com.springsource.util.common
Class CollectionUtils

java.lang.Object
  com.springsource.util.common.CollectionUtils

public abstract class CollectionUtils
extends java.lang.Object

Miscellaneous collection utility methods.

Author:

Juergen Hoeller, Rob Harrop

Constructor Summary

CollectionUtils()

Method Summary

static <T> java.util.List<T>	arrayToList(T[] 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.Object	findFirstMatch(java.util.Collection<?> source, java.util.Collection<?> candidates) Return the first element in 'candidates' that is contained in 'source'.
static java.lang.Object	findValueOfType(java.util.Collection<?> collection, java.lang.Class<?> type) Find a single value of the given type in the given Collection.
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 <T> void	mergeArrayIntoCollection(T[] array, java.util.Collection<T> collection) Merge the given array into the given Collection.
static void	mergePropertiesIntoMap(java.util.Properties props, java.util.Map<? super java.lang.String,? super java.lang.String> map) Merge the given Properties instance into the given Map, copying all properties (key-value pairs) over.

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

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

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 <T> java.util.List<T> arrayToList(T[] source)

Convert the supplied array into a List.

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

Type Parameters:

T - the type of elements of the list

Parameters:

source - the array

Returns:

the converted List result

See Also:

ObjectUtils.toObjectArray(Object)

mergeArrayIntoCollection

public static <T> void mergeArrayIntoCollection(T[] array,
                                                java.util.Collection<T> collection)

Merge the given array into the given Collection.

Type Parameters:

T - type of elements of array

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<? super java.lang.String,? super java.lang.String> 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

findValueOfType

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

Find a single value of the given type in the given Collection.

Parameters:

collection - the Collection to search

type - the type to look for

Returns:

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