Class LinkedListMultimap<K,V>
- java.lang.Object
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- com.google.common.collect.LinkedListMultimap<K,V>
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- All Implemented Interfaces:
ListMultimap<K,V>,Multimap<K,V>,Serializable
@GwtCompatible(serializable=true, emulated=true) public class LinkedListMultimap<K,V> extends Object implements ListMultimap<K,V>, Serializable
An implementation ofListMultimapthat supports deterministic iteration order for both keys and values. The iteration order is preserved across non-distinct key values. For example, for the following multimap definition:
... the iteration order forMultimap<K, V> multimap = LinkedListMultimap.create(); multimap.put(key1, foo); multimap.put(key2, bar); multimap.put(key1, baz);Multimap.keys()is[key1, key2, key1], and similarly forentries(). UnlikeLinkedHashMultimap, the iteration order is kept consistent between keys, entries and values. For example, calling:multimap.remove(key1, foo);changes the entries iteration order to
[key2=bar, key1=baz]and the key iteration order to[key2, key1]. Theentries()iterator returns mutable map entries, andreplaceValues(K, java.lang.Iterable<? extends V>)attempts to preserve iteration order as much as possible.The collections returned by
Multimap.keySet()andasMapiterate through the keys in the order they were first added to the multimap. Similarly,get(K),removeAll(java.lang.Object), andreplaceValues(K, java.lang.Iterable<? extends V>)return collections that iterate through the values in the order they were added. The collections generated byentries(),Multimap.keys(), andvalues()iterate across the key-value mappings in the order they were added to the multimap.The
values()andentries()methods both return aList, instead of theCollectionspecified by theListMultimapinterface.The methods
get(K),Multimap.keySet(),Multimap.keys(),values(),entries(), andasMapreturn collections that are views of the multimap. If the multimap is modified while an iteration over any of those collections is in progress, except through the iterator's methods, the results of the iteration are undefined.Keys and values may be null. All optional multimap methods are supported, and all returned views are modifiable.
This class is not threadsafe when any concurrent operations update the multimap. Concurrent read operations will work correctly. To allow concurrent update operations, wrap your multimap with a call to
Multimaps.synchronizedListMultimap(com.google.common.collect.ListMultimap<K, V>).See the Guava User Guide article on
Multimap.- Since:
- 2.0
- Author:
- Mike Bostock
- See Also:
- Serialized Form
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description Map<K,Collection<V>>asMap()Returns a view of this multimap as aMapfrom each distinct key to the nonempty collection of that key's associated values.voidclear()Removes all key-value pairs from the multimap, leaving it empty.booleancontainsEntry(@Nullable Object key, @Nullable Object value)Returnstrueif this multimap contains at least one key-value pair with the keykeyand the valuevalue.booleancontainsKey(@Nullable Object key)Returnstrueif this multimap contains at least one key-value pair with the keykey.booleancontainsValue(@Nullable Object value)Returnstrueif this multimap contains at least one key-value pair with the valuevalue.static <K,V>
LinkedListMultimap<K,V>create()Creates a new, emptyLinkedListMultimapwith the default initial capacity.static <K,V>
LinkedListMultimap<K,V>create(int expectedKeys)Constructs an emptyLinkedListMultimapwith enough capacity to hold the specified number of keys without rehashing.static <K,V>
LinkedListMultimap<K,V>create(Multimap<? extends K,? extends V> multimap)Constructs aLinkedListMultimapwith the same mappings as the specifiedMultimap.List<Map.Entry<K,V>>entries()Returns a view collection of all key-value pairs contained in this multimap, asMap.Entryinstances.booleanequals(@Nullable Object object)Indicates whether some other object is "equal to" this one.List<V>get(@Nullable K key)Returns a view collection of the values associated withkeyin this multimap, if any.inthashCode()Returns the hash code for this multimap.booleanisEmpty()Returnstrueif this multimap contains no key-value pairs.Multiset<K>keys()Returns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates.Set<K>keySet()Returns a view collection of all distinct keys contained in this multimap.booleanput(@Nullable K key, @Nullable V value)Stores a key-value pair in the multimap.booleanputAll(@Nullable K key, Iterable<? extends V> values)Stores a key-value pair in this multimap for each ofvalues, all using the same key,key.booleanputAll(Multimap<? extends K,? extends V> multimap)Stores all key-value pairs ofmultimapin this multimap, in the order returned bymultimap.entries().booleanremove(@Nullable Object key, @Nullable Object value)Removes a single key-value pair with the keykeyand the valuevaluefrom this multimap, if such exists.List<V>removeAll(@Nullable Object key)Removes all values associated with the keykey.List<V>replaceValues(@Nullable K key, Iterable<? extends V> values)Stores a collection of values with the same key, replacing any existing values for that key.intsize()Returns the number of key-value pairs in this multimap.StringtoString()Returns a string representation of the multimap, generated by callingtoStringon the map returned byMultimap.asMap().List<V>values()Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (sovalues().size() == size()).-
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface com.google.common.collect.ListMultimap
asMap, equals
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Method Detail
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create
public static <K,V> LinkedListMultimap<K,V> create()
Creates a new, emptyLinkedListMultimapwith the default initial capacity.
