Apache Commons Collections 4.4 · org.apache.commons.collections4.MultiMapUtils

Modifier and Type	Field and Description
public static final MultiValuedMap<K, V>	EMPTY_MULTI_VALUED_MAP An empty `UnmodifiableMultiValuedMap`.

Access	Constructor and Description
private	MultiMapUtils() `MultiMapUtils` should not normally be instantiated.

Method Summary

Modifier and Type	Method and Description
public static < the type of key in the map K, the type of value in the map V> MultiValuedMap<K, V>	Returns: an empty `MultiValuedMap` if the argument is null emptyIfNull(final MultiValuedMap<K, V> the map, may be null map) Returns an immutable empty `MultiValuedMap` if the argument is `null`, or the argument itself otherwise.
public static < the type of key in the map K, the type of value in the map V> MultiValuedMap<K, V>	Returns: immutable and empty `MultiValuedMap` emptyMultiValuedMap() Returns immutable EMPTY_MULTI_VALUED_MAP with generic type safety.
public static < the key type K, the value type V> Collection<V>	Returns: the Collection in the `MultiValuedMap`, or null if input map is null getCollection(final MultiValuedMap<K, V> the `MultiValuedMap` to use map, final K the key to look up key) Gets a Collection from `MultiValuedMap` in a null-safe manner.
public static < the key type K, the value type V> Bag<V>	Returns: the Collection in the `MultiValuedMap` as Bag, or null if input map is null getValuesAsBag(final MultiValuedMap<K, V> the `MultiValuedMap` to use map, final K the key to look up key) Gets a Bag from `MultiValuedMap` in a null-safe manner.
public static < the key type K, the value type V> List<V>	Returns: the Collection in the `MultiValuedMap` as List, or null if input map is null getValuesAsList(final MultiValuedMap<K, V> the `MultiValuedMap` to use map, final K the key to look up key) Gets a List from `MultiValuedMap` in a null-safe manner.
public static < the key type K, the value type V> Set<V>	Returns: the Collection in the `MultiValuedMap` as Set, or null if input map is null getValuesAsSet(final MultiValuedMap<K, V> the `MultiValuedMap` to use map, final K the key to look up key) Gets a Set from `MultiValuedMap` in a null-safe manner.
public static boolean	Returns: true if the map is empty or null isEmpty(final MultiValuedMap<?, ?> the map to check, may be null map) Null-safe check if the specified `MultiValuedMap` is empty.
public static < the key type K, the value type V> ListValuedMap<K, V>	Returns: a new `ListValuedMap` newListValuedHashMap() Creates a `ListValuedMap` with an `ArrayList` as collection class to store the values mapped to a key.
public static < the key type K, the value type V> SetValuedMap<K, V>	Returns: a new `SetValuedMap` newSetValuedHashMap() Creates a `SetValuedMap` with an `HashSet` as collection class to store the values mapped to a key.
public static < the key type K, the value type V> MultiValuedMap<K, V>	Returns: a transformed `MultiValuedMap` backed by the given map transformedMultiValuedMap(final MultiValuedMap<K, V> the `MultiValuedMap` to transform, must not be null, typically empty map, final Transformer<? super K, ? extends K> the transformer for the map keys, null means no transformation keyTransformer, final Transformer<? super V, ? extends V> the transformer for the map values, null means no transformation valueTransformer) Returns a `TransformedMultiValuedMap` backed by the given map.
public static < the key type K, the value type V> MultiValuedMap<K, V>	Returns: an unmodifiable `MultiValuedMap` backed by the provided map unmodifiableMultiValuedMap(final MultiValuedMap<? extends K, ? extends V> the `MultiValuedMap` to decorate, must not be null map) Returns an `UnmodifiableMultiValuedMap` backed by the given map.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

EMPTY_MULTI_VALUED_MAP	back to summary
public static final MultiValuedMap<K, V> EMPTY_MULTI_VALUED_MAP An empty `UnmodifiableMultiValuedMap`. Annotations @SuppressWarnings:rawtypes, unchecked

MultiMapUtils	back to summary
private MultiMapUtils() `MultiMapUtils` should not normally be instantiated.

