org.springframework.core

Class CollectionFactory

java.lang.Object

org.springframework.core.CollectionFactory

public abstract class CollectionFactory
extends java.lang.Object

Factory for collections that is aware of Java 5, Java 6, and Spring collection types.

Mainly for internal use within the framework.

The goal of this class is to avoid runtime dependencies on a specific Java version, while nevertheless using the best collection implementation that is available at runtime.

Since:

1.1.1

Author:

Juergen Hoeller, Arjen Poutsma, Oliver Gierke, Sam Brannen

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.Set<java.lang.Class<?>>	approximableCollectionTypes
private static java.util.Set<java.lang.Class<?>>	approximableMapTypes

Constructor Summary

Constructors

Constructor and Description
CollectionFactory()

Method Summary

Modifier and Type	Method and Description
private static java.lang.Class<? extends java.lang.Enum>	asEnumType(java.lang.Class<?> enumType) Cast the given type to a subtype of Enum.
static <E> java.util.Collection<E>	createApproximateCollection(java.lang.Object collection, int capacity) Create the most approximate collection for the given collection.
static <K,V> java.util.Map<K,V>	createApproximateMap(java.lang.Object map, int capacity) Create the most approximate map for the given map.
static <E> java.util.Collection<E>	createCollection(java.lang.Class<?> collectionType, java.lang.Class<?> elementType, int capacity) Create the most appropriate collection for the given collection type.
static <E> java.util.Collection<E>	createCollection(java.lang.Class<?> collectionType, int capacity) Create the most appropriate collection for the given collection type.
static <K,V> java.util.Map<K,V>	createMap(java.lang.Class<?> mapType, java.lang.Class<?> keyType, int capacity) Create the most appropriate map for the given map type.
static <K,V> java.util.Map<K,V>	createMap(java.lang.Class<?> mapType, int capacity) Create the most appropriate map for the given map type.
static boolean	isApproximableCollectionType(java.lang.Class<?> collectionType) Determine whether the given collection type is an approximable type, i.e.
static boolean	isApproximableMapType(java.lang.Class<?> mapType) Determine whether the given map type is an approximable type, i.e.

Methods inherited from class java.lang.Object

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

Field Detail

approximableCollectionTypes

private static final java.util.Set<java.lang.Class<?>> approximableCollectionTypes

approximableMapTypes

private static final java.util.Set<java.lang.Class<?>> approximableMapTypes

Constructor Detail

CollectionFactory

public CollectionFactory()

Method Detail

isApproximableCollectionType

public static boolean isApproximableCollectionType(java.lang.Class<?> collectionType)

Determine whether the given collection type is an approximable type, i.e. a type that createApproximateCollection(java.lang.Object, int) can approximate.

Parameters:

collectionType - the collection type to check

Returns:

true if the type is approximable

createApproximateCollection

public static <E> java.util.Collection<E> createApproximateCollection(java.lang.Object collection,
                                                                      int capacity)

Create the most approximate collection for the given collection.

Warning: Since the parameterized type E is not bound to the type of elements contained in the supplied collection, type safety cannot be guaranteed if the supplied collection is an EnumSet. In such scenarios, the caller is responsible for ensuring that the element type for the supplied collection is an enum type matching type E. As an alternative, the caller may wish to treat the return value as a raw collection or collection of Object.

Parameters:

collection - the original collection object, potentially null

capacity - the initial capacity

Returns:

a new, empty collection instance

See Also:

isApproximableCollectionType(java.lang.Class<?>), LinkedList, ArrayList, EnumSet, TreeSet, LinkedHashSet

createCollection

public static <E> java.util.Collection<E> createCollection(java.lang.Class<?> collectionType,
                                                           int capacity)

Create the most appropriate collection for the given collection type.

Delegates to createCollection(Class, Class, int) with a null element type.

