org.apache.commons.collections4

Class MapUtils

java.lang.Object

org.apache.commons.collections4.MapUtils

public class MapUtils
extends java.lang.Object

Provides utility methods and decorators for Map and SortedMap instances.

It contains various type safe methods as well as other useful features like deep copying.

It also provides the following decorators:

• fixedSizeMap(Map)
• fixedSizeSortedMap(SortedMap)
• lazyMap(Map,Factory)
• lazyMap(Map,Transformer)
• lazySortedMap(SortedMap,Factory)
• lazySortedMap(SortedMap,Transformer)
• predicatedMap(Map,Predicate,Predicate)
• predicatedSortedMap(SortedMap,Predicate,Predicate)
• transformedMap(Map, Transformer, Transformer)
• transformedSortedMap(SortedMap, Transformer, Transformer)
• multiValueMap( Map )
• multiValueMap( Map, Class )
• multiValueMap( Map, Factory )

Since:

1.0

Field Summary

Fields

Modifier and Type	Field and Description
static java.util.SortedMap	EMPTY_SORTED_MAP An empty unmodifiable sorted map.

Method Summary

Modifier and Type	Method and Description
static void	debugPrint(java.io.PrintStream out, java.lang.Object label, java.util.Map<?,?> map) Prints the given map with nice line breaks.
static <K,V> java.util.Map<K,V>	emptyIfNull(java.util.Map<K,V> map) Returns an immutable empty map if the argument is null, or the argument itself otherwise.
static <K,V> IterableMap<K,V>	fixedSizeMap(java.util.Map<K,V> map) Returns a fixed-sized map backed by the given map.
static <K,V> java.util.SortedMap<K,V>	fixedSizeSortedMap(java.util.SortedMap<K,V> map) Returns a fixed-sized sorted map backed by the given sorted map.
static <K> java.lang.Boolean	getBoolean(java.util.Map<? super K,?> map, K key) Gets a Boolean from a Map in a null-safe manner.
static <K> java.lang.Boolean	getBoolean(java.util.Map<? super K,?> map, K key, java.lang.Boolean defaultValue) Looks up the given key in the given map, converting the result into a boolean, using the default value if the the conversion fails.
static <K> boolean	getBooleanValue(java.util.Map<? super K,?> map, K key) Gets a boolean from a Map in a null-safe manner.
static <K> boolean	getBooleanValue(java.util.Map<? super K,?> map, K key, boolean defaultValue) Gets a boolean from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.Byte	getByte(java.util.Map<? super K,?> map, K key) Gets a Byte from a Map in a null-safe manner.
static <K> java.lang.Byte	getByte(java.util.Map<? super K,?> map, K key, java.lang.Byte defaultValue) Looks up the given key in the given map, converting the result into a byte, using the default value if the the conversion fails.
static <K> byte	getByteValue(java.util.Map<? super K,?> map, K key) Gets a byte from a Map in a null-safe manner.
static <K> byte	getByteValue(java.util.Map<? super K,?> map, K key, byte defaultValue) Gets a byte from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.Double	getDouble(java.util.Map<? super K,?> map, K key) Gets a Double from a Map in a null-safe manner.
static <K> java.lang.Double	getDouble(java.util.Map<? super K,?> map, K key, java.lang.Double defaultValue) Looks up the given key in the given map, converting the result into a double, using the default value if the the conversion fails.
static <K> double	getDoubleValue(java.util.Map<? super K,?> map, K key) Gets a double from a Map in a null-safe manner.
static <K> double	getDoubleValue(java.util.Map<? super K,?> map, K key, double defaultValue) Gets a double from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.Float	getFloat(java.util.Map<? super K,?> map, K key) Gets a Float from a Map in a null-safe manner.
static <K> java.lang.Float	getFloat(java.util.Map<? super K,?> map, K key, java.lang.Float defaultValue) Looks up the given key in the given map, converting the result into a float, using the default value if the the conversion fails.
static <K> float	getFloatValue(java.util.Map<? super K,?> map, K key) Gets a float from a Map in a null-safe manner.
static <K> float	getFloatValue(java.util.Map<? super K,?> map, K key, float defaultValue) Gets a float from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.Integer	getInteger(java.util.Map<? super K,?> map, K key) Gets a Integer from a Map in a null-safe manner.
static <K> java.lang.Integer	getInteger(java.util.Map<? super K,?> map, K key, java.lang.Integer defaultValue) Looks up the given key in the given map, converting the result into an integer, using the default value if the the conversion fails.
static <K> int	getIntValue(java.util.Map<? super K,?> map, K key) Gets an int from a Map in a null-safe manner.
static <K> int	getIntValue(java.util.Map<? super K,?> map, K key, int defaultValue) Gets an int from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.Long	getLong(java.util.Map<? super K,?> map, K key) Gets a Long from a Map in a null-safe manner.
static <K> java.lang.Long	getLong(java.util.Map<? super K,?> map, K key, java.lang.Long defaultValue) Looks up the given key in the given map, converting the result into a long, using the default value if the the conversion fails.
static <K> long	getLongValue(java.util.Map<? super K,?> map, K key) Gets a long from a Map in a null-safe manner.
static <K> long	getLongValue(java.util.Map<? super K,?> map, K key, long defaultValue) Gets a long from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.util.Map<?,?>	getMap(java.util.Map<? super K,?> map, K key) Gets a Map from a Map in a null-safe manner.
static <K> java.util.Map<?,?>	getMap(java.util.Map<? super K,?> map, K key, java.util.Map<?,?> defaultValue) Looks up the given key in the given map, converting the result into a map, using the default value if the the conversion fails.
static <K> java.lang.Number	getNumber(java.util.Map<? super K,?> map, K key) Gets a Number from a Map in a null-safe manner.
static <K> java.lang.Number	getNumber(java.util.Map<? super K,?> map, K key, java.lang.Number defaultValue) Looks up the given key in the given map, converting the result into a number, using the default value if the the conversion fails.
static <K,V> V	getObject(java.util.Map<? super K,V> map, K key) Gets from a Map in a null-safe manner.
static <K,V> V	getObject(java.util.Map<K,V> map, K key, V defaultValue) Looks up the given key in the given map, converting null into the given default value.