Method Detail

emptyIfNull back to summary

emptyIfNull	back to summary
public static <K, V> MultiValuedMap<K, V> emptyIfNull(final MultiValuedMap<K, V> map) Returns an immutable empty `MultiValuedMap` if the argument is `null`, or the argument itself otherwise. Parameters <K> the type of key in the map <V> the type of value in the map map:MultiValuedMap<K, V> the map, may be null Returns:MultiValuedMap<K, V> an empty `MultiValuedMap` if the argument is null Annotations @SuppressWarnings:unchecked

public static <K, V> MultiValuedMap<K, V> emptyIfNull(final MultiValuedMap<K, V> map)

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

Parameters

<K>: the type of key in the map
<V>: the type of value in the map
map:MultiValuedMap<K, V>: the map, may be null

Returns:MultiValuedMap<K, V>

an empty MultiValuedMap if the argument is null

Annotations

@SuppressWarnings:unchecked

emptyMultiValuedMap back to summary

emptyMultiValuedMap	back to summary
public static <K, V> MultiValuedMap<K, V> emptyMultiValuedMap() Returns immutable EMPTY_MULTI_VALUED_MAP with generic type safety. Parameters <K> the type of key in the map <V> the type of value in the map Returns:MultiValuedMap<K, V> immutable and empty `MultiValuedMap` Annotations @SuppressWarnings:unchecked

public static <K, V> MultiValuedMap<K, V> emptyMultiValuedMap()

Returns immutable EMPTY_MULTI_VALUED_MAP with generic type safety.

Parameters

<K>: the type of key in the map
<V>: the type of value in the map

Returns:MultiValuedMap<K, V>

immutable and empty MultiValuedMap

Annotations

@SuppressWarnings:unchecked

getCollection back to summary

getCollection	back to summary
public static <K, V> Collection<V> getCollection(final MultiValuedMap<K, V> map, final K key) Gets a Collection from `MultiValuedMap` in a null-safe manner. Parameters <K> the key type <V> the value type map:MultiValuedMap<K, V> the `MultiValuedMap` to use key:K the key to look up Returns:Collection<V> the Collection in the `MultiValuedMap`, or null if input map is null

public static <K, V> Collection<V> getCollection(final MultiValuedMap<K, V> map, final K key)

Gets a Collection from MultiValuedMap in a null-safe manner.

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<K, V>: the MultiValuedMap to use
key:K: the key to look up

Returns:Collection<V>

the Collection in the MultiValuedMap, or null if input map is null

getValuesAsBag back to summary

getValuesAsBag	back to summary
public static <K, V> Bag<V> getValuesAsBag(final MultiValuedMap<K, V> map, final K key) Gets a Bag from `MultiValuedMap` in a null-safe manner. Parameters <K> the key type <V> the value type map:MultiValuedMap<K, V> the `MultiValuedMap` to use key:K the key to look up Returns:Bag<V> the Collection in the `MultiValuedMap` as Bag, or null if input map is null

public static <K, V> Bag<V> getValuesAsBag(final MultiValuedMap<K, V> map, final K key)

Gets a Bag from MultiValuedMap in a null-safe manner.

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<K, V>: the MultiValuedMap to use
key:K: the key to look up

Returns:Bag<V>

the Collection in the MultiValuedMap as Bag, or null if input map is null

getValuesAsList back to summary

getValuesAsList	back to summary
public static <K, V> List<V> getValuesAsList(final MultiValuedMap<K, V> map, final K key) Gets a List from `MultiValuedMap` in a null-safe manner. Parameters <K> the key type <V> the value type map:MultiValuedMap<K, V> the `MultiValuedMap` to use key:K the key to look up Returns:List<V> the Collection in the `MultiValuedMap` as List, or null if input map is null

public static <K, V> List<V> getValuesAsList(final MultiValuedMap<K, V> map, final K key)

Gets a List from MultiValuedMap in a null-safe manner.

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<K, V>: the MultiValuedMap to use
key:K: the key to look up

Returns:List<V>

the Collection in the MultiValuedMap as List, or null if input map is null

getValuesAsSet back to summary

getValuesAsSet	back to summary
public static <K, V> Set<V> getValuesAsSet(final MultiValuedMap<K, V> map, final K key) Gets a Set from `MultiValuedMap` in a null-safe manner. Parameters <K> the key type <V> the value type map:MultiValuedMap<K, V> the `MultiValuedMap` to use key:K the key to look up Returns:Set<V> the Collection in the `MultiValuedMap` as Set, or null if input map is null

public static <K, V> Set<V> getValuesAsSet(final MultiValuedMap<K, V> map, final K key)

Gets a Set from MultiValuedMap in a null-safe manner.

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<K, V>: the MultiValuedMap to use
key:K: the key to look up

Returns:Set<V>

the Collection in the MultiValuedMap as Set, or null if input map is null

isEmpty back to summary

isEmpty	back to summary
public static boolean isEmpty(final MultiValuedMap<?, ?> map) Null-safe check if the specified `MultiValuedMap` is empty. If the provided map is null, returns true. Parameters map:MultiValuedMap<?, ?> the map to check, may be null Returns:boolean true if the map is empty or null

public static boolean isEmpty(final MultiValuedMap<?, ?> map)

Null-safe check if the specified MultiValuedMap is empty.

