T > objects, String keyPath, boolean includeNulls, String valueKeyPath)
static< T, K, V > NSDictionary < K, NSArray< V > >	arrayGroupedByKeyPath (NSArray< T > objects, ERXKey< K > keyPath, boolean includeNulls, ERXKey< V > valueKeyPath)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByKeyPath (NSArray< V > objects, String keyPath)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByKeyPath (NSArray< V > objects, ERXKey< K > keyPath)
static NSDictionary	arrayGroupedByToManyKeyPath (NSArray objects, String keyPath, Object nullGroupingKey, String valueKeyPath)
static< T, K, V > NSDictionary < K, NSArray< V > >	arrayGroupedByToManyKeyPath (NSArray< T > objects, ERXKey< K > keyPath, K nullGroupingKey, ERXKey< V > valueKeyPath)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByToManyKeyPath (NSArray< V > objects, String keyPath, K nullGroupingKey)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByToManyKeyPath (NSArray< V > objects, ERXKey< K > keyPath, K nullGroupingKey)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByToManyKeyPath (NSArray< V > objects, String keyPath, boolean includeNulls)
static< K, V > NSDictionary< K, NSArray< V > >	arrayGroupedByToManyKeyPath (NSArray< V > objects, ERXKey< K > keyPath, boolean includeNulls)
static< T > NSArray< T >	arrayMinusArray (NSArray< T > main, NSArray<?> minus)
static< T > NSArray< T >	arrayMinusObject (NSArray< T > main, Object object)
static< T > boolean	arraysAreIdenticalSets (NSArray<?super T > a1, NSArray<?super T > a2)
static< T > NSArray< T >	arrayWithObjectsAtIndexesSwapped (final NSArray< T > array, final int indexOfObject1, final int indexOfObject2)
static< T > NSArray< T >	arrayWithObjectsSwapped (final NSArray< T > array, final Object object1, final Object object2)
static< T > NSArray< T >	arrayWithoutDuplicateKeyValue (NSArray< T > objects, String key)
static< T > NSArray< T >	arrayWithoutDuplicates (NSArray< T > anArray)
static< T > NSArray< NSArray< T > >	batchedArrayWithSize (NSArray< T > array, int batchSize)
static< T > NSSet< T >	deepClone (NSSet< T > set, boolean onlyCollections)
static< T > NSArray< T >	deepClone (NSArray< T > array, boolean onlyCollections)
static< K, T > NSDictionary< K, T >	dictionaryOfObjectsIndexedByKeyPath (final NSArray< T > array, final String keyPath)
static< K, T > NSDictionary< K, T >	dictionaryOfObjectsIndexedByKeyPathThrowOnCollision (final NSArray< T > array, final String keyPath, final boolean throwOnCollision)
static< T > NSArray< T >	distinct (NSArray< T > array)
static boolean	enumerationHasMatchWithQualifierEvaluation (Enumeration<?> enumeration, EOQualifierEvaluation qualifier)
static< T > NSArray< T >	filteredArrayWithEntityFetchSpecification (NSArray< T > array, String entity, String fetchSpec)
static< T > NSArray< T >	filteredArrayWithEntityFetchSpecification (NSArray< T > array, String entity, String fetchSpec, NSDictionary< String,?> bindings)
static< T > NSArray< T >	filteredArrayWithFetchSpecificationNamedEntityNamed (NSArray< T > array, String fetchSpec, String entity)
static< T > NSArray< T >	filteredArrayWithFetchSpecificationNamedEntityNamedBindings (NSArray< T > array, String fetchSpec, String entity, NSDictionary< String,?> bindings)
static< T > NSArray< T >	filteredArrayWithQualifierEvaluation (Iterator< T > iterator, EOQualifierEvaluation qualifier)
static< T > NSArray< T >	filteredArrayWithQualifierEvaluation (Enumeration< T > enumeration, EOQualifierEvaluation qualifier)
static< T > NSArray< T >	filteredArrayWithQualifierEvaluation (NSArray< T > array, EOQualifierEvaluation qualifier)
static< T > T	firstObject (NSArray< T > array)
static< T > T	firstObjectWithValueForKeyPath (NSArray< T > array, Object value, String keyPath)
static NSArray	flatten (NSArray<?> originalArray)
static NSArray	flatten (NSArray<?> originalArray, boolean filterDuplicates)
static String	friendlyDisplayForKeyPath (NSArray<?> list, String attribute, String nullArrayDisplay, String separator, String finalSeparator)
static int	indexOfFirstObjectWithValueForKeyPath (NSArray<?> array, Object value, String keyPath)
static< T > int	indexOfObjectUsingEqualator (NSArray< T > array, T object, ERXEqualator equalator)
static void	initialize ()
static< T > NSArray< T >	intersectingElements (NSArray<?extends T > array1, NSArray<?extends T > array2)
static boolean	iteratorHasMatchWithQualifierEvaluation (Iterator<?> iterator, EOQualifierEvaluation qualifier)
static Number	median (NSArray<?> array, String keypath)
static String[]	objectArrayCastToStringArray (Object[] o)
static String	objectArraysToString (NSArray< Object[][]> array)
static String	objectArrayToString (Object[][] array)
static String	objectArrayToString (Object[] o)
static< T > NSArray< T >	objectsWithValueForKeyPath (final NSArray< T > array, final Object valueToLookFor, final String keyPath)
static< T > NSArray< T >	removeNullValues (NSArray< T > target, NSArray< T > array)
static< T > NSArray< T >	removeNullValues (NSArray< T > array)
static< T > NSArray< T >	removeNullValuesFromEnd (NSArray< T > array)
static< T > NSArray< T >	reverse (NSArray< T > array)
static< T > void	safeAddObject (NSMutableArray< T > array, T object)
static< T > NSSet< T >	setFromArray (NSArray< T > array)
static< T > void	shiftObjectLeft (NSMutableArray< T > array, T object)
static< T > void	shiftObjectRight (NSMutableArray< T > array, T object)
static void	sortArrayWithKey (NSMutableArray<?> array, String key, NSSelector selector)
static void	sortArrayWithKey (NSMutableArray<?> array, String key)
static< T > NSArray< T >	sortedArraySortedWithKey (NSArray< T > array, String key, NSSelector selector)
static< T > NSArray< T >	sortedArraySortedWithKey (NSArray< T > array, String key)
static< T > NSArray< T >	sortedArraySortedWithKeys (NSArray< T > array, NSArray< String > keys, NSSelector selector)
static< T > NSArray< T >	sortedArrayUsingComparator (final NSArray< T > array, final NSComparator comparator)
static< T > NSMutableArray< T >	sortedMutableArraySortedWithKey (NSArray< T > array, String key)
static NSSelector	sortSelectorWithKey (String key)
static Number	stdDev (NSArray<?> array, String keypath, boolean isPopulation)
static< T > void	swapObjectsAtIndexesInArray (NSMutableArray< T > array, int indexOfA, int indexOfB)
static< T > void	swapObjectsInArray (NSMutableArray< T > array, T a, T b)
static< T > void	swapObjectWithObjectAtIndexInArray (NSMutableArray< T > array, T a, int indexOfB)
static String[]	toStringArray (NSArray<?> a)
static NSArray	valuesForKeyPaths (Object array, NSArray< String > paths)
Static Public Attributes
static final String	NULL_GROUPING_KEY = "**** NULL GROUPING KEY ****"
Static Private Attributes
static final NSDictionary < String, NSSelector >	_selectorsByKey
static boolean	initialized = false
static Logger	log = Logger.getLogger(ERXArrayUtilities.class)

