Package org.springframework.data.gemfire.util

Class CollectionUtils

java.lang.Object

org.springframework.util.CollectionUtils

org.springframework.data.gemfire.util.CollectionUtils

public abstract class CollectionUtils
extends CollectionUtils

CollectionUtils is an abstract utility class used to workin with the Java Collections Framework and classes.

Since:

1.7.0

Author:

John Blum

See Also:

• Collection
• Collections
• Enumeration
• Iterator
• List
• Map
• Set
• CollectionUtils

Constructor Summary

Constructors

Constructor	Description
CollectionUtils()

Method Summary

Modifier and Type	Method	Description
static <E, T extends Collection<E>> T	addAll(T collection, Iterable<E> iterable)	Adds all elements from the given Iterable to the Collection.
static <T> Set<T>	asSet(T... elements)	Returns an unmodifiable Set containing the elements from the given object array.
static boolean	containsAny(Collection<?> collection, Object... elements)	Null-safe method to determines whether the given Collection contains any elements from the given array.
static <T> Iterable<T>	emptyIterable()	Returns an empty Iterable object.
static <T> Iterable<T>	iterable(Enumeration<T> enumeration)	Adapts the given Enumeration as an Iterable object for use within a for each loop.
static <T> Iterable<T>	iterable(Iterator<T> iterator)	Adapts the given Iterator as an Iterable object for use within a for each loop.
static <T> Collection<T>	nullSafeCollection(Collection<T> collection)	Null-safe operation returning the given Collection if not null or an empty Collection (implemented with List) if null.
static <T> Enumeration<T>	nullSafeEnumeration(Enumeration<T> enumeration)	Null-safe operation returning the given Enumeration if not null or an empty Enumeration if null.
static boolean	nullSafeIsEmpty(Iterable<?> iterable)	Determines whether the given Iterable is empty.
static boolean	nullSafeIsEmpty(Collection<?> collection)	Determines whether the given Collection is empty.
static boolean	nullSafeIsEmpty(Map<?,?> map)	Determines whether the given Map is empty.
static <T> Iterable<T>	nullSafeIterable(Iterable<T> iterable)	A null-safe operation returning the original Iterable object if non-null or a default, empty Iterable implementation if null.
static <E, T extends Iterable<E>> T	nullSafeIterable(T iterable, T defaultIterable)	Returns the given Iterable if not null or empty, otherwise returns the defaultIterable.
static <T> Iterator<T>	nullSafeIterator(Iterator<T> iterator)	Null-safe operation returning the given Iterator if not null or an empty Iterator if null.
static <T> List<T>	nullSafeList(List<T> list)	Null-safe operation returning the given List if not null or an empty List if null.
static <K, V> Map<K,V>	nullSafeMap(Map<K,V> map)	Null-safe operation returning the given Map if not null or an empty Map if null.
static <T> Set<T>	nullSafeSet(Set<T> set)	Null-safe operation returning the given Set if not null or an empty Set if null.
static long	nullSafeSize(Iterable iterable)	Determines the size of the give Iterable.
static int	nullSafeSize(Collection<?> collection)	Determines the Collection.size() of the given Collection.
static int	nullSafeSize(Map<?,?> map)	Determines the Map.size() of the given Map.
static <T extends Comparable<T>> List<T>	sort(List<T> list)	Sors the elements of the given List by their natural, Comparable ordering.
static <T> List<T>	subList(List<T> source, int... indices)	Returns a sub-list of elements from the given List based on the provided indices.
static String	toString(Map<?,?> map)	Returns a String representation of the given Map.

Methods inherited from class org.springframework.util.CollectionUtils

arrayToList, contains, contains, containsAny, containsInstance, findCommonElementType, findFirstMatch, findValueOfType, findValueOfType, firstElement, firstElement, hasUniqueObject, isEmpty, isEmpty, lastElement, lastElement, mergeArrayIntoCollection, mergePropertiesIntoMap, newHashMap, newLinkedHashMap, toArray, toIterator, toMultiValueMap, unmodifiableMultiValueMap

Methods inherited from class java.lang.Object

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

Constructor Details

CollectionUtils

public CollectionUtils()

Method Details

addAll

public static <E,
T extends Collection<E>> T addAll(@NonNull
 T collection,
 @Nullable
 Iterable<E> iterable)

Adds all elements from the given Iterable to the Collection.

Type Parameters:

E - Class type of the elements in the Collection and Iterable.

