Package com.okta.commons.lang

Class Collections

java.lang.Object

com.okta.commons.lang.Collections

public abstract class Collections
extends java.lang.Object

Constructor Summary

Constructors

Constructor	Description
Collections()

Method Summary

Modifier and Type	Method	Description
static java.util.List	arrayToList(java.lang.Object source)	Convert the supplied array into a List.
static boolean	contains(java.util.Enumeration enumeration, java.lang.Object element)	Check whether the given Enumeration contains the given element.
static boolean	contains(java.util.Iterator iterator, java.lang.Object element)	Check whether the given Iterator contains the given element.
static boolean	containsAny(java.util.Collection source, java.util.Collection candidates)	Return true if any element in 'candidates' is contained in 'source'; otherwise returns false.
static boolean	containsInstance(java.util.Collection collection, java.lang.Object element)	Check whether the given Collection contains the given element instance.
static java.lang.Class<?>	findCommonElementType(java.util.Collection collection)	Find the common element type of the given Collection, if any.
static java.lang.Object	findFirstMatch(java.util.Collection source, java.util.Collection candidates)	Return the first element in 'candidates' that is contained in 'source'.
static <T> T	findFirstValueOfType(java.util.Collection<?> collection, java.lang.Class<T> type)	Find the first single value of the given type in the given Collection or null if none was found
static java.lang.Object	findValueOfType(java.util.Collection<?> collection, java.lang.Class<?>[] types)	Find a single value of one of the given types in the given Collection: searching the Collection for a value of the first type, then searching for a value of the second type, etc.
static boolean	hasUniqueObject(java.util.Collection collection)	Determine whether the given Collection only contains a single unique object.
static boolean	isEmpty(java.util.Collection collection)	Return true if the supplied Collection is null or empty.
static boolean	isEmpty(java.util.Map map)	Return true if the supplied Map is null or empty.
static void	mergeArrayIntoCollection(java.lang.Object array, java.util.Collection collection)	Merge the given array into the given Collection.
static void	mergePropertiesIntoMap(java.util.Properties props, java.util.Map map)	Merge the given Properties instance into the given Map, copying all properties (key-value pairs) over.
static int	size(java.util.Collection collection)	Returns the collection's size or 0 if the collection is null.
static int	size(java.util.Map map)	Returns the map's size or 0 if the map is null.
static <T> T[]	toArray(java.util.Collection<T> c, java.lang.Class<T> type)
static <A,E extends A> A[]	toArray(java.util.Enumeration<E> enumeration, A[] array)	Marshal the elements from the given enumeration into an array of the given type.
static <E> java.util.Iterator<E>	toIterator(java.util.Enumeration<E> enumeration)	Adapt an enumeration to an iterator.
static <T> java.util.List<T>	toList(java.util.Collection<T> elements)	a new List that contains the specified elements or an empty collection if the elements are null or empty.
static <T> java.util.List<T>	toList(T... elements)	a new List that contains the specified elements or an empty collection if the elements are null or empty.
static <E> java.util.Set<E>	toSet(E... elements)	Returns a new Set that contains the specified elements or an empty Set if the elements are null or empty.

Methods inherited from class java.lang.Object

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

Constructor Detail

Collections

public Collections()

Method Detail

isEmpty

public static boolean isEmpty(java.util.Collection collection)

Return true if the supplied Collection is null or empty. Otherwise, return false.

Parameters:

collection - the Collection to check

Returns:

whether the given Collection is empty

size

public static int size(java.util.Collection collection)

Returns the collection's size or 0 if the collection is null.

Parameters:

collection - the collection to check.

Returns:

the collection's size or 0 if the collection is null.

size

public static int size(java.util.Map map)

Returns the map's size or 0 if the map is null.

Parameters:

map - the map to check

Returns:

the map's size or 0 if the map is null.

isEmpty

public static boolean isEmpty(java.util.Map map)

Return true if the supplied Map is null or empty. Otherwise, return false.

Parameters:

map - the Map to check

Returns:

whether the given Map is empty

arrayToList

public static java.util.List arrayToList(java.lang.Object source)

Convert the supplied array into a List. A primitive array gets converted into a List of the appropriate wrapper type.

A null source value will be converted to an empty List.

Parameters:

source - the (potentially primitive) array

Returns:

the converted List result

See Also:

Objects.toObjectArray(Object)

toList

public static <T> java.util.List<T> toList(T... elements)

a new List that contains the specified elements or an empty collection if the elements are null or empty.

Type Parameters:

T - the type of elements in the collection

Parameters:

elements - the elements to put in the list.

Returns:

a new List that contains the specified elements or an empty collection if the elements are null or empty.

toList

public static <T> java.util.List<T> toList(java.util.Collection<T> elements)

a new List that contains the specified elements or an empty collection if the elements are null or empty.