---

Detailed Description

Collection of NSArray utilities.

---

Member Function Documentation

static <T> void addObjectsFromArrayWithoutDuplicates	(	NSMutableArray< T >	a1,
		NSArray<?extends T >	a2
	)			[static]

Adds all of the non-duplicate elements from the second array to the mutable array.

Parameters:

	a1	mutable array where non-duplicate objects are added
	a2	array to be added to a1

static <T> NSArray<T> arrayByAddingObjectsFromArrayWithoutDuplicates	(	NSArray<?extends T >	a1,
		NSArray<?extends T >	a2
	)			[static]

Creates an array preserving order by adding all of the non-duplicate values from the second array to the first.

Parameters:

	a1	first array
	a2	second array

Returns:

array containing all of the elements of the first array and all of the non-duplicate elements of the second array.

static <T> NSArray<T> arrayByRemovingFirstObject

(

NSArray< T >

array

)

[static]

Creates an array that has all of the objects of the parameter array without the first object.

Parameters:

array

the array to use to create the result

Returns:

an array containing all objects but the first of the parameter array. if null is passed, null is returned. if the parameter array is empty, an empty array is returned.

static <T> NSArray<T> arrayBySelectingInstancesOfClass	(	final NSArray<?>	array,
		final Class< T >	aClass
	)			[static]

Prunes an array for only instances of the given class.

Parameters:

	array	array to process
	aClass	class to use. null results in the result being a copy of the array.

Returns:

an array which is a subset of the array where each object in the result is an instance of aClass.

static <T> boolean arrayContainsAnyObjectFromArray	(	NSArray<?extends T >	array,
		NSArray<?extends T >	objects
	)			[static]

Function to determine if an array contains any of the elements of another array.

Parameters:

	array	to test if it contains any of the objects
	objects	array of objects to test if the first array contains any of

Returns:

if the first array contains any elements from the second array

static <T> boolean arrayContainsArray	(	NSArray<?extends T >	array,
		NSArray<?extends T >	objects
	)			[static]

Function to determine if an array contains all of the elements of another array.

Parameters:

	array	to test if it contains all of the objects of another array
	objects	array of objects to test if the first array contains all of

Returns:

if the first array contains all of the elements from the second array

static NSArray<?> arrayForKeysPath	(	NSArray<?>	array,
		NSArray< String >	keys
	)			[static]

Returns an array of dictionaries containing the key/value pairs for the given paths.

Parameters:

	array	array of objects
	keys	array of keys

Returns:

array of dictionaries containing values for the key paths

static NSArray arrayFromPropertyList	(	String	name,
		NSBundle	bundle
	)			[static]

Creates an NSArray from a resource associated with a given bundle that is in property list format.

Parameters:

	name	name of the file or resource.
	bundle	NSBundle to which the resource belongs.

Returns:

NSArray de-serialized from the property list.

static NSDictionary arrayGroupedByKeyPath	(	NSArray	objects,
		String	keyPath,
		Object	nullGroupingKey,
		String	valueKeyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned. If valueKeyPath is not null, then the grouped arrays each have valueForKey called with valueKeyPath and the grouped arrays are replaced with the results of that call.

If one starts with:

( { lastName = "Barker"; firstName = "Bob"; favoriteColor = "blue"; },
{ firstName = "Bob"; favoriteColor = "red"; },
{ lastName = "Further"; firstName = "Frank"; favoriteColor = "green"; } )

and one calls arrayGroupedByKeyPath(objects, "firstName", null, "favoriteColor"), one gets:

{Frank = ("green"); Bob = ("blue", "red");

If one calls arrayGroupedByKeyPath(objects, "lastName", "extra", "favoriteColor"), one gets:

{Further = ("green"); Barker = ("blue"); "extra" = ("red"); }

If one calls arrayGroupedByKeyPath(objects, "lastName", null, "favoriteColor"), one gets:

{Further = ("green"); Barker = ("blue"); "**** NULL GROUPING KEY ****" = ("red"); }

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects
	nullGroupingKey	used as the key in the results dictionary for the array of objects for which the valueForKey with keyPath result is null.
	valueKeyPath	used to call valueForKey on the arrays in the results dictionary, with the results of those calls each replacing the corresponding array in the results dictionary.

