Interface MultiMap<K,V>
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- 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 aMapexcept that a key can be bound to multiple values. It is similar toMap<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 andsize()will be different. If you actually need theMap<K,Collection<V>>semantics, then call themap()method.- Author:
- cdivilly
- See Also:
size()
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Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description default booleancontainsKey(java.lang.Object key)Test if this object contains the specified key.java.util.Collection<java.util.Map.Entry<K,V>>entries()Get each key value pair in this multi-map.default Vget(java.lang.Object key)Get the first value associated with the specified key.default booleanisEmpty()Returns true if thisMultiMapcontains no key-value mappings.default java.util.Set<K>keySet()The set of keys in this objectjava.util.Map<K,java.util.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.java.util.Collection<V>values(java.lang.Object key)Get all the values associated with the specified key.
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Method Detail
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containsKey
default boolean containsKey(java.lang.Object key)
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
java.util.Collection<java.util.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
default V get(java.lang.Object key)
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
default java.util.Set<K> keySet()
The set of keys in this object- Returns:
- The key set
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map
java.util.Map<K,java.util.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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