Interface MultiMap<K,V>
- Type Parameters:
K- the type of keys maintained by this multimapV- the type of mapped values
public interface MultiMap<K,V>
A MultiMap is like a
Map except that a key can be bound to multiple values. It is similar to
Map<K,Collection<V>>, but not identical because in a multimap, each key and value is stored as an
individual entry. This means that the iteration order and size() will be different.
If you actually need the Map<K,Collection<V>> semantics, then call the map() method.- Author:
- cdivilly
- See Also:
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Method Summary
Modifier and TypeMethodDescriptiondefault booleancontainsKey(Object key) Test if this object contains the specified key.entries()Get each key value pair in this multi-map.default VGet the first value associated with the specified key.default booleanisEmpty()Returns true if thisMultiMapcontains no key-value mappings.keySet()The set of keys in this objectMap<K,Collection<V>> map()Represent thisMultiMapas aMap<K,Collection<V>>data structure, where values are grouped by key.default intsize()The number of entries in thisMultiMap.Get all the values associated with the specified key.
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Method Details
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containsKey
Test if this object contains the specified key.- Parameters:
key- The key to search for- Returns:
- true if the key exists, false otherwise
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entries
Collection<Map.Entry<K,V>> entries()Get each key value pair in this multi-map.- Returns:
Collectionof allMap.Entrys in this multi map.
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get
Get the first value associated with the specified key.- Parameters:
key- The key to search for- Returns:
- The first value associated with the key, or null if no values are associated with the key
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isEmpty
default boolean isEmpty()Returns true if thisMultiMapcontains no key-value mappings.- Returns:
- true if this
MultiMapcontains no key-value mappings
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keySet
The set of keys in this object- Returns:
- The key set
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map
Map<K,Collection<V>> map()Represent thisMultiMapas aMap<K,Collection<V>>data structure, where values are grouped by key.- Returns:
Mapinstance
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size
default int size()The number of entries in thisMultiMap. Note that this method returns the number of entries, not the number of keys as aMapwould. Consider the followingMultiMap{ a = b, c = d, a = e }Thesize()of thisMultiMapis3. Note that theMap.size()value returned by theMapinstance returned from themap()method would be2, because there are only two distinct keys.- Returns:
- the number of values in the multimap
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values
Get all the values associated with the specified key.- Parameters:
key- The name of the key- Returns:
- The values associated with the key, or returns null if the key is not present in the
MultiMap
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