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static <T,K,V> NSDictionary<K, NSArray<V> > arrayGroupedByKeyPath	(	NSArray< T >	objects,
		ERXKey< K >	keyPath,
		K	nullGroupingKey,
		ERXKey< V >	valueKeyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned. If valueKeyPath is not null, then the grouped arrays each have valueForKey called with valueKeyPath and the grouped arrays are replaced with the results of those calls. This is a typesafe variant of arrayGroupedByKeyPath(NSArray objects, String keyPath, Object nullGroupingKey, String valueKeyPath).

See arrayGroupedByKeyPath(NSArray objects, String keyPath, Object nullGroupingKey, String valueKeyPath) for examples.

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects
	nullGroupingKey	used as the key in the results dictionary for the array of objects for which the valueForKey with keyPath result is null.
	valueKeyPath	used to call valueForKey on the arrays in the results dictionary, with the results of those calls each replacing the corresponding array in the results dictionary.

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static <T,K,V> NSDictionary<K, NSArray<V> > arrayGroupedByKeyPath	(	NSArray< T >	objects,
		String	keyPath,
		boolean	includeNulls,
		String	valueKeyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned. If valueKeyPath is not null, then the grouped arrays each have valueForKey called with valueKeyPath and the grouped arrays are replaced with the results of those calls.

If one starts with:

( { lastName = "Barker"; firstName = "Bob"; favoriteColor = "blue"; },
{ firstName = "Bob"; favoriteColor = "red"; },
{ lastName = "Further"; firstName = "Frank"; favoriteColor = "green"; } )

and one calls arrayGroupedByKeyPath(objects, "firstName", true, "favoriteColor"), one gets:

{Frank = ("green"); Bob = ("blue", "red");

If one calls arrayGroupedByKeyPath(objects, "lastName", false, "favoriteColor"), one gets:

{Further = ("green"); Barker = ("blue"); }

If one calls arrayGroupedByKeyPath(objects, "lastName", true, "favoriteColor"), one gets:

{Further = ("green"); Barker = ("blue"); "**** NULL GROUPING KEY ****" = ("red"); }

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects
	includeNulls	determines if keyPaths that resolve to null are included in the resulting dictionary
	valueKeyPath	used to call valueForKey on the arrays in the results dictionary, with the results of those calls each replacing the corresponding array in the results dictionary.

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static <T,K,V> NSDictionary<K, NSArray<V> > arrayGroupedByKeyPath	(	NSArray< T >	objects,
		ERXKey< K >	keyPath,
		boolean	includeNulls,
		ERXKey< V >	valueKeyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned. If valueKeyPath is not null, then the grouped arrays each have valueForKey called with valueKeyPath and the grouped arrays are replaced with the results of those calls. This is a typesafe variant of arrayGroupedByKeyPath(NSArray<T> objects, String keyPath, boolean includeNulls, String valueKeyPath).

See arrayGroupedByKeyPath(NSArray<T> objects, String keyPath, boolean includeNulls, String valueKeyPath) for examples.

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects
	includeNulls	determines if keyPaths that resolve to null are included in the resulting dictionary
	valueKeyPath	used to call valueForKey on the arrays in the results dictionary, with the results of those calls each replacing the corresponding array in the results dictionary.

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByKeyPath	(	NSArray< V >	objects,
		String	keyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned.

If one starts with:

( { lastName = "Barker"; firstName = "Bob"; favoriteColor = "blue"; },
{ firstName = "Bob"; favoriteColor = "red"; },
{ lastName = "Further"; firstName = "Frank"; favoriteColor = "green"; } )

and one calls arrayGroupedByKeyPath(objects, "firstName"), one gets:

{ "Bob" = ( { lastName = "Barker"; firstName = "Bob"; favoriteColor = "blue"; }, { firstName = "Bob"; favoriteColor = "red"; } );
"Frank" = ( { lastName = "Further"; firstName = "Frank"; favoriteColor = "green"; } ); }

If one calls arrayGroupedByKeyPath(objects, "lastName"), one gets:

{ "Bob" = ( { lastName = "Barker"; firstName = "Bob"; favoriteColor = "blue"; } );
"Frank" = ( { lastName = "Further"; firstName = "Frank"; favoriteColor = "green"; } );
"**** NULL GROUPING KEY ****" = ( { firstName = "Bob"; favoriteColor = "red"; } ); }

This method calls arrayGroupedByKeyPath(objects, keyPath, includeNulls, valueKeyPath) with includeNulls set to true and valueKeyPath set to null.

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByKeyPath	(	NSArray< V >	objects,
		ERXKey< K >	keyPath
	)			[static]

Starting with an array of KeyValueCoding-compliant objects and a keyPath, this method calls valueForKey on each object in the array and groups the contents of the array, using the result of the valueForKey call as a key in a dictionary. If passed a null array, null is returned. If passed a null keyPath, an empty dictionary is returned. This is a typesafe variant of arrayGroupedByKeyPath(NSArray<V> objects, String keyPath).

See arrayGroupedByKeyPath(NSArray<V> objects, String keyPath) for examples.

This method calls arrayGroupedByKeyPath(NSArray objects, String keyPath, Object nullGroupingKey, String valueKeyPath) with includeNulls set to true and valueKeyPath set to null.