T - concrete Class type of the Collection.

Parameters:

collection - Collection in which to add the elements from the Iterable.

iterable - Iterable containing the elements to add to the Collection.

Returns:

the given Collection.

Throws:

IllegalArgumentException - if Collection is null.

See Also:

• Iterable
• Collection

asSet

@SafeVarargs
public static <T> Set<T> asSet(@NonNull
 T... elements)

Returns an unmodifiable Set containing the elements from the given object array.

Type Parameters:

T - Class type of the elements.

Parameters:

elements - array of objects to add to the Set.

Returns:

an unmodifiable Set containing the elements from the given object array.

containsAny

public static boolean containsAny(@Nullable
 Collection<?> collection,
 @Nullable
 Object... elements)

Null-safe method to determines whether the given Collection contains any elements from the given array.

Parameters:

collection - Collection to evaluate

elements - array of elements to evaluate.

Returns:

a boolean value indicating whether the collection contains at least 1 element from the given array.

See Also:

• Collection.contains(Object)

emptyIterable

@NonNull
public static <T> Iterable<T> emptyIterable()

Returns an empty Iterable object.

Type Parameters:

T - Class type of the elements in the Iterable.

Returns:

an empty Iterable.

See Also:

• Iterable
• nullSafeIterable(Iterable)

iterable

@NonNull
public static <T> Iterable<T> iterable(@Nullable
 Enumeration<T> enumeration)

Adapts the given Enumeration as an Iterable object for use within a for each loop.

Type Parameters:

T - the class type of the Enumeration elements.

Parameters:

enumeration - the Enumeration to adapt as an Iterable object.

Returns:

an Iterable instance of the Enumeration.

See Also:

• Iterable
• Enumeration

iterable

@NonNull
public static <T> Iterable<T> iterable(@Nullable
 Iterator<T> iterator)

Adapts the given Iterator as an Iterable object for use within a for each loop.

Type Parameters:

T - the class type of the Iterator elements.

Parameters:

iterator - the Iterator to adapt as an Iterable object.

Returns:

an Iterable instance of the Iterator.

See Also:

• Iterable
• Iterator

nullSafeCollection

@NonNull
public static <T> Collection<T> nullSafeCollection(@Nullable
 Collection<T> collection)

Null-safe operation returning the given Collection if not null or an empty Collection (implemented with List) if null.

Type Parameters:

T - Class type of the Collection elements.

Parameters:

collection - Collection to evaluate.

Returns:

the given Collection if not null or return an empty Collection (implemented with List).

See Also:

• Collections.emptyList()
• Collection

nullSafeEnumeration

@NonNull
public static <T> Enumeration<T> nullSafeEnumeration(@Nullable
 Enumeration<T> enumeration)

Null-safe operation returning the given Enumeration if not null or an empty Enumeration if null.

Type Parameters:

T - type of elements contained in the Enumeration.

Parameters:

enumeration - Enumeration to evaluate.

Returns:

the given Enumeration if not null or an empty Enumeration.

See Also:

• Collections.emptyEnumeration()
• Enumeration

nullSafeIterable

@NonNull
public static <T> Iterable<T> nullSafeIterable(@Nullable
 Iterable<T> iterable)

A null-safe operation returning the original Iterable object if non-null or a default, empty Iterable implementation if null.

Type Parameters:

T - the class type of the iterable elements.

Parameters:

iterable - the Iterable object evaluated for a null reference.

Returns:

the Iterable object if not null or a default, empty Iterable implementation otherwise.

See Also:

• emptyIterable()
• Iterable

nullSafeIterable

@Nullable
public static <E,
T extends Iterable<E>> T nullSafeIterable(@Nullable
 T iterable,
 @Nullable
 T defaultIterable)

Returns the given Iterable if not null or empty, otherwise returns the defaultIterable.

Type Parameters:

T - concrete Class type of the Iterable.

E - Class type of the elements in the Iterables.

Parameters:

iterable - Iterable to evaluate.

defaultIterable - Iterable to return if the given iterable is null or empty.

Returns:

iterable if not null or empty otherwise return defaultIterable.

See Also:

• Iterable

nullSafeIterator

@NonNull
public static <T> Iterator<T> nullSafeIterator(@Nullable
 Iterator<T> iterator)

Null-safe operation returning the given Iterator if not null or an empty Iterator if null.

Type Parameters:

T - type of elements contained in the Iterator.

