Class LinkedHashMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- java.lang.Object
-
- com.google.common.collect.LinkedHashMultimap<K,V>
-
- All Implemented Interfaces:
Multimap<K,V>
,SetMultimap<K,V>
,java.io.Serializable
@GwtCompatible(serializable=true, emulated=true) public final class LinkedHashMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> extends java.lang.Object
Implementation ofMultimap
that does not allow duplicate key-value entries and that returns collections whose iterators follow the ordering in which the data was added to the multimap.The collections returned by
keySet
,keys
, andasMap
iterate through the keys in the order they were first added to the multimap. Similarly,get
,removeAll
, andreplaceValues
return collections that iterate through the values in the order they were added. The collections generated byentries
andvalues
iterate across the key-value mappings in the order they were added to the multimap.The iteration ordering of the collections generated by
keySet
,keys
, andasMap
has a few subtleties. As long as the set of keys remains unchanged, adding or removing mappings does not affect the key iteration order. However, if you remove all values associated with a key and then add the key back to the multimap, that key will come last in the key iteration order.The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an existing key-value pair has no effect.
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.synchronizedSetMultimap(com.google.common.collect.SetMultimap<K, V>)
.Warning: Do not modify either a key or a value of a
LinkedHashMultimap
in a way that affects itsObject.equals(java.lang.Object)
behavior. Undefined behavior and bugs will result.See the Guava User Guide article on
Multimap
.- Since:
- 2.0
- Author:
- Jared Levy, Louis Wasserman
- See Also:
- Serialized Form
-
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description java.util.Map<K,java.util.Collection<V>>
asMap()
Returns a view of this multimap as aMap
from each distinct key to the nonempty collection of that key's associated values.void
clear()
Removes all key-value pairs from the multimap, leaving it empty.boolean
containsEntry(java.lang.Object key, java.lang.Object value)
Returnstrue
if this multimap contains at least one key-value pair with the keykey
and the valuevalue
.boolean
containsKey(java.lang.Object key)
Returnstrue
if this multimap contains at least one key-value pair with the keykey
.boolean
containsValue(java.lang.Object value)
Returnstrue
if this multimap contains at least one key-value pair with the valuevalue
.static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
LinkedHashMultimap<K,V>create()
Creates a new, emptyLinkedHashMultimap
with the default initial capacities.static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
LinkedHashMultimap<K,V>create(int expectedKeys, int expectedValuesPerKey)
Constructs an emptyLinkedHashMultimap
with enough capacity to hold the specified numbers of keys and values without rehashing.static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
LinkedHashMultimap<K,V>create(Multimap<? extends K,? extends V> multimap)
Constructs aLinkedHashMultimap
with the same mappings as the specified multimap.java.util.Set<java.util.Map.Entry<K,V>>
entries()
Returns a set of all key-value pairs.boolean
equals(java.lang.Object object)
Compares the specified object to this multimap for equality.java.util.Set<V>
get(K key)
Returns a view collection of the values associated withkey
in this multimap, if any.int
hashCode()
Returns the hash code for this multimap.boolean
isEmpty()
Returnstrue
if 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.java.util.Set<K>
keySet()
Returns a view collection of all distinct keys contained in this multimap.boolean
put(K key, V value)
Stores a key-value pair in the multimap.boolean
putAll(Multimap<? extends K,? extends V> multimap)
Stores all key-value pairs ofmultimap
in this multimap, in the order returned bymultimap.entries()
.boolean
putAll(K key, java.lang.Iterable<? extends V> values)
Stores a key-value pair in this multimap for each ofvalues
, all using the same key,key
.boolean
remove(java.lang.Object key, java.lang.Object value)
Removes a single key-value pair with the keykey
and the valuevalue
from this multimap, if such exists.java.util.Set<V>
removeAll(java.lang.Object key)
Removes all values associated with the keykey
.java.util.Set<V>
replaceValues(K key, java.lang.Iterable<? extends V> values)
Stores a collection of values with the same key, replacing any existing values for that key.int
size()
Returns the number of key-value pairs in this multimap.java.lang.String
toString()
Returns a string representation of the multimap, generated by callingtoString
on the map returned byMultimap.asMap()
.java.util.Collection<V>
values()
Returns a collection of all values in the multimap.-
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
-
Methods inherited from interface com.google.common.collect.Multimap
containsEntry, containsKey, containsValue, hashCode, isEmpty, keys, putAll, putAll, remove, size
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Method Detail
-
create
public static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> LinkedHashMultimap<K,V> create()
Creates a new, emptyLinkedHashMultimap
with the default initial capacities.
-
create
public static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> LinkedHashMultimap<K,V> create(int expectedKeys, int expectedValuesPerKey)
Constructs an emptyLinkedHashMultimap
with enough capacity to hold the specified numbers of keys and values without rehashing.- Parameters:
expectedKeys
- the expected number of distinct keysexpectedValuesPerKey
- the expected average number of values per key- Throws:
java.lang.IllegalArgumentException
- ifexpectedKeys
orexpectedValuesPerKey
is negative
-
create
public static <K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> LinkedHashMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
Constructs aLinkedHashMultimap
with the same mappings as the specified multimap. If a key-value mapping appears multiple times in the input multimap, it only appears once in the constructed multimap. The new multimap has the sameMultimap.entries()
iteration order as the input multimap, except for excluding duplicate mappings.- Parameters:
multimap
- the multimap whose contents are copied to this multimap
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replaceValues
@CanIgnoreReturnValue public java.util.Set<V> replaceValues(K key, java.lang.Iterable<? extends V> values)
Stores a collection of values with the same key, replacing any existing values for that key.If
values
is empty, this is equivalent toremoveAll(key)
.The returned collection is immutable.
Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.Any duplicates in
values
will be stored in the multimap once.If
values
is not empty and the multimap already contains a mapping forkey
, thekeySet()
ordering is unchanged. However, the provided values always come last in theentries()
andvalues()
iteration orderings.- Specified by:
replaceValues
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- Specified by:
replaceValues
in interfaceSetMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- 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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entries
public java.util.Set<java.util.Map.Entry<K,V>> entries()
Returns a set of all key-value pairs. Changes to the returned set will update the underlying multimap, and vice versa. The entries set does not support theadd
oraddAll
operations.The iterator generated by the returned set traverses the entries in the order they were added to the multimap.
Each entry is an immutable snapshot of a key-value mapping in the multimap, taken at the time the entry is returned by a method call to the collection or its iterator.
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keySet
public java.util.Set<K> keySet