Parameters:

	objects	array of objects to be grouped
	keyPath	path into objects used to group the objects

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have that value. Objects for which the key path returns null will be grouped with the key NULL_GROUPING_KEY

static NSDictionary arrayGroupedByToManyKeyPath	(	NSArray	objects,
		String	keyPath,
		Object	nullGroupingKey,
		String	valueKeyPath
	)			[static]

Groups an array of objects by a given to-many key path, where every single item in the to-many will put the object in the corresponding group. The dictionary that is returned contains keys that correspond to the grouped keys values. This means that the object pointed to by the key path must be a cloneable object. For instance using the key path 'users' would not work because enterprise objects are not cloneable. Instead you might choose to use the key path 'users.name' of 'users.primaryKey', if your enterprise objects support this see ERXGenericRecord if interested.

Parameters:

	objects	array of objects to be grouped
	keyPath	path used to group the objects.
	nullGroupingKey	if not-null, determines if keyPaths that resolve to null should be allowed into the group; if so, this key is used for them
	valueKeyPath	allows the grouped objects in the result to be derived from objects (by evaluating valueKeyPath), instead of being members of the objects collection. Objects that evaluate valueKeyPath to null have no value included in the result

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have the grouped characteristic. Note that if the key path returns null then one of the keys will be the static ivar NULL_GROUPING_KEY

static <T,K,V> NSDictionary<K, NSArray<V> > arrayGroupedByToManyKeyPath	(	NSArray< T >	objects,
		ERXKey< K >	keyPath,
		K	nullGroupingKey,
		ERXKey< V >	valueKeyPath
	)			[static]

Typesafe variant of arrayGroupedByToManyKeyPath.

Parameters:

	objects	array of objects to be grouped
	keyPath	path used to group the objects.
	nullGroupingKey	if not-null, determines if keyPaths that resolve to null should be allowed into the group; if so, this key is used for them
	valueKeyPath	allows the grouped objects in the result to be derived from objects (by evaluating valueKeyPath), instead of being members of the objects collection. Objects that evaluate valueKeyPath to null have no value included in the result

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have the grouped characteristic. Note that if the key path returns null then one of the keys will be the static ivar NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByToManyKeyPath	(	NSArray< V >	objects,
		String	keyPath,
		K	nullGroupingKey
	)			[static]

Groups an array of objects by a given to-many key path, where every single item in the to-many will put the object in the corresponding group. The dictionary that is returned contains keys that correspond to the grouped keys values. This means that the object pointed to by the key path must be a cloneable object. For instance using the key path 'users' would not work because enterprise objects are not cloneable. Instead you might choose to use the key path 'users.name' of 'users.primaryKey', if your enterprise objects support this see ERXGenericRecord if interested.

Parameters:

	objects	array of objects to be grouped
	keyPath	path used to group the objects.
	nullGroupingKey	if not-null, determines if keyPaths that resolve to null should be allowed into the group; if so, this key is used for them

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have the grouped characteristic. Note that if the key path returns null then one of the keys will be the static ivar NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByToManyKeyPath	(	NSArray< V >	objects,
		ERXKey< K >	keyPath,
		K	nullGroupingKey
	)			[static]

Typesafe variant of arrayGroupedByToManyKeyPath.

Parameters:

	objects	array of objects to be grouped
	keyPath	path used to group the objects.
	nullGroupingKey	if not-null, determines if keyPaths that resolve to null should be allowed into the group; if so, this key is used for them

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have the grouped characteristic. Note that if the key path returns null then one of the keys will be the static ivar NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByToManyKeyPath	(	NSArray< V >	objects,
		String	keyPath,
		boolean	includeNulls
	)			[static]

Groups an array of objects by a given to-many key path, where every single item in the to-many will put the object in the corresponding group. A typical example is an array of users with a roles relationship. The result to calling arrayGroupedByToManyKeyPath(users, "roles.name") would be "admin" = (user1, user2); "editor" = (user3);.... The dictionary that is returned contains keys that correspond to the grouped keys values. This means that the object pointed to by the key path must be a cloneable object. For instance using the key path 'users' would not work because enterprise objects are not cloneable. Instead you might choose to use the key path 'users.name' of 'users.primaryKey', if your enterprise objects support this see ERXGenericRecord if interested.

Parameters:

	objects	array of objects to be grouped
	keyPath	path used to group the objects.
	includeNulls	determines if keyPaths that resolve to null should be allowed into the group.

Returns:

a dictionary where the keys are the grouped values and the objects are arrays of the objects that have the grouped characteristic. Note that if the key path returns null then one of the keys will be the static ivar NULL_GROUPING_KEY

static <K,V> NSDictionary<K, NSArray<V> > arrayGroupedByToManyKeyPath	(	NSArray< V >	objects,
		ERXKey< K >	keyPath,
		boolean	includeNulls
	)			[static]

Typesafe variant of arrayGroupedByToManyKeyPath.

Parameters:

	objects	the objects to be grouped
	keyPath	the key to group by
	includeNulls	determins if the keypaths that resolve to null should be allowed in the group

Returns:

the resulting dictionary

static <T> NSArray<T> arrayMinusArray	(	NSArray< T >	main,
		NSArray<?>	minus
	)			[static]

Subtracts the contents of one array from another. The order of the array should be preseved.

Parameters:

	main	array to have values removed from it.
	minus	array of values to remove from the main array

Returns:

array after performing subtraction.

static <T> NSArray<T> arrayMinusObject	(	NSArray< T >	main,
		Object	object
	)			[static]

Subtracts a single object from an array.