static <K> java.lang.Short	getShort(java.util.Map<? super K,?> map, K key) Gets a Short from a Map in a null-safe manner.
static <K> java.lang.Short	getShort(java.util.Map<? super K,?> map, K key, java.lang.Short defaultValue) Looks up the given key in the given map, converting the result into a short, using the default value if the the conversion fails.
static <K> short	getShortValue(java.util.Map<? super K,?> map, K key) Gets a short from a Map in a null-safe manner.
static <K> short	getShortValue(java.util.Map<? super K,?> map, K key, short defaultValue) Gets a short from a Map in a null-safe manner, using the default value if the the conversion fails.
static <K> java.lang.String	getString(java.util.Map<? super K,?> map, K key) Gets a String from a Map in a null-safe manner.
static <K> java.lang.String	getString(java.util.Map<? super K,?> map, K key, java.lang.String defaultValue) Looks up the given key in the given map, converting the result into a string, using the default value if the the conversion fails.
static <K,V> java.util.Map<V,K>	invertMap(java.util.Map<K,V> map) Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values.
static boolean	isEmpty(java.util.Map<?,?> map) Null-safe check if the specified map is empty.
static boolean	isNotEmpty(java.util.Map<?,?> map) Null-safe check if the specified map is not empty.
static <K,V> IterableMap<K,V>	iterableMap(java.util.Map<K,V> map) Get the specified Map as an IterableMap.
static <K,V> IterableSortedMap<K,V>	iterableSortedMap(java.util.SortedMap<K,V> sortedMap) Get the specified SortedMap as an IterableSortedMap.
static <K,V> IterableMap<K,V>	lazyMap(java.util.Map<K,V> map, Factory<? extends V> factory) Returns a "lazy" map whose values will be created on demand.
static <K,V> IterableMap<K,V>	lazyMap(java.util.Map<K,V> map, Transformer<? super K,? extends V> transformerFactory) Returns a "lazy" map whose values will be created on demand.
static <K,V> java.util.SortedMap<K,V>	lazySortedMap(java.util.SortedMap<K,V> map, Factory<? extends V> factory) Returns a "lazy" sorted map whose values will be created on demand.
static <K,V> java.util.SortedMap<K,V>	lazySortedMap(java.util.SortedMap<K,V> map, Transformer<? super K,? extends V> transformerFactory) Returns a "lazy" sorted map whose values will be created on demand.
static <K,V> MultiValueMap<K,V>	multiValueMap(java.util.Map<K,? super java.util.Collection<V>> map) Deprecated. since 4.1, use MultiValuedMap instead
static <K,V,C extends java.util.Collection<V>> MultiValueMap<K,V>	multiValueMap(java.util.Map<K,C> map, java.lang.Class<C> collectionClass) Deprecated. since 4.1, use MultiValuedMap instead
static <K,V,C extends java.util.Collection<V>> MultiValueMap<K,V>	multiValueMap(java.util.Map<K,C> map, Factory<C> collectionFactory) Deprecated. since 4.1, use MultiValuedMap instead
static <K,V> OrderedMap<K,V>	orderedMap(java.util.Map<K,V> map) Returns a map that maintains the order of keys that are added backed by the given map.
static <K,V,E> void	populateMap(java.util.Map<K,V> map, java.lang.Iterable<? extends E> elements, Transformer<E,K> keyTransformer, Transformer<E,V> valueTransformer) Populates a Map using the supplied Transformers to transform the elements into keys and values.
static <K,V> void	populateMap(java.util.Map<K,V> map, java.lang.Iterable<? extends V> elements, Transformer<V,K> keyTransformer) Populates a Map using the supplied Transformer to transform the elements into keys, using the unaltered element as the value in the Map.
static <K,V,E> void	populateMap(MultiMap<K,V> map, java.lang.Iterable<? extends E> elements, Transformer<E,K> keyTransformer, Transformer<E,V> valueTransformer) Populates a MultiMap using the supplied Transformers to transform the elements into keys and values.
static <K,V> void	populateMap(MultiMap<K,V> map, java.lang.Iterable<? extends V> elements, Transformer<V,K> keyTransformer) Populates a MultiMap using the supplied Transformer to transform the elements into keys, using the unaltered element as the value in the MultiMap.
static <K,V> IterableMap<K,V>	predicatedMap(java.util.Map<K,V> map, Predicate<? super K> keyPred, Predicate<? super V> valuePred) Returns a predicated (validating) map backed by the given map.
static <K,V> java.util.SortedMap<K,V>	predicatedSortedMap(java.util.SortedMap<K,V> map, Predicate<? super K> keyPred, Predicate<? super V> valuePred) Returns a predicated (validating) sorted map backed by the given map.
static <K,V> java.util.Map<K,V>	putAll(java.util.Map<K,V> map, java.lang.Object[] array) Puts all the keys and values from the specified array into the map.
static <K> void	safeAddToMap(java.util.Map<? super K,java.lang.Object> map, K key, java.lang.Object value) Protects against adding null values to a map.
static <K,V> java.util.Map<K,V>	synchronizedMap(java.util.Map<K,V> map) Returns a synchronized map backed by the given map.
static <K,V> java.util.SortedMap<K,V>	synchronizedSortedMap(java.util.SortedMap<K,V> map) Returns a synchronized sorted map backed by the given sorted map.
static java.util.Map<java.lang.String,java.lang.Object>	toMap(java.util.ResourceBundle resourceBundle) Creates a new HashMap using data copied from a ResourceBundle.
static <K,V> java.util.Properties	toProperties(java.util.Map<K,V> map) Gets a new Properties object initialised with the values from a Map.
static <K,V> IterableMap<K,V>	transformedMap(java.util.Map<K,V> map, Transformer<? super K,? extends K> keyTransformer, Transformer<? super V,? extends V> valueTransformer) Returns a transformed map backed by the given map.
static <K,V> java.util.SortedMap<K,V>	transformedSortedMap(java.util.SortedMap<K,V> map, Transformer<? super K,? extends K> keyTransformer, Transformer<? super V,? extends V> valueTransformer) Returns a transformed sorted map backed by the given map.
static <K,V> java.util.Map<K,V>	unmodifiableMap(java.util.Map<? extends K,? extends V> map) Returns an unmodifiable map backed by the given map.
static <K,V> java.util.SortedMap<K,V>	unmodifiableSortedMap(java.util.SortedMap<K,? extends V> map) Returns an unmodifiable sorted map backed by the given sorted map.
static void	verbosePrint(java.io.PrintStream out, java.lang.Object label, java.util.Map<?,?> map) Prints the given map with nice line breaks.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_SORTED_MAP