If the provided map is null, returns true.

Parameters

map:MultiValuedMap<?, ?>: the map to check, may be null

Returns:boolean

true if the map is empty or null

newListValuedHashMap back to summary

newListValuedHashMap	back to summary
public static <K, V> ListValuedMap<K, V> newListValuedHashMap() Creates a `ListValuedMap` with an `ArrayList` as collection class to store the values mapped to a key. Parameters <K> the key type <V> the value type Returns:ListValuedMap<K, V> a new `ListValuedMap`

public static <K, V> ListValuedMap<K, V> newListValuedHashMap()

Creates a ListValuedMap with an ArrayList as collection class to store the values mapped to a key.

Parameters

<K>: the key type
<V>: the value type

Returns:ListValuedMap<K, V>

a new ListValuedMap

newSetValuedHashMap back to summary

newSetValuedHashMap	back to summary
public static <K, V> SetValuedMap<K, V> newSetValuedHashMap() Creates a `SetValuedMap` with an `HashSet` as collection class to store the values mapped to a key. Parameters <K> the key type <V> the value type Returns:SetValuedMap<K, V> a new `SetValuedMap`

public static <K, V> SetValuedMap<K, V> newSetValuedHashMap()

Creates a SetValuedMap with an HashSet as collection class to store the values mapped to a key.

Parameters

<K>: the key type
<V>: the value type

Returns:SetValuedMap<K, V>

a new SetValuedMap

transformedMultiValuedMap back to summary

transformedMultiValuedMap	back to summary
public static <K, V> MultiValuedMap<K, V> transformedMultiValuedMap(final MultiValuedMap<K, V> map, final Transformer<? super K, ? extends K> keyTransformer, final Transformer<? super V, ? extends V> valueTransformer) Returns a `TransformedMultiValuedMap` backed by the given map. This method returns a new `MultiValuedMap` (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 `TransformedMultiValuedMap#transformedMap`. 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 back door for adding untransformed objects. If there are any elements already in the map being decorated, they are NOT transformed. Parameters <K> the key type <V> the value type map:MultiValuedMap<K, V> the `MultiValuedMap` to transform, must not be null, typically empty keyTransformer:Transformer<? super K, ? extends K> the transformer for the map keys, null means no transformation valueTransformer:Transformer<? super V, ? extends V> the transformer for the map values, null means no transformation Returns:MultiValuedMap<K, V> a transformed `MultiValuedMap` backed by the given map Exceptions NullPointerException: if map is null

public static <K, V> MultiValuedMap<K, V> transformedMultiValuedMap(final MultiValuedMap<K, V> map, final Transformer<? super K, ? extends K> keyTransformer, final Transformer<? super V, ? extends V> valueTransformer)

Returns a TransformedMultiValuedMap backed by the given map.

This method returns a new MultiValuedMap (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 TransformedMultiValuedMap#transformedMap.

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 back door for adding untransformed objects.

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

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<K, V>: the MultiValuedMap to transform, must not be null, typically empty
keyTransformer:Transformer<? super K, ? extends K>: the transformer for the map keys, null means no transformation
valueTransformer:Transformer<? super V, ? extends V>: the transformer for the map values, null means no transformation

Returns:MultiValuedMap<K, V>

a transformed MultiValuedMap backed by the given map

Exceptions

NullPointerException:: if map is null

unmodifiableMultiValuedMap back to summary

unmodifiableMultiValuedMap	back to summary
public static <K, V> MultiValuedMap<K, V> unmodifiableMultiValuedMap(final MultiValuedMap<? extends K, ? extends V> map) Returns an `UnmodifiableMultiValuedMap` backed by the given map. Parameters <K> the key type <V> the value type map:MultiValuedMap<? extends K, ? extends V> the `MultiValuedMap` to decorate, must not be null Returns:MultiValuedMap<K, V> an unmodifiable `MultiValuedMap` backed by the provided map Exceptions NullPointerException: if map is null

public static <K, V> MultiValuedMap<K, V> unmodifiableMultiValuedMap(final MultiValuedMap<? extends K, ? extends V> map)

Returns an UnmodifiableMultiValuedMap backed by the given map.

Parameters

<K>: the key type
<V>: the value type
map:MultiValuedMap<? extends K, ? extends V>: the MultiValuedMap to decorate, must not be null

Returns:MultiValuedMap<K, V>

an unmodifiable MultiValuedMap backed by the provided map

Exceptions

NullPointerException:: if map is null

public Class MultiMapUtils

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