Parameters:

	main	array to have value removed from it.
	object	to be removed

Returns:

array after performing subtraction.

static <T> boolean arraysAreIdenticalSets	(	NSArray<?super T >	a1,
		NSArray<?super T >	a2
	)			[static]

Simple comparision method to see if two array objects are identical sets.

Parameters:

	a1	first array
	a2	second array

Returns:

result of comparison

static <T> NSArray<T> arrayWithObjectsAtIndexesSwapped	(	final NSArray< T >	array,
		final int	indexOfObject1,
		final int	indexOfObject2
	)			[static]

Swaps the two objects at the given indexes in the given NSArray and returns a new NSArray.

Author:

edgar - Jan 7, 2008

Parameters:

	array	in that the two Objects at the given indexes have to be swapped
	indexOfObject1	index of one object in the NSArray that will be swapped
	indexOfObject2	index of the other object in the NSArray that will be swapped

Returns:

the new NSArray with the swapped elements

Exceptions:

{@link

RuntimeException} if one of the indexes is out of bound

static <T> NSArray<T> arrayWithObjectsSwapped	(	final NSArray< T >	array,
		final Object	object1,
		final Object	object2
	)			[static]

Swaps the two given Objects in the given NSArray and returns a new NSArray. If one of the Objects is not element of the NSArray a RuntimeException will be thrown.

Author:

edgar - Jan 7, 2008

Parameters:

	<T>
	array	in that the two given Objects have to be swapped
	object1	one object in the NSArray that will be swapped
	object2	the other object in the NSArray that will be swapped

Returns:

the new NSArray with the swapped elements

Exceptions:

{@link

RuntimeException} if one of the Objects is not in the NSArray

static <T> NSArray<T> arrayWithoutDuplicateKeyValue	(	NSArray< T >	objects,
		String	key
	)			[static]

Filters out duplicates of an array of objects based on the value of the given key path off of those objects. Objects with a null value will be skipped, too.

Parameters:

	objects	array of objects
	key	keypath to be evaluated off of every object

Returns:

filter array of objects based on the value of a keypath.

static <T> NSArray<T> arrayWithoutDuplicates

(

NSArray< T >

anArray

)

[static]

Filters out all of the duplicate objects in a given array.
Preserves the order now.

Parameters:

anArray

to be filtered

Returns:

filtered array.

static <T> NSArray<NSArray<T> > batchedArrayWithSize	(	NSArray< T >	array,
		int	batchSize
	)			[static]

Batches an NSArray into sub-arrays of the given size.

Parameters:

	array	array to batch
	batchSize	number of items in each batch

Returns:

NSArray of NSArrays, each with at most batchSize items

static <T> NSSet<T> deepClone	(	NSSet< T >	set,
		boolean	onlyCollections
	)			[static]

Returns a deep clone of the given set. A deep clone will attempt to clone the values of this set as well as the set itself.

Parameters:

	set	the set to clone
	onlyCollections	if true, only collections in this array will be cloned, not individual values

Returns:

a deep clone of set

static <T> NSArray<T> deepClone	(	NSArray< T >	array,
		boolean	onlyCollections
	)			[static]

Returns a deep clone of the given array. A deep clone will attempt to clone the values of this array as well as the array itself.

Parameters:

	array	the array to clone
	onlyCollections	if true, only collections in this array will be cloned, not individual values

Returns:

a deep clone of array

static <K,T> NSDictionary<K, T> dictionaryOfObjectsIndexedByKeyPath	(	final NSArray< T >	array,
		final String	keyPath
	)			[static]

Calls dictionaryOfObjectsIndexedByKeyPathThrowOnCollision() passing false for throwOnCollision.

static <K,T> NSDictionary<K, T> dictionaryOfObjectsIndexedByKeyPathThrowOnCollision	(	final NSArray< T >	array,
		final String	keyPath,
		final boolean	throwOnCollision
	)			[static]

Given an array of objects, returns a dictionary mapping the value by performing valueForKeyPath on each object in the array to the object in the array. This is similar in concept to but different in semantic from arrayGroupedByKeyPath(). That method is focused on multiple objects returning the same value for the keypath and, so, objects are grouped into arrays. That is not particularly useful when there aren't collisions in the array or when you don't care if there are collisions. For example, with a CreditCard EO object, one could rely on the paymentType.name value to be unique and thus you're more interested in being able to rapidly get to the EO. arrayGroupedByKeyPath() would require either flattening out the arrays or navigating them everytime.

Parameters:

	array	array to index
	keyPath	keyPath to index. if any object returns null of NSKeyValueCoding.NullValue for this keyPath, the object is not put into the resulting dictionary.
	throwOnCollision	if true and two objects in the array have the same non-null (or non-NullValue) value for keyPath, an exception is thrown. if false, the last object in the array wins.

Returns:

a dictionary indexing the given array. if array is null, an empty dictionary is returned.

static <T> NSArray<T> distinct

(

NSArray< T >

array

)

[static]

Shorter name for arrayWithoutDuplicates, which I always forget the name of.

Parameters:

	<T>	type of the array
	array	the array to return distinct values from

Returns:

an array of distinct elements from the input array

static boolean enumerationHasMatchWithQualifierEvaluation	(	Enumeration<?>	enumeration,
		EOQualifierEvaluation	qualifier
	)			[static]

Filters any kinds of collections that implements Enumeration interface such as NSArray, NSSet, Vector and Hashtable using the EOQualifierEvaluation interface.

Parameters:

	enumeration	to be filtered; to obtain an enumeration, use objectEnumerator() for the collections in com.webobjects.foundation package and use elements() for the Vector and Hashtable
	qualifier	to do the filtering

Returns:

true if there is at least one match

static <T> NSArray<T> filteredArrayWithEntityFetchSpecification	(	NSArray< T >	array,
		String	entity,
		String	fetchSpec
	)			[static]

Filters a given array with a named fetch specification.