public static final java.util.SortedMap EMPTY_SORTED_MAP

An empty unmodifiable sorted map. This is not provided in the JDK.

Method Detail

getObject

public static <K,V> V getObject(java.util.Map<? super K,V> map,
                                K key)

Gets from a Map in a null-safe manner.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map, null if null map input

getString

public static <K> java.lang.String getString(java.util.Map<? super K,?> map,
                                             K key)

Gets a String from a Map in a null-safe manner.

The String is obtained via toString.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a String, null if null map input

getBoolean

public static <K> java.lang.Boolean getBoolean(java.util.Map<? super K,?> map,
                                               K key)

Gets a Boolean from a Map in a null-safe manner.

If the value is a Boolean it is returned directly. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, null is returned.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Boolean, null if null map input

getNumber

public static <K> java.lang.Number getNumber(java.util.Map<? super K,?> map,
                                             K key)

Gets a Number from a Map in a null-safe manner.

If the value is a Number it is returned directly. If the value is a String it is converted using NumberFormat.parse(String) on the system default formatter returning null if the conversion fails. Otherwise, null is returned.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Number, null if null map input

getByte

public static <K> java.lang.Byte getByte(java.util.Map<? super K,?> map,
                                         K key)

Gets a Byte from a Map in a null-safe manner.

The Byte is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Byte, null if null map input

getShort

public static <K> java.lang.Short getShort(java.util.Map<? super K,?> map,
                                           K key)

Gets a Short from a Map in a null-safe manner.

The Short is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Short, null if null map input

getInteger

public static <K> java.lang.Integer getInteger(java.util.Map<? super K,?> map,
                                               K key)

Gets a Integer from a Map in a null-safe manner.

The Integer is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Integer, null if null map input

getLong

public static <K> java.lang.Long getLong(java.util.Map<? super K,?> map,
                                         K key)

Gets a Long from a Map in a null-safe manner.

The Long is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Long, null if null map input

getFloat

public static <K> java.lang.Float getFloat(java.util.Map<? super K,?> map,
                                           K key)

Gets a Float from a Map in a null-safe manner.

The Float is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Float, null if null map input

getDouble

public static <K> java.lang.Double getDouble(java.util.Map<? super K,?> map,
                                             K key)

Gets a Double from a Map in a null-safe manner.

The Double is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Double, null if null map input

getMap

public static <K> java.util.Map<?,?> getMap(java.util.Map<? super K,?> map,
                                            K key)

Gets a Map from a Map in a null-safe manner.

If the value returned from the specified map is not a Map then null is returned.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Map, null if null map input

getObject

public static <K,V> V getObject(java.util.Map<K,V> map,
                                K key,
                                V defaultValue)

Looks up the given key in the given map, converting null into the given default value.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null

Returns:

the value in the map, or defaultValue if the original value is null or the map is null

getString

public static <K> java.lang.String getString(java.util.Map<? super K,?> map,
                                             K key,
                                             java.lang.String defaultValue)

Looks up the given key in the given map, converting the result into a string, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a string, or defaultValue if the original value is null, the map is null or the string conversion fails

getBoolean

public static <K> java.lang.Boolean getBoolean(java.util.Map<? super K,?> map,
                                               K key,
                                               java.lang.Boolean defaultValue)