Parameters:

collectionType - the desired type of the target collection; never null

capacity - the initial capacity

Returns:

a new collection instance

Throws:

java.lang.IllegalArgumentException - if the supplied collectionType is null or of type EnumSet

createCollection

public static <E> java.util.Collection<E> createCollection(java.lang.Class<?> collectionType,
                                                           java.lang.Class<?> elementType,
                                                           int capacity)

Create the most appropriate collection for the given collection type.

Warning: Since the parameterized type E is not bound to the supplied elementType, type safety cannot be guaranteed if the desired collectionType is EnumSet. In such scenarios, the caller is responsible for ensuring that the supplied elementType is an enum type matching type E. As an alternative, the caller may wish to treat the return value as a raw collection or collection of Object.

Parameters:

collectionType - the desired type of the target collection; never null

elementType - the collection's element type, or null if unknown (note: only relevant for EnumSet creation)

capacity - the initial capacity

Returns:

a new collection instance

Throws:

java.lang.IllegalArgumentException - if the supplied collectionType is null; or if the desired collectionType is EnumSet and the supplied elementType is not a subtype of Enum

Since:

4.1.3

See Also:

LinkedHashSet, ArrayList, TreeSet, EnumSet

isApproximableMapType

public static boolean isApproximableMapType(java.lang.Class<?> mapType)

Determine whether the given map type is an approximable type, i.e. a type that createApproximateMap(java.lang.Object, int) can approximate.

Parameters:

mapType - the map type to check

Returns:

true if the type is approximable

createApproximateMap

public static <K,V> java.util.Map<K,V> createApproximateMap(java.lang.Object map,
                                                            int capacity)

Create the most approximate map for the given map.

Warning: Since the parameterized type K is not bound to the type of keys contained in the supplied map, type safety cannot be guaranteed if the supplied map is an EnumMap. In such scenarios, the caller is responsible for ensuring that the key type in the supplied map is an enum type matching type K. As an alternative, the caller may wish to treat the return value as a raw map or map keyed by Object.

Parameters:

map - the original map object, potentially null

capacity - the initial capacity

Returns:

a new, empty map instance

See Also:

isApproximableMapType(java.lang.Class<?>), EnumMap, TreeMap, LinkedHashMap

createMap

public static <K,V> java.util.Map<K,V> createMap(java.lang.Class<?> mapType,
                                                 int capacity)

Create the most appropriate map for the given map type.

Delegates to createMap(Class, Class, int) with a null key type.

Parameters:

mapType - the desired type of the target map

capacity - the initial capacity

Returns:

a new map instance

Throws:

java.lang.IllegalArgumentException - if the supplied mapType is null or of type EnumMap

createMap

public static <K,V> java.util.Map<K,V> createMap(java.lang.Class<?> mapType,
                                                 java.lang.Class<?> keyType,
                                                 int capacity)

Create the most appropriate map for the given map type.

Warning: Since the parameterized type K is not bound to the supplied keyType, type safety cannot be guaranteed if the desired mapType is EnumMap. In such scenarios, the caller is responsible for ensuring that the keyType is an enum type matching type K. As an alternative, the caller may wish to treat the return value as a raw map or map keyed by Object. Similarly, type safety cannot be enforced if the desired mapType is MultiValueMap.

Parameters:

mapType - the desired type of the target map; never null

keyType - the map's key type, or null if unknown (note: only relevant for EnumMap creation)

capacity - the initial capacity

Returns:

a new map instance

Throws:

java.lang.IllegalArgumentException - if the supplied mapType is null; or if the desired mapType is EnumMap and the supplied keyType is not a subtype of Enum

Since:

4.1.3

See Also:

LinkedHashMap, TreeMap, LinkedMultiValueMap, EnumMap

asEnumType

private static java.lang.Class<? extends java.lang.Enum> asEnumType(java.lang.Class<?> enumType)

Cast the given type to a subtype of Enum.

Parameters:

enumType - the enum type, never null

Returns:

the given type as subtype of Enum

Throws:

java.lang.IllegalArgumentException - if the given type is not a subtype of Enum