Parameters:

	array	array to be filtered.
	fetchSpec	name of the EOQualifierEvaluation.
	entity	name of the EOEntity to which the fetch specification is associated.

Returns:

array filtered and sorted by the named fetch specification.

static <T> NSArray<T> filteredArrayWithEntityFetchSpecification	(	NSArray< T >	array,
		String	entity,
		String	fetchSpec,
		NSDictionary< String,?>	bindings
	)			[static]

Filters a given array with a named fetch specification and bindings.

Parameters:

	array	array to be filtered.
	fetchSpec	name of the EOQualifierEvaluation.
	entity	name of the EOEntity to which the fetch specification is associated.
	bindings	bindings dictionary for qualifier variable substitution.

Returns:

array filtered and sorted by the named fetch specification.

static <T> NSArray<T> filteredArrayWithFetchSpecificationNamedEntityNamed	(	NSArray< T >	array,
		String	fetchSpec,
		String	entity
	)			[static]

Deprecated:

static <T> NSArray<T> filteredArrayWithFetchSpecificationNamedEntityNamedBindings	(	NSArray< T >	array,
		String	fetchSpec,
		String	entity,
		NSDictionary< String,?>	bindings
	)			[static]

Deprecated:

static <T> NSArray<T> filteredArrayWithQualifierEvaluation	(	Iterator< T >	iterator,
		EOQualifierEvaluation	qualifier
	)			[static]

Filters any kind of collections that implements Iterator interface such as ArrayList, HashMap, SortedSet and TreeSet using the EOQualifierEvaluation interface.

Parameters:

	iterator	to be filtered; use iterator() to obtain an iterator from the collections
	qualifier	to do the filtering

Returns:

array of filtered results.

static <T> NSArray<T> filteredArrayWithQualifierEvaluation	(	Enumeration< T >	enumeration,
		EOQualifierEvaluation	qualifier
	)			[static]

Filters any kinds of collections that implements Enumeration interface such as NSArray, NSSet, Vector and Hashtable using the EOQualifierEvaluation interface.

Parameters:

	enumeration	to be filtered; to obtain an enumeration, use objectEnumerator() for the collections in com.webobjects.foundation package and use elements() for the Vector and Hashtable
	qualifier	to do the filtering

Returns:

array of filtered results.

static <T> NSArray<T> filteredArrayWithQualifierEvaluation	(	NSArray< T >	array,
		EOQualifierEvaluation	qualifier
	)			[static]

Filters an array using the EOQualifierEvaluation interface.

Parameters:

	array	to be filtered
	qualifier	to do the filtering

Returns:

array of filtered results.

static <T> T firstObject

(

NSArray< T >

array

)

[static]

Returns the first object of the array. If the array is null or empty, null is returned.

Parameters:

array

the array to search.

Returns:

the first object in array. null if array is empty or if array is null.

static <T> T firstObjectWithValueForKeyPath	(	NSArray< T >	array,
		Object	value,
		String	keyPath
	)			[static]

Finds the first object in the array with a given value for a given key path.

Parameters:

	array	the array to search.
	value	the value to look for.
	keyPath	the keypath to use to compare to value.

Returns:

first object in the array with the qualification. null if none matches.

static NSArray flatten

(

NSArray<?>

originalArray

)

[static]

Recursively flattens an array of arrays and individual objects into a single array of elements.

For example:
NSArray foos; //Assume exists
NSArray bars = (NSArray)foos.valueForKey("toBars"); In this case if foos contained five elements then the array bars will contain five arrays each corresponding to what aFoo.toBars would return. To have the entire collection of bars in one single array you would call: NSArray allBars = flatten(bars)

Parameters:

originalArray

array to be flattened

Returns:

an array containing all of the elements from all of the arrays contained within the array passed in.

static NSArray flatten	(	NSArray<?>	originalArray,
		boolean	filterDuplicates
	)			[static]

Recursively flattens an array of arrays and individual objects into a single array of elements.

For example:
NSArray foos; //Assume exists
NSArray bars = (NSArray)foos.valueForKey("toBars"); In this case if foos contained five elements then the array bars will contain five arrays each corresponding to what aFoo.toBars would return. To have the entire collection of bars in one single array you would call: NSArray allBars = flatten(bars)

Parameters:

	originalArray	array to be flattened
	filterDuplicates	determines if the duplicate values should be filtered

Returns:

an array containing all of the elements from all of the arrays contained within the array passed in. (Optionally, with duplicate elements filtered out)

static String friendlyDisplayForKeyPath	(	NSArray<?>	list,
		String	attribute,
		String	nullArrayDisplay,
		String	separator,
		String	finalSeparator
	)			[static]

Displays a list of attributes off of objects in a 'friendly' manner.

For example, given an array containing three user objects and the attribute key "firstName", the result of calling this method would be the string: "Max, Anjo and Patrice".

Parameters:

	list	of objects to be displayed in a friendly manner
	attribute	key to be called on each object in the list
	nullArrayDisplay	string to be returned if the list is null or empty
	separator	string to be used for the first items
	finalSeparator	used between the last items

Returns:

friendly display string

static int indexOfFirstObjectWithValueForKeyPath	(	NSArray<?>	array,
		Object	value,
		String	keyPath
	)			[static]

Finds the index of the first object in the array with a given value for a given keypath. Assumes that all objects in the array either are NSKeyValueCoding.NullValue or have the given keypath.

Parameters:

	array	the array to search.
	value	the value to look for.
	keyPath	the keypath to use to compare to value.