Looks up the given key in the given map, converting the result into a boolean, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a boolean, or defaultValue if the original value is null, the map is null or the boolean conversion fails

getNumber

public static <K> java.lang.Number getNumber(java.util.Map<? super K,?> map,
                                             K key,
                                             java.lang.Number defaultValue)

Looks up the given key in the given map, converting the result into a number, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getByte

public static <K> java.lang.Byte getByte(java.util.Map<? super K,?> map,
                                         K key,
                                         java.lang.Byte defaultValue)

Looks up the given key in the given map, converting the result into a byte, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getShort

public static <K> java.lang.Short getShort(java.util.Map<? super K,?> map,
                                           K key,
                                           java.lang.Short defaultValue)

Looks up the given key in the given map, converting the result into a short, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getInteger

public static <K> java.lang.Integer getInteger(java.util.Map<? super K,?> map,
                                               K key,
                                               java.lang.Integer defaultValue)

Looks up the given key in the given map, converting the result into an integer, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getLong

public static <K> java.lang.Long getLong(java.util.Map<? super K,?> map,
                                         K key,
                                         java.lang.Long defaultValue)

Looks up the given key in the given map, converting the result into a long, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getFloat

public static <K> java.lang.Float getFloat(java.util.Map<? super K,?> map,
                                           K key,
                                           java.lang.Float defaultValue)

Looks up the given key in the given map, converting the result into a float, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getDouble

public static <K> java.lang.Double getDouble(java.util.Map<? super K,?> map,
                                             K key,
                                             java.lang.Double defaultValue)

Looks up the given key in the given map, converting the result into a double, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the number conversion fails

getMap

public static <K> java.util.Map<?,?> getMap(java.util.Map<? super K,?> map,
                                            K key,
                                            java.util.Map<?,?> defaultValue)

Looks up the given key in the given map, converting the result into a map, using the default value if the the conversion fails.

Type Parameters:

K - the key type

Parameters:

map - the map whose value to look up

key - the key of the value to look up in that map

defaultValue - what to return if the value is null or if the conversion fails

Returns:

the value in the map as a number, or defaultValue if the original value is null, the map is null or the map conversion fails

getBooleanValue

public static <K> boolean getBooleanValue(java.util.Map<? super K,?> map,
                                          K key)

Gets a boolean from a Map in a null-safe manner.

If the value is a Boolean its value is returned. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, false is returned.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a Boolean, false if null map input

getByteValue

public static <K> byte getByteValue(java.util.Map<? super K,?> map,
                                    K key)

Gets a byte from a Map in a null-safe manner.

The byte is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a byte, 0 if null map input

getShortValue

public static <K> short getShortValue(java.util.Map<? super K,?> map,
                                      K key)

Gets a short from a Map in a null-safe manner.

The short is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a short, 0 if null map input

getIntValue

public static <K> int getIntValue(java.util.Map<? super K,?> map,
                                  K key)

Gets an int from a Map in a null-safe manner.

The int is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as an int, 0 if null map input

getLongValue

public static <K> long getLongValue(java.util.Map<? super K,?> map,
                                    K key)

Gets a long from a Map in a null-safe manner.

The long is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a long, 0L if null map input

getFloatValue

public static <K> float getFloatValue(java.util.Map<? super K,?> map,
                                      K key)

Gets a float from a Map in a null-safe manner.

The float is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a float, 0.0F if null map input

getDoubleValue

public static <K> double getDoubleValue(java.util.Map<? super K,?> map,
                                        K key)

Gets a double from a Map in a null-safe manner.

The double is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

Returns:

the value in the Map as a double, 0.0 if null map input

getBooleanValue

public static <K> boolean getBooleanValue(java.util.Map<? super K,?> map,
                                          K key,
                                          boolean defaultValue)

Gets a boolean from a Map in a null-safe manner, using the default value if the the conversion fails.

If the value is a Boolean its value is returned. If the value is a String and it equals 'true' ignoring case then true is returned, otherwise false. If the value is a Number an integer zero value returns false and non-zero returns true. Otherwise, defaultValue is returned.

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a Boolean, defaultValue if null map input

getByteValue

public static <K> byte getByteValue(java.util.Map<? super K,?> map,
                                    K key,
                                    byte defaultValue)

Gets a byte from a Map in a null-safe manner, using the default value if the the conversion fails.

The byte is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a byte, defaultValue if null map input

getShortValue

public static <K> short getShortValue(java.util.Map<? super K,?> map,
                                      K key,
                                      short defaultValue)

Gets a short from a Map in a null-safe manner, using the default value if the the conversion fails.

The short is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a short, defaultValue if null map input

getIntValue

public static <K> int getIntValue(java.util.Map<? super K,?> map,
                                  K key,
                                  int defaultValue)

Gets an int from a Map in a null-safe manner, using the default value if the the conversion fails.

The int is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as an int, defaultValue if null map input

getLongValue

public static <K> long getLongValue(java.util.Map<? super K,?> map,
                                    K key,
                                    long defaultValue)

Gets a long from a Map in a null-safe manner, using the default value if the the conversion fails.

The long is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a long, defaultValue if null map input

getFloatValue

public static <K> float getFloatValue(java.util.Map<? super K,?> map,
                                      K key,
                                      float defaultValue)

Gets a float from a Map in a null-safe manner, using the default value if the the conversion fails.