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create
public static <K,V> LinkedListMultimap<K,V> create(int expectedKeys)
Constructs an emptyLinkedListMultimapwith enough capacity to hold the specified number of keys without rehashing.- Parameters:
expectedKeys- the expected number of distinct keys- Throws:
IllegalArgumentException- ifexpectedKeysis negative
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create
public static <K,V> LinkedListMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
Constructs aLinkedListMultimapwith the same mappings as the specifiedMultimap. The new multimap has the sameMultimap.entries()iteration order as the input multimap.- Parameters:
multimap- the multimap whose contents are copied to this multimap
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size
public int size()
Description copied from interface:MultimapReturns the number of key-value pairs in this multimap.Note: this method does not return the number of distinct keys in the multimap, which is given by
keySet().size()orasMap().size(). See the opening section of theMultimapclass documentation for clarification.
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isEmpty
public boolean isEmpty()
Description copied from interface:MultimapReturnstrueif this multimap contains no key-value pairs. Equivalent tosize() == 0, but can in some cases be more efficient.
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containsKey
public boolean containsKey(@Nullable Object key)
Description copied from interface:MultimapReturnstrueif this multimap contains at least one key-value pair with the keykey.- Specified by:
containsKeyin interfaceMultimap<K,V>
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containsValue
public boolean containsValue(@Nullable Object value)
Description copied from interface:MultimapReturnstrueif this multimap contains at least one key-value pair with the valuevalue.- Specified by:
containsValuein interfaceMultimap<K,V>
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put
@CanIgnoreReturnValue public boolean put(@Nullable K key, @Nullable V value)
Stores a key-value pair in the multimap.
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replaceValues
@CanIgnoreReturnValue public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values)
Stores a collection of values with the same key, replacing any existing values for that key.If
valuesis empty, this is equivalent toremoveAll(key).If any entries for the specified
keyalready exist in the multimap, their values are changed in-place without affecting the iteration order.The returned list is immutable and implements
RandomAccess.- Specified by:
replaceValuesin interfaceListMultimap<K,V>- Specified by:
replaceValuesin interfaceMultimap<K,V>- Returns:
- the collection of replaced values, or an empty collection if no values were previously associated with the key. The collection may be modifiable, but updating it will have no effect on the multimap.
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removeAll
@CanIgnoreReturnValue public List<V> removeAll(@Nullable Object key)
Removes all values associated with the keykey.Once this method returns,
keywill not be mapped to any values, so it will not appear inMultimap.keySet(),Multimap.asMap(), or any other views.Because the values for a given key may have duplicates and follow the insertion ordering, this method returns a
List, instead of theCollectionspecified in theMultimapinterface.The returned list is immutable and implements
RandomAccess.
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clear
public void clear()
Description copied from interface:MultimapRemoves all key-value pairs from the multimap, leaving it empty.
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get
public List<V> get(@Nullable K key)
Returns a view collection of the values associated withkeyin this multimap, if any. Note that whencontainsKey(key)is false, this returns an empty collection, notnull.Changes to the returned collection will update the underlying multimap, and vice versa.
Because the values for a given key may have duplicates and follow the insertion ordering, this method returns a
List, instead of theCollectionspecified in theMultimapinterface.If the multimap is modified while an iteration over the list is in progress (except through the iterator's own
add,setorremoveoperations) the results of the iteration are undefined.The returned list is not serializable and does not have random access.
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values
public List<V> values()
Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (sovalues().size() == size()).Changes to the returned collection will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
The iterator generated by the returned collection traverses the values in the order they were added to the multimap. Because the values may have duplicates and follow the insertion ordering, this method returns a
List, instead of theCollectionspecified in theListMultimapinterface.