Returns:

index of the first object with the qualification. -1 if none matches.

static <T> int indexOfObjectUsingEqualator	(	NSArray< T >	array,
		T	object,
		ERXEqualator	equalator
	)			[static]

Locates an object within an array using a custom equality check provided as an ERXEqualator. This is useful if you have an array of EOs and want to find a particular EO in it without regard to editing contexts.

Parameters:

	array	the array to search.
	object	the object to look for.
	equalator	the equalator to use for performing the equality check between object and each object in the array.

Returns:

index of first occuring object in the array that is defined as equal by the equalator. -1 if no such object is found.

static void initialize

(

)

[static]

Will register new NSArray operators sort, sortAsc, sortDesc, sortInsensitiveAsc, sortInsensitiveDesc, unique, flatten, reverse, limit, and fetchSpec

static <T> NSArray<T> intersectingElements	(	NSArray<?extends T >	array1,
		NSArray<?extends T >	array2
	)			[static]

Intersects the elements of two arrays. This has the effect of stripping out duplicates.

Parameters:

	array1	the first array
	array2	the second array

Returns:

the intersecting elements

static boolean iteratorHasMatchWithQualifierEvaluation	(	Iterator<?>	iterator,
		EOQualifierEvaluation	qualifier
	)			[static]

Filters any kinds of collections that implements Iterator interface such as NSArray, NSSet, Vector and Hashtable using the EOQualifierEvaluation interface.

Parameters:

	iterator	to be filtered; to obtain an iterator, use iterator() for the java collections
	qualifier	to do the filtering

Returns:

true if there is at least one match

static Number median	(	NSArray<?>	array,
		String	keypath
	)			[static]

Calculates the median value of an array. The median is the value for which half of the elements are above and half the elements are below. As such, an array sort is needed and this might be very costly depending of the size of the array.

Parameters:

	array	array of objects
	keypath	key path for the median

Returns:

the median value

static String [] objectArrayCastToStringArray

(

Object[]

o

)

[static]

Converts an Object array to a String array by casting each element. This is analogus to String[] myStringArray = (String[])myObjectArray; except that it creates a clone of the array.

Parameters:

o

an Object array containing String elements

Returns:

a String array containing the same elements

static String objectArraysToString

(

NSArray< Object[][]>

array

)

[static]

pretty prints a NSArray of two dimensional Object array which is ugly when using toString

Parameters:

array

the object which one wants to print as a String

Returns:

the String which can be used in lets say log.info("my array = "+ERXArrayUtilities.objectArrayToString(myArray));

static String objectArrayToString

(

Object

array[][]

)

[static]

pretty prints a two dimensional Object array which is ugly when using toString

Parameters:

array

the object which one wants to print as a String

Returns:

the String which can be used in lets say log.info("my array = "+ERXArrayUtilities.objectArrayToString(myArray));

static String objectArrayToString

(

Object[]

o

)

[static]

pretty prints an Object array which is ugly when using toString

Parameters:

o

the object which one wants to print as a String

Returns:

the String which can be used in lets say log.info("my array = "+ERXArrayUtilities.objectArrayToString(myArray));

static <T> NSArray<T> objectsWithValueForKeyPath	(	final NSArray< T >	array,
		final Object	valueToLookFor,
		final String	keyPath
	)			[static]

Walks over an array and returns an array of objects from that array that have a particular value for a particular key path. Treats null and NSKeyValueCoding.NullValue equivalently. Any NSKeyValueCoding.NullValue objects in the array are skipped. If array is null or empty, an empty array is returned.

Parameters:

	array	array to search
	valueToLookFor	value to look for
	keyPath	key path to apply on each object on the array to compare against valueToLookFor

Returns:

an array of matching objects

static <T> NSArray<T> removeNullValues	(	NSArray< T >	target,
		NSArray< T >	array
	)			[static]

Removes all occurencies of NSKeyValueCoding.NullValue in the provided array

Parameters:

	target	array to remove objects from
	array	array of values

Returns:

a new NSArray with the same order than the original array but without NSKeyValueCoding.NullValue objects

static <T> NSArray<T> removeNullValues

(

NSArray< T >

array

)

[static]

Removes all occurencies of NSKeyValueCoding.NullValue in the provided array

Parameters:

array

the array from which the NullValue should be removed

Returns:

a new NSArray with the same order than the original array but without NSKeyValueCoding.NullValue objects

static <T> NSArray<T> removeNullValuesFromEnd

(

NSArray< T >

array

)

[static]

removes all occurencies of NSKeyValueCoding.Null from the end of the array

Parameters:

array

the array from which the values should be removed

Returns:

a new NSArray which does not have NSKeyValueCoding.Null instances at the end

static <T> NSArray<T> reverse

(

NSArray< T >

array

)

[static]

Reverses the elements of an array

Parameters:

array

to be reversed

Returns:

reverse ordered array

static <T> void safeAddObject	(	NSMutableArray< T >	array,
		T	object
	)			[static]

Adds the object to the mutable array if the object is not null.

Parameters:

	array	mutable array where non-null object will be added
	object	to be added to array

static <T> NSSet<T> setFromArray

(

NSArray< T >

array

)

[static]

Simply utility method to create a concrete set object from an array.

Parameters:

array

of elements

static <T> void shiftObjectLeft	(	NSMutableArray< T >	array,
		T	object
	)			[static]

shifts a given object in an array one value to the left (index--).

Parameters:

	array	array to be modified.
	object	the object that should be moved

static <T> void shiftObjectRight	(	NSMutableArray< T >	array,
		T	object
	)			[static]

shifts a given object in an array one value to the right (index++).

Parameters:

	array	array to be modified.
	object	the object that should be moved

static void sortArrayWithKey	(	NSMutableArray<?>	array,
		String	key,
		NSSelector	selector
	)			[static]

Sorts a given mutable array with a key in place.