The float is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a float, defaultValue if null map input

getDoubleValue

public static <K> double getDoubleValue(java.util.Map<? super K,?> map,
                                        K key,
                                        double defaultValue)

Gets a double from a Map in a null-safe manner, using the default value if the the conversion fails.

The double is obtained from the results of getNumber(Map,Object).

Type Parameters:

K - the key type

Parameters:

map - the map to use

key - the key to look up

defaultValue - return if the value is null or if the conversion fails

Returns:

the value in the Map as a double, defaultValue if null map input

toProperties

public static <K,V> java.util.Properties toProperties(java.util.Map<K,V> map)

Gets a new Properties object initialised with the values from a Map. A null input will return an empty properties object.

A Properties object may only store non-null keys and values, thus if the provided map contains either a key or value which is null, a NullPointerException will be thrown.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to convert to a Properties object

Returns:

the properties object

Throws:

java.lang.NullPointerException - if a key or value in the provided map is null

toMap

public static java.util.Map<java.lang.String,java.lang.Object> toMap(java.util.ResourceBundle resourceBundle)

Creates a new HashMap using data copied from a ResourceBundle.

Parameters:

resourceBundle - the resource bundle to convert, may not be null

Returns:

the hashmap containing the data

Throws:

java.lang.NullPointerException - if the bundle is null

verbosePrint

public static void verbosePrint(java.io.PrintStream out,
                                java.lang.Object label,
                                java.util.Map<?,?> map)

Prints the given map with nice line breaks.

This method prints a nicely formatted String describing the Map. Each map entry will be printed with key and value. When the value is a Map, recursive behaviour occurs.

This method is NOT thread-safe in any special way. You must manually synchronize on either this class or the stream as required.

Parameters:

out - the stream to print to, must not be null

label - The label to be used, may be null. If null, the label is not output. It typically represents the name of the property in a bean or similar.

map - The map to print, may be null. If null, the text 'null' is output.

Throws:

java.lang.NullPointerException - if the stream is null

debugPrint

public static void debugPrint(java.io.PrintStream out,
                              java.lang.Object label,
                              java.util.Map<?,?> map)

Prints the given map with nice line breaks.

This method prints a nicely formatted String describing the Map. Each map entry will be printed with key, value and value classname. When the value is a Map, recursive behaviour occurs.

This method is NOT thread-safe in any special way. You must manually synchronize on either this class or the stream as required.

Parameters:

out - the stream to print to, must not be null

label - The label to be used, may be null. If null, the label is not output. It typically represents the name of the property in a bean or similar.

map - The map to print, may be null. If null, the text 'null' is output.

Throws:

java.lang.NullPointerException - if the stream is null

invertMap

public static <K,V> java.util.Map<V,K> invertMap(java.util.Map<K,V> map)

Inverts the supplied map returning a new HashMap such that the keys of the input are swapped with the values.

This operation assumes that the inverse mapping is well defined. If the input map had multiple entries with the same value mapped to different keys, the returned map will map one of those keys to the value, but the exact key which will be mapped is undefined.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to invert, may not be null

Returns:

a new HashMap containing the inverted data

Throws:

java.lang.NullPointerException - if the map is null

safeAddToMap

public static <K> void safeAddToMap(java.util.Map<? super K,java.lang.Object> map,
                                    K key,
                                    java.lang.Object value)
                             throws java.lang.NullPointerException

Protects against adding null values to a map.

This method checks the value being added to the map, and if it is null it is replaced by an empty string.

This could be useful if the map does not accept null values, or for receiving data from a source that may provide null or empty string which should be held in the same way in the map.

Keys are not validated. Note that this method can be used to circumvent the map's value type at runtime.

Type Parameters:

K - the key type

Parameters:

map - the map to add to, may not be null

key - the key

value - the value, null converted to ""

Throws:

java.lang.NullPointerException - if the map is null

putAll

public static <K,V> java.util.Map<K,V> putAll(java.util.Map<K,V> map,
                                              java.lang.Object[] array)

Puts all the keys and values from the specified array into the map.

This method is an alternative to the Map.putAll(java.util.Map) method and constructors. It allows you to build a map from an object array of various possible styles.

If the first entry in the object array implements Map.Entry or KeyValue then the key and value are added from that object. If the first entry in the object array is an object array itself, then it is assumed that index 0 in the sub-array is the key and index 1 is the value. Otherwise, the array is treated as keys and values in alternate indices.

For example, to create a color map:

 Map colorMap = MapUtils.putAll(new HashMap(), new String[][] {
     {"RED", "#FF0000"},
     {"GREEN", "#00FF00"},
     {"BLUE", "#0000FF"}
 });
 

or:

 Map colorMap = MapUtils.putAll(new HashMap(), new String[] {
     "RED", "#FF0000",
     "GREEN", "#00FF00",
     "BLUE", "#0000FF"
 });
 

or:

 Map colorMap = MapUtils.putAll(new HashMap(), new Map.Entry[] {
     new DefaultMapEntry("RED", "#FF0000"),
     new DefaultMapEntry("GREEN", "#00FF00"),
     new DefaultMapEntry("BLUE", "#0000FF")
 });
 

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to populate, must not be null

array - an array to populate from, null ignored

Returns:

the input map

Throws:

java.lang.NullPointerException - if map is null

java.lang.IllegalArgumentException - if sub-array or entry matching used and an entry is invalid

java.lang.ClassCastException - if the array contents is mixed

Since:

3.2

emptyIfNull

public static <K,V> java.util.Map<K,V> emptyIfNull(java.util.Map<K,V> map)

Returns an immutable empty map if the argument is null, or the argument itself otherwise.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map, possibly null

Returns:

an empty map if the argument is null

isEmpty

public static boolean isEmpty(java.util.Map<?,?> map)

Null-safe check if the specified map is empty.