Parameters:

iterator - Iterator to evaluate.

Returns:

the given Iterator if not null or an empty Iterator.

See Also:

• Collections.emptyIterator()
• Iterator

nullSafeList

@NonNull
public static <T> List<T> nullSafeList(@Nullable
 List<T> list)

Null-safe operation returning the given List if not null or an empty List if null.

Type Parameters:

T - Class type of the List elements.

Parameters:

list - List to evaluate.

Returns:

the given List if not null or an empty List.

See Also:

• Collections.emptyList()
• List

nullSafeMap

@NonNull
public static <K,
V> Map<K,V> nullSafeMap(@Nullable
 Map<K,V> map)

Null-safe operation returning the given Map if not null or an empty Map if null.

Type Parameters:

K - Class type of the Map's keys.

V - Class type of the Map's values.

Parameters:

map - Map to evaluate.

Returns:

the given Map if not null or an empty Map.

See Also:

• Collections.emptyMap()
• Map

nullSafeSet

@NonNull
public static <T> Set<T> nullSafeSet(@Nullable
 Set<T> set)

Null-safe operation returning the given Set if not null or an empty Set if null.

Type Parameters:

T - Class type of the Set elements.

Parameters:

set - Set to evaluate.

Returns:

the given Set if not null or an empty Set.

See Also:

• Collections.emptySet()
• Set

nullSafeIsEmpty

public static boolean nullSafeIsEmpty(@Nullable
 Collection<?> collection)

Determines whether the given Collection is empty.

Parameters:

collection - Collection to evaluate.

Returns:

a boolean value indicating whether the given Collection is empty.

See Also:

• nullSafeCollection(Collection)
• Collection.isEmpty()

nullSafeIsEmpty

public static boolean nullSafeIsEmpty(@Nullable
 Iterable<?> iterable)

Determines whether the given Iterable is empty.

Parameters:

iterable - Iterable to evaluate.

Returns:

a boolean value indicating whether the given Iterable is empty.

See Also:

• Iterable
• nullSafeIterable(Iterable)

nullSafeIsEmpty

public static boolean nullSafeIsEmpty(@Nullable
 Map<?,?> map)

Determines whether the given Map is empty.

Parameters:

map - Map to evaluate.

Returns:

a boolean value indicating whether the given Map is empty.

See Also:

• nullSafeMap(Map)
• Map.isEmpty()

nullSafeSize

public static int nullSafeSize(@Nullable
 Collection<?> collection)

Determines the Collection.size() of the given Collection.

Parameters:

collection - Collection to evaluate.

Returns:

the Collection.size() of the given Collection.

See Also:

• nullSafeCollection(Collection)
• Collection.size()

nullSafeSize

public static long nullSafeSize(@Nullable
 Iterable iterable)

Determines the size of the give Iterable.

Parameters:

iterable - Iterable to evaluate.

Returns:

the size indicating the number of elements contained by the given Iterable. If Iterable is null, then returns 0.

See Also:

• Iterable

nullSafeSize

public static int nullSafeSize(@Nullable
 Map<?,?> map)

Determines the Map.size() of the given Map.

Parameters:

map - Map to evaluate.

Returns:

the Map.size() of the given Map.

See Also:

• nullSafeMap(Map)
• Map.size()

sort

public static <T extends Comparable<T>> List<T> sort(@NonNull
 List<T> list)

Sors the elements of the given List by their natural, Comparable ordering.

Type Parameters:

T - Comparable class type of the collection elements.

Parameters:

list - List of elements to sort.

Returns:

the List sorted.

See Also:

• Collections.sort(List)
• List

subList

public static <T> List<T> subList(@NonNull
 List<T> source,
 int... indices)

Returns a sub-list of elements from the given List based on the provided indices.

Type Parameters:

T - Class type of the elements in the list.

Parameters:

source - List from which the elements of the sub-list is constructed.

indices - array of indexes in the source List to the elements used to construct the sub-list.

Returns:

a sub-list of elements from the given List based on the provided indices.

Throws:

IndexOutOfBoundsException - if the array of indexes contains an index that is not within the bounds of the list.

NullPointerException - if either the list or indexes are null.

See Also:

• List

toString

@NonNull
public static String toString(@Nullable
 Map<?,?> map)

Returns a String representation of the given Map.

Parameters:

map - Map represent as a String.

Returns:

a String describing the given Map.

See Also:

• newSortedMap(Map)
• Map