Parameters:

	array	array to be sorted.
	key	sort key.
	selector	sort order selector to use, if null, then sort will be ascending.

static void sortArrayWithKey	(	NSMutableArray<?>	array,
		String	key
	)			[static]

Sorts a given mutable array with a key in place.

Parameters:

	array	array to be sorted.
	key	sort key.

static <T> NSArray<T> sortedArraySortedWithKey	(	NSArray< T >	array,
		String	key,
		NSSelector	selector
	)			[static]

Sorts a given array with a key in ascending fashion.

Parameters:

	array	array to be sorted.
	key	sort key.
	selector	sort order selector to use, if null, then sort will be case insensitive ascending.

Returns:

sorted array.

static <T> NSArray<T> sortedArraySortedWithKey	(	NSArray< T >	array,
		String	key
	)			[static]

Sorts a given array with a key in ascending fashion.

Parameters:

	array	array to be sorted.
	key	sort key.

Returns:

mutable clone of sorted array.

static <T> NSArray<T> sortedArraySortedWithKeys	(	NSArray< T >	array,
		NSArray< String >	keys,
		NSSelector	selector
	)			[static]

Sorts a given array with a set of keys according to the given selector.

Parameters:

	array	array to be sorted.
	keys	sort keys
	selector	sort order selector to use, if null, then sort will be case insensitive ascending.

Returns:

sorted array.

static <T> NSArray<T> sortedArrayUsingComparator	(	final NSArray< T >	array,
		final NSComparator	comparator
	)			[static]

Just like the method NSArray#sortedArrayUsingComparator(NSComparator), except it catches the NSComparator.ComparisonException and, if thrown, it wraps it in a runtime exception. Returns null when passed null for array.

Parameters:

	array
	comparator
	<T>

Returns:

the sorted array

static <T> NSMutableArray<T> sortedMutableArraySortedWithKey	(	NSArray< T >	array,
		String	key
	)			[static]

Sorts a given array with a key in ascending fashion and returns a mutable clone of the result.

Parameters:

	array	array to be sorted.
	key	sort key.

Returns:

mutable clone of sorted array.

static NSSelector sortSelectorWithKey

(

String

key

)

[static]

The qualifiers EOSortOrdering.CompareAscending.. and friends are actually 'special' and processed in a different/faster way when sorting than a selector that would be created by: new NSSelector("compareAscending", ObjectClassArray) This method eases the pain on creating those selectors from a string.

Parameters:

key

sort key

static Number stdDev	(	NSArray<?>	array,
		String	keypath,
		boolean	isPopulation
	)			[static]

Finds the standard deviation of the numeric values found in the array at the specified keypath. If the keypath is null or empty, then the array values are used instead. If the array has fewer than two objects, null is returned. If isPopulation is true, the population standard deviation is calculated. If isPopulation is false, the sample standard deviation is calculated. Use a true value for isPopulation if you know the values for an entire population and false if you are dealing with a sample.

Parameters:

	array	an array of objects
	keypath	a key path to a numeric value on each object
	isPopulation

Returns:

the standard deviation for the numeric values

static <T> void swapObjectsAtIndexesInArray	(	NSMutableArray< T >	array,
		int	indexOfA,
		int	indexOfB
	)			[static]

Swaps two objects at the given indexes in an array inplace

Author:

cug - Jan 7, 2008

Parameters:

	array	the array
	indexOfA	- index of the first object
	indexOfB	- index of the second object

Exceptions:

{@link

RuntimeException} if one or both indexes are out of bounds

static <T> void swapObjectsInArray	(	NSMutableArray< T >	array,
		T	a,
		T	b
	)			[static]

Swaps two objects a and b in an array inplace

Author:

cug - Jan 7, 2008

Parameters:

	array	the array
	a	- first object
	b	- second object

Exceptions:

{@link

RuntimeException} if one or both indexes are out of bounds

static <T> void swapObjectWithObjectAtIndexInArray	(	NSMutableArray< T >	array,
		T	a,
		int	indexOfB
	)			[static]

Swaps the object a with the object at the given index

Author:

edgar - Apr 14, 2008

Parameters:

	array	the array
	a	- first object
	indexOfB	- index of second object

static String [] toStringArray

(

NSArray<?>

a

)

[static]

static NSArray valuesForKeyPaths	(	Object	array,
		NSArray< String >	paths
	)			[static]

Performs multiple key-value coding calls against an array or an object.

Parameters:

	array	collection or object to be acted upon.
	paths	array of keypaths.

Returns:

for collections, returns an array containing an array of values for every keypath. For objects, returns an array containing a value for every keypath.

---

Member Data Documentation

final NSDictionary<String, NSSelector> _selectorsByKey [static, private]

Initial value:

new NSDictionary<String, NSSelector>(new NSSelector [] {
        EOSortOrdering.CompareAscending,
        EOSortOrdering.CompareCaseInsensitiveAscending,
        EOSortOrdering.CompareCaseInsensitiveDescending,
        EOSortOrdering.CompareDescending,
    }, new String [] {
        "compareAscending",
        "compareCaseInsensitiveAscending",
        "compareCaseInsensitiveDescending",
        "compareDescending",
    })

Caches sort orderings for given keys

boolean initialized = false [static, private]

caches if array utilities have been initialized

Logger log = Logger.getLogger(ERXArrayUtilities.class) [static, private]

final String NULL_GROUPING_KEY = "**** NULL GROUPING KEY ****" [static]

Holds the null grouping key for use when grouping objects based on a key that might return null and nulls are allowed

---

The documentation for this class was generated from the following file:

• /opt/source/Wonder/Frameworks/Core/ERExtensions/Sources/er/extensions/foundation/ERXArrayUtilities.java