Null returns true.

Parameters:

map - the map to check, may be null

Returns:

true if empty or null

Since:

3.2

isNotEmpty

public static boolean isNotEmpty(java.util.Map<?,?> map)

Null-safe check if the specified map is not empty.

Null returns false.

Parameters:

map - the map to check, may be null

Returns:

true if non-null and non-empty

Since:

3.2

synchronizedMap

public static <K,V> java.util.Map<K,V> synchronizedMap(java.util.Map<K,V> map)

Returns a synchronized map backed by the given map.

You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:

 Map m = MapUtils.synchronizedMap(myMap);
 Set s = m.keySet();  // outside synchronized block
 synchronized (m) {  // synchronized on MAP!
     Iterator i = s.iterator();
     while (i.hasNext()) {
         process (i.next());
     }
 }
 

This method uses the implementation in Collections.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to synchronize, must not be null

Returns:

a synchronized map backed by the given map

unmodifiableMap

public static <K,V> java.util.Map<K,V> unmodifiableMap(java.util.Map<? extends K,? extends V> map)

Returns an unmodifiable map backed by the given map.

This method uses the implementation in the decorators subpackage.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to make unmodifiable, must not be null

Returns:

an unmodifiable map backed by the given map

Throws:

java.lang.NullPointerException - if the map is null

predicatedMap

public static <K,V> IterableMap<K,V> predicatedMap(java.util.Map<K,V> map,
                                                   Predicate<? super K> keyPred,
                                                   Predicate<? super V> valuePred)

Returns a predicated (validating) map backed by the given map.

Only objects that pass the tests in the given predicates can be added to the map. Trying to add an invalid object results in an IllegalArgumentException. Keys must pass the key predicate, values must pass the value predicate. It is important not to use the original map after invoking this method, as it is a backdoor for adding invalid objects.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to predicate, must not be null

keyPred - the predicate for keys, null means no check

valuePred - the predicate for values, null means no check

Returns:

a predicated map backed by the given map

Throws:

java.lang.NullPointerException - if the Map is null

transformedMap

public static <K,V> IterableMap<K,V> transformedMap(java.util.Map<K,V> map,
                                                    Transformer<? super K,? extends K> keyTransformer,
                                                    Transformer<? super V,? extends V> valueTransformer)

Returns a transformed map backed by the given map.

This method returns a new map (decorating the specified map) that will transform any new entries added to it. Existing entries in the specified map will not be transformed. If you want that behaviour, see TransformedMap.transformedMap(java.util.Map<K, V>, org.apache.commons.collections4.Transformer<? super K, ? extends K>, org.apache.commons.collections4.Transformer<? super V, ? extends V>).

Each object is passed through the transformers as it is added to the Map. It is important not to use the original map after invoking this method, as it is a backdoor for adding untransformed objects.

If there are any elements already in the map being decorated, they are NOT transformed.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to transform, must not be null, typically empty

keyTransformer - the transformer for the map keys, null means no transformation

valueTransformer - the transformer for the map values, null means no transformation

Returns:

a transformed map backed by the given map

Throws:

java.lang.NullPointerException - if the Map is null

fixedSizeMap

public static <K,V> IterableMap<K,V> fixedSizeMap(java.util.Map<K,V> map)

Returns a fixed-sized map backed by the given map. Elements may not be added or removed from the returned map, but existing elements can be changed (for instance, via the Map.put(Object,Object) method).

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map whose size to fix, must not be null

Returns:

a fixed-size map backed by that map

Throws:

java.lang.NullPointerException - if the Map is null

lazyMap

public static <K,V> IterableMap<K,V> lazyMap(java.util.Map<K,V> map,
                                             Factory<? extends V> factory)

Returns a "lazy" map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key.

For instance:

 Factory factory = new Factory() {
     public Object create() {
         return new Date();
     }
 }
 Map lazyMap = MapUtils.lazyMap(new HashMap(), factory);
 Object obj = lazyMap.get("test");
 

After the above code is executed, obj will contain a new Date instance. Furthermore, that Date instance is the value for the "test" key in the map.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to make lazy, must not be null

factory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.NullPointerException - if the Map or Factory is null

lazyMap

public static <K,V> IterableMap<K,V> lazyMap(java.util.Map<K,V> map,
                                             Transformer<? super K,? extends V> transformerFactory)

Returns a "lazy" map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key. The factory is a Transformer that will be passed the key which it must transform into the value.

For instance:

 Transformer factory = new Transformer() {
     public Object transform(Object mapKey) {
         return new File(mapKey);
     }
 }
 Map lazyMap = MapUtils.lazyMap(new HashMap(), factory);
 Object obj = lazyMap.get("C:/dev");
 

After the above code is executed, obj will contain a new File instance for the C drive dev directory. Furthermore, that File instance is the value for the "C:/dev" key in the map.

If a lazy map is wrapped by a synchronized map, the result is a simple synchronized cache. When an object is not is the cache, the cache itself calls back to the factory Transformer to populate itself, all within the same synchronized block.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to make lazy, must not be null

transformerFactory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.NullPointerException - if the Map or Transformer is null

orderedMap

public static <K,V> OrderedMap<K,V> orderedMap(java.util.Map<K,V> map)

Returns a map that maintains the order of keys that are added backed by the given map.

