Class MultiMapUtils
MultiValuedMap instances.
 It contains various type safe and null safe methods. Additionally, it provides the following decorators:
- Since:
- 4.1
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Field SummaryFieldsModifier and TypeFieldDescriptionstatic final MultiValuedMapAn emptyUnmodifiableMultiValuedMap.
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Method SummaryModifier and TypeMethodDescriptionstatic <K,V> MultiValuedMap <K, V> emptyIfNull(MultiValuedMap<K, V> map) Returns an immutable emptyMultiValuedMapif the argument isnull, or the argument itself otherwise.static <K,V> MultiValuedMap <K, V> Returns immutable EMPTY_MULTI_VALUED_MAP with generic type safety.static <K,V> Collection <V> getCollection(MultiValuedMap<K, V> map, K key) Gets a Collection fromMultiValuedMapin a null-safe manner.static <K,V> Bag <V> getValuesAsBag(MultiValuedMap<K, V> map, K key) Gets a Bag fromMultiValuedMapin a null-safe manner.static <K,V> List <V> getValuesAsList(MultiValuedMap<K, V> map, K key) Gets a List fromMultiValuedMapin a null-safe manner.static <K,V> Set <V> getValuesAsSet(MultiValuedMap<K, V> map, K key) Gets a Set fromMultiValuedMapin a null-safe manner.static booleanisEmpty(MultiValuedMap<?, ?> map) Null-safe check if the specifiedMultiValuedMapis empty.static <K,V> ListValuedMap <K, V> Creates aListValuedMapwith anArrayListas collection class to store the values mapped to a key.static <K,V> SetValuedMap <K, V> Creates aSetValuedMapwith anHashSetas collection class to store the values mapped to a key.static <K,V> MultiValuedMap <K, V> transformedMultiValuedMap(MultiValuedMap<K, V> map, Transformer<? super K, ? extends K> keyTransformer, Transformer<? super V, ? extends V> valueTransformer) Returns aTransformedMultiValuedMapbacked by the given map.static <K,V> MultiValuedMap <K, V> unmodifiableMultiValuedMap(MultiValuedMap<? extends K, ? extends V> map) Returns anUnmodifiableMultiValuedMapbacked by the given map.
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Field Details- 
EMPTY_MULTI_VALUED_MAPAn emptyUnmodifiableMultiValuedMap.
 
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Method Details- 
emptyIfNullReturns an immutable emptyMultiValuedMapif the argument isnull, or the argument itself otherwise.- Type Parameters:
- K- the type of key in the map
- V- the type of value in the map
- Parameters:
- map- the map, may be null
- Returns:
- an empty MultiValuedMapif the argument is null
 
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emptyMultiValuedMapReturns immutable EMPTY_MULTI_VALUED_MAP with generic type safety.- Type Parameters:
- K- the type of key in the map
- V- the type of value in the map
- Returns:
- immutable and empty MultiValuedMap
 
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getCollectionGets a Collection fromMultiValuedMapin a null-safe manner.- Type Parameters:
- K- the key type
- V- the value type
- Parameters:
- map- the- MultiValuedMapto use
- key- the key to look up
- Returns:
- the Collection in the MultiValuedMap, or null if input map is null
 
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getValuesAsBagGets a Bag fromMultiValuedMapin a null-safe manner.- Type Parameters:
- K- the key type
- V- the value type
- Parameters:
- map- the- MultiValuedMapto use
- key- the key to look up
- Returns:
- the Collection in the MultiValuedMapas Bag, or null if input map is null
 
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getValuesAsListGets a List fromMultiValuedMapin a null-safe manner.- Type Parameters:
- K- the key type
- V- the value type
- Parameters:
- map- the- MultiValuedMapto use
- key- the key to look up
- Returns:
- the Collection in the MultiValuedMapas List, or null if input map is null
 
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getValuesAsSetGets a Set fromMultiValuedMapin a null-safe manner.- Type Parameters:
- K- the key type
- V- the value type
- Parameters:
- map- the- MultiValuedMapto use
- key- the key to look up
- Returns:
- the Collection in the MultiValuedMapas Set, or null if input map is null
 
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isEmptyNull-safe check if the specifiedMultiValuedMapis empty.If the provided map is null, returns true. - Parameters:
- map- the map to check, may be null
- Returns:
- true if the map is empty or null
 
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newListValuedHashMapCreates aListValuedMapwith anArrayListas collection class to store the values mapped to a key.- Type Parameters:
- K- the key type
- V- the value type
- Returns:
- a new ListValuedMap
 
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newSetValuedHashMapCreates aSetValuedMapwith anHashSetas collection class to store the values mapped to a key.- Type Parameters:
- K- the key type
- V- the value type
- Returns:
- a new SetValuedMap
 
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transformedMultiValuedMappublic static <K,V> MultiValuedMap<K,V> transformedMultiValuedMap(MultiValuedMap<K, V> map, Transformer<? super K, ? extends K> keyTransformer, Transformer<? super V, ? extends V> valueTransformer) Returns aTransformedMultiValuedMapbacked 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 behavior, seeTransformedMultiValuedMap.transformedMap(org.apache.commons.collections4.MultiValuedMap<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 back door 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- MultiValuedMapto 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 MultiValuedMapbacked by the given map
- Throws:
- NullPointerException- if map is null
 
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unmodifiableMultiValuedMappublic static <K,V> MultiValuedMap<K,V> unmodifiableMultiValuedMap(MultiValuedMap<? extends K, ? extends V> map) Returns anUnmodifiableMultiValuedMapbacked by the given map.- Type Parameters:
- K- the key type
- V- the value type
- Parameters:
- map- the- MultiValuedMapto decorate, must not be null
- Returns:
- an unmodifiable MultiValuedMapbacked by the provided map
- Throws:
- NullPointerException- if map is null
 
 
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