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entries
public List<Map.Entry<K,V>> entries()
Returns a view collection of all key-value pairs contained in this multimap, asMap.Entryinstances.Changes to the returned collection or the entries it contains will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
The iterator generated by the returned collection traverses the entries in the order they were added to the multimap. Because the entries may have duplicates and follow the insertion ordering, this method returns a
List, instead of theCollectionspecified in theListMultimapinterface.An entry's
Map.Entry.getKey()method always returns the same key, regardless of what happens subsequently. As long as the corresponding key-value mapping is not removed from the multimap,Map.Entry.getValue()returns the value from the multimap, which may change over time, andMap.Entry.setValue(V)modifies that value. Removing the mapping from the multimap does not alter the value returned bygetValue(), though a subsequentsetValue()call won't update the multimap but will lead to a revised value being returned bygetValue().
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containsEntry
public boolean containsEntry(@Nullable Object key, @Nullable Object value)
Description copied from interface:MultimapReturnstrueif this multimap contains at least one key-value pair with the keykeyand the valuevalue.- Specified by:
containsEntryin interfaceMultimap<K,V>
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remove
@CanIgnoreReturnValue public boolean remove(@Nullable Object key, @Nullable Object value)
Description copied from interface:MultimapRemoves a single key-value pair with the keykeyand the valuevaluefrom this multimap, if such exists. If multiple key-value pairs in the multimap fit this description, which one is removed is unspecified.
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putAll
@CanIgnoreReturnValue public boolean putAll(@Nullable K key, Iterable<? extends V> values)
Description copied from interface:MultimapStores a key-value pair in this multimap for each ofvalues, all using the same key,key. Equivalent to (but expected to be more efficient than):for (V value : values) { put(key, value); }In particular, this is a no-op if
valuesis empty.
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putAll
@CanIgnoreReturnValue public boolean putAll(Multimap<? extends K,? extends V> multimap)
Description copied from interface:MultimapStores all key-value pairs ofmultimapin this multimap, in the order returned bymultimap.entries().
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keySet
public Set<K> keySet()
Description copied from interface:MultimapReturns a view collection of all distinct keys contained in this multimap. Note that the key set contains a key if and only if this multimap maps that key to at least one value.Changes to the returned set will update the underlying multimap, and vice versa. However, adding to the returned set is not possible.
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keys
public Multiset<K> keys()
Description copied from interface:MultimapReturns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates. This collection has the same size as this multimap, andkeys().count(k) == get(k).size()for allk.Changes to the returned multiset will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
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asMap
public Map<K,Collection<V>> asMap()
Description copied from interface:MultimapReturns a view of this multimap as aMapfrom each distinct key to the nonempty collection of that key's associated values. Note thatthis.asMap().get(k)is equivalent tothis.get(k)only whenkis a key contained in the multimap; otherwise it returnsnullas opposed to an empty collection.Changes to the returned map or the collections that serve as its values will update the underlying multimap, and vice versa. The map does not support
putorputAll, nor do its entries supportsetValue.
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equals
public boolean equals(@Nullable Object object)
Description copied from class:java.lang.ObjectIndicates whether some other object is "equal to" this one.The
equalsmethod implements an equivalence relation on non-null object references:- It is reflexive: for any non-null reference value
x,x.equals(x)should returntrue. - It is symmetric: for any non-null reference values
xandy,x.equals(y)should returntrueif and only ify.equals(x)returnstrue. - It is transitive: for any non-null reference values
x,y, andz, ifx.equals(y)returnstrueandy.equals(z)returnstrue, thenx.equals(z)should returntrue. - It is consistent: for any non-null reference values
xandy, multiple invocations ofx.equals(y)consistently returntrueor consistently returnfalse, provided no information used inequalscomparisons on the objects is modified. - For any non-null reference value
x,x.equals(null)should returnfalse.
The
equalsmethod for classObjectimplements the most discriminating possible equivalence relation on objects; that is, for any non-null reference valuesxandy, this method returnstrueif and only ifxandyrefer to the same object (x == yhas the valuetrue).Note that it is generally necessary to override the
hashCodemethod whenever this method is overridden, so as to maintain the general contract for thehashCodemethod, which states that equal objects must have equal hash codes. - It is reflexive: for any non-null reference value
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hashCode
public int hashCode()
Returns the hash code for this multimap.The hash code of a multimap is defined as the hash code of the map view, as returned by
Multimap.asMap().- Specified by:
hashCodein interfaceMultimap<K,V>- Overrides:
hashCodein classObject- Returns:
- a hash code value for this object.
- See Also:
Map.hashCode()
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toString
public String toString()
Returns a string representation of the multimap, generated by callingtoStringon the map returned byMultimap.asMap().
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