If a key is added twice, the order is determined by the first add. The order is observed through the keySet, values and entrySet.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to order, must not be null

Returns:

an ordered map backed by the given map

Throws:

java.lang.NullPointerException - if the Map is null

multiValueMap

@Deprecated
public static <K,V> MultiValueMap<K,V> multiValueMap(java.util.Map<K,? super java.util.Collection<V>> map)

Deprecated. since 4.1, use MultiValuedMap instead

Creates a mult-value map backed by the given map which returns collections of type ArrayList.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to decorate

Returns:

a multi-value map backed by the given map which returns ArrayLists of values.

Since:

3.2

See Also:

MultiValueMap

multiValueMap

@Deprecated
public static <K,V,C extends java.util.Collection<V>> MultiValueMap<K,V> multiValueMap(java.util.Map<K,C> map,
                                                                                                   java.lang.Class<C> collectionClass)

Deprecated. since 4.1, use MultiValuedMap instead

Creates a multi-value map backed by the given map which returns collections of the specified type.

Type Parameters:

K - the key type

V - the value type

C - the collection class type

Parameters:

map - the map to decorate

collectionClass - the type of collections to return from the map (must contain public no-arg constructor and extend Collection)

Returns:

a multi-value map backed by the given map which returns collections of the specified type

Since:

3.2

See Also:

MultiValueMap

multiValueMap

@Deprecated
public static <K,V,C extends java.util.Collection<V>> MultiValueMap<K,V> multiValueMap(java.util.Map<K,C> map,
                                                                                                   Factory<C> collectionFactory)

Deprecated. since 4.1, use MultiValuedMap instead

Creates a multi-value map backed by the given map which returns collections created by the specified collection factory.

Type Parameters:

K - the key type

V - the value type

C - the collection class type

Parameters:

map - the map to decorate

collectionFactory - a factor which creates collection objects

Returns:

a multi-value map backed by the given map which returns collections created by the specified collection factory

Since:

3.2

See Also:

MultiValueMap

synchronizedSortedMap

public static <K,V> java.util.SortedMap<K,V> synchronizedSortedMap(java.util.SortedMap<K,V> map)

Returns a synchronized sorted map backed by the given sorted map.

You must manually synchronize on the returned buffer's iterator to avoid non-deterministic behavior:

 Map m = MapUtils.synchronizedSortedMap(myMap);
 Set s = m.keySet();  // outside synchronized block
 synchronized (m) {  // synchronized on MAP!
     Iterator i = s.iterator();
     while (i.hasNext()) {
         process (i.next());
     }
 }
 

This method uses the implementation in Collections.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to synchronize, must not be null

Returns:

a synchronized map backed by the given map

Throws:

java.lang.NullPointerException - if the map is null

unmodifiableSortedMap

public static <K,V> java.util.SortedMap<K,V> unmodifiableSortedMap(java.util.SortedMap<K,? extends V> map)

Returns an unmodifiable sorted map backed by the given sorted map.

This method uses the implementation in the decorators subpackage.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the sorted map to make unmodifiable, must not be null

Returns:

an unmodifiable map backed by the given map

Throws:

java.lang.NullPointerException - if the map is null

predicatedSortedMap

public static <K,V> java.util.SortedMap<K,V> predicatedSortedMap(java.util.SortedMap<K,V> map,
                                                                 Predicate<? super K> keyPred,
                                                                 Predicate<? super V> valuePred)

Returns a predicated (validating) sorted map backed by the given map.

Only objects that pass the tests in the given predicates can be added to the map. Trying to add an invalid object results in an IllegalArgumentException. Keys must pass the key predicate, values must pass the value predicate. It is important not to use the original map after invoking this method, as it is a backdoor for adding invalid objects.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to predicate, must not be null

keyPred - the predicate for keys, null means no check

valuePred - the predicate for values, null means no check

Returns:

a predicated map backed by the given map

Throws:

java.lang.NullPointerException - if the SortedMap is null

transformedSortedMap

public static <K,V> java.util.SortedMap<K,V> transformedSortedMap(java.util.SortedMap<K,V> map,
                                                                  Transformer<? super K,? extends K> keyTransformer,
                                                                  Transformer<? super V,? extends V> valueTransformer)

Returns a transformed sorted map backed by the given map.

This method returns a new sorted map (decorating the specified map) that will transform any new entries added to it. Existing entries in the specified map will not be transformed. If you want that behaviour, see TransformedSortedMap.transformedSortedMap(java.util.SortedMap<K, V>, org.apache.commons.collections4.Transformer<? super K, ? extends K>, org.apache.commons.collections4.Transformer<? super V, ? extends V>).

Each object is passed through the transformers as it is added to the Map. It is important not to use the original map after invoking this method, as it is a backdoor for adding untransformed objects.

If there are any elements already in the map being decorated, they are NOT transformed.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to transform, must not be null, typically empty

keyTransformer - the transformer for the map keys, null means no transformation

valueTransformer - the transformer for the map values, null means no transformation

Returns:

a transformed map backed by the given map

Throws:

java.lang.NullPointerException - if the SortedMap is null

fixedSizeSortedMap

public static <K,V> java.util.SortedMap<K,V> fixedSizeSortedMap(java.util.SortedMap<K,V> map)

Returns a fixed-sized sorted map backed by the given sorted map. Elements may not be added or removed from the returned map, but existing elements can be changed (for instance, via the Map.put(Object,Object) method).