Type Parameters:

T - the type of elements in the collection

Parameters:

elements - the elements to put in the list.

Returns:

a new List that contains the specified elements or an empty collection if the elements are null or empty.

toSet

public static <E> java.util.Set<E> toSet(E... elements)

Returns a new Set that contains the specified elements or an empty Set if the elements are null or empty.

Type Parameters:

E - the type of elements in the set

Parameters:

elements - elements to add to the new set

Returns:

a new Set that contains the specified elements or an empty Set if the elements are null or empty.

mergeArrayIntoCollection

public static void mergeArrayIntoCollection(java.lang.Object array,
                                            java.util.Collection collection)

Merge the given array into the given Collection.

Parameters:

array - the array to merge (may be null)

collection - the target Collection to merge the array into

mergePropertiesIntoMap

public static void mergePropertiesIntoMap(java.util.Properties props,
                                          java.util.Map map)

Merge the given Properties instance into the given Map, copying all properties (key-value pairs) over.

Uses Properties.propertyNames() to even catch default properties linked into the original Properties instance.

Parameters:

props - the Properties instance to merge (may be null)

map - the target Map to merge the properties into

contains

public static boolean contains(java.util.Iterator iterator,
                               java.lang.Object element)

Check whether the given Iterator contains the given element.

Parameters:

iterator - the Iterator to check

element - the element to look for

Returns:

true if found, false else

contains

public static boolean contains(java.util.Enumeration enumeration,
                               java.lang.Object element)

Check whether the given Enumeration contains the given element.

Parameters:

enumeration - the Enumeration to check

element - the element to look for

Returns:

true if found, false else

containsInstance

public static boolean containsInstance(java.util.Collection collection,
                                       java.lang.Object element)

Check whether the given Collection contains the given element instance.

Enforces the given instance to be present, rather than returning true for an equal element as well.

Parameters:

collection - the Collection to check

element - the element to look for

Returns:

true if found, false else

containsAny

public static boolean containsAny(java.util.Collection source,
                                  java.util.Collection candidates)

Return true if any element in 'candidates' is contained in 'source'; otherwise returns false.

Parameters:

source - the source Collection

candidates - the candidates to search for

Returns:

whether any of the candidates has been found

findFirstMatch

public static java.lang.Object findFirstMatch(java.util.Collection source,
                                              java.util.Collection candidates)

Return the first element in 'candidates' that is contained in 'source'. If no element in 'candidates' is present in 'source' returns null. Iteration order is Collection implementation specific.

Parameters:

source - the source Collection

candidates - the candidates to search for

Returns:

the first present object, or null if not found

findFirstValueOfType

public static <T> T findFirstValueOfType(java.util.Collection<?> collection,
                                         java.lang.Class<T> type)

Find the first single value of the given type in the given Collection or null if none was found

Type Parameters:

T - type type of object to find

Parameters:

collection - the Collection to search

type - the type to look for

Returns:

a value of the given type found or null if none found.

findValueOfType

public static java.lang.Object findValueOfType(java.util.Collection<?> collection,
                                               java.lang.Class<?>[] types)

Find a single value of one of the given types in the given Collection: searching the Collection for a value of the first type, then searching for a value of the second type, etc.

Parameters:

collection - the collection to search

types - the types to look for, in prioritized order

Returns:

a value of one of the given types found if there is a clear match, or null if none or more than one such value found

hasUniqueObject

public static boolean hasUniqueObject(java.util.Collection collection)

Determine whether the given Collection only contains a single unique object.

Parameters:

collection - the Collection to check

Returns:

true if the collection contains a single reference or multiple references to the same instance, false else

findCommonElementType

public static java.lang.Class<?> findCommonElementType(java.util.Collection collection)

Find the common element type of the given Collection, if any.

Parameters:

collection - the Collection to check

Returns:

the common element type, or null if no clear common type has been found (or the collection was empty)

toArray

public static <A,E extends A> A[] toArray(java.util.Enumeration<E> enumeration,
                                                A[] array)

Marshal the elements from the given enumeration into an array of the given type. Enumeration elements must be assignable to the type of the given array. The array returned will be a different instance than the array given.

Type Parameters:

A - type of array

E - type of enumeration

Parameters:

enumeration - source enumeration

array - the array into which the elements of the list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.

Returns:

an array with the contents of the enumeration

toArray

public static <T> T[] toArray(java.util.Collection<T> c,
                              java.lang.Class<T> type)

toIterator

public static <E> java.util.Iterator<E> toIterator(java.util.Enumeration<E> enumeration)

Adapt an enumeration to an iterator.

Type Parameters:

E - type of enumeration

Parameters:

enumeration - the enumeration

Returns:

the iterator