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map whose size to fix, must not be null

Returns:

a fixed-size map backed by that map

Throws:

java.lang.NullPointerException - if the SortedMap is null

lazySortedMap

public static <K,V> java.util.SortedMap<K,V> lazySortedMap(java.util.SortedMap<K,V> map,
                                                           Factory<? extends V> factory)

Returns a "lazy" sorted map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key.

For instance:

 Factory factory = new Factory() {
     public Object create() {
         return new Date();
     }
 }
 SortedMap lazy = MapUtils.lazySortedMap(new TreeMap(), factory);
 Object obj = lazy.get("test");
 

After the above code is executed, obj will contain a new Date instance. Furthermore, that Date instance is the value for the "test" key.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to make lazy, must not be null

factory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.NullPointerException - if the SortedMap or Factory is null

lazySortedMap

public static <K,V> java.util.SortedMap<K,V> lazySortedMap(java.util.SortedMap<K,V> map,
                                                           Transformer<? super K,? extends V> transformerFactory)

Returns a "lazy" sorted map whose values will be created on demand.

When the key passed to the returned map's Map.get(Object) method is not present in the map, then the factory will be used to create a new object and that object will become the value associated with that key. The factory is a Transformer that will be passed the key which it must transform into the value.

For instance:

 Transformer factory = new Transformer() {
     public Object transform(Object mapKey) {
         return new File(mapKey);
     }
 }
 SortedMap lazy = MapUtils.lazySortedMap(new TreeMap(), factory);
 Object obj = lazy.get("C:/dev");
 

After the above code is executed, obj will contain a new File instance for the C drive dev directory. Furthermore, that File instance is the value for the "C:/dev" key in the map.

If a lazy map is wrapped by a synchronized map, the result is a simple synchronized cache. When an object is not is the cache, the cache itself calls back to the factory Transformer to populate itself, all within the same synchronized block.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the map to make lazy, must not be null

transformerFactory - the factory for creating new objects, must not be null

Returns:

a lazy map backed by the given map

Throws:

java.lang.NullPointerException - if the Map or Transformer is null

populateMap

public static <K,V> void populateMap(java.util.Map<K,V> map,
                                     java.lang.Iterable<? extends V> elements,
                                     Transformer<V,K> keyTransformer)

Populates a Map using the supplied Transformer to transform the elements into keys, using the unaltered element as the value in the Map.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the Map to populate.

elements - the Iterable containing the input values for the map.

keyTransformer - the Transformer used to transform the element into a key value

Throws:

java.lang.NullPointerException - if the map, elements or transformer are null

populateMap

public static <K,V,E> void populateMap(java.util.Map<K,V> map,
                                       java.lang.Iterable<? extends E> elements,
                                       Transformer<E,K> keyTransformer,
                                       Transformer<E,V> valueTransformer)

Populates a Map using the supplied Transformers to transform the elements into keys and values.

Type Parameters:

K - the key type

V - the value type

E - the type of object contained in the Iterable

Parameters:

map - the Map to populate.

elements - the Iterable containing the input values for the map.

keyTransformer - the Transformer used to transform the element into a key value

valueTransformer - the Transformer used to transform the element into a value

Throws:

java.lang.NullPointerException - if the map, elements or transformers are null

populateMap

public static <K,V> void populateMap(MultiMap<K,V> map,
                                     java.lang.Iterable<? extends V> elements,
                                     Transformer<V,K> keyTransformer)

Populates a MultiMap using the supplied Transformer to transform the elements into keys, using the unaltered element as the value in the MultiMap.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - the MultiMap to populate.

elements - the Iterable to use as input values for the map.

keyTransformer - the Transformer used to transform the element into a key value

Throws:

java.lang.NullPointerException - if the map, elements or transformer are null

populateMap

public static <K,V,E> void populateMap(MultiMap<K,V> map,
                                       java.lang.Iterable<? extends E> elements,
                                       Transformer<E,K> keyTransformer,
                                       Transformer<E,V> valueTransformer)

Populates a MultiMap using the supplied Transformers to transform the elements into keys and values.

Type Parameters:

K - the key type

V - the value type

E - the type of object contained in the Iterable

Parameters:

map - the MultiMap to populate.

elements - the Iterable containing the input values for the map.

keyTransformer - the Transformer used to transform the element into a key value

valueTransformer - the Transformer used to transform the element into a value

Throws:

java.lang.NullPointerException - if the map, collection or transformers are null

iterableMap

public static <K,V> IterableMap<K,V> iterableMap(java.util.Map<K,V> map)

Get the specified Map as an IterableMap.

Type Parameters:

K - the key type

V - the value type

Parameters:

map - to wrap if necessary.

Returns:

IterableMap

Throws:

java.lang.NullPointerException - if map is null

Since:

4.0

iterableSortedMap

public static <K,V> IterableSortedMap<K,V> iterableSortedMap(java.util.SortedMap<K,V> sortedMap)

Get the specified SortedMap as an IterableSortedMap.

Type Parameters:

K - the key type

V - the value type

Parameters:

sortedMap - to wrap if necessary

Returns:

IterableSortedMap

Throws:

java.lang.NullPointerException - if sortedMap is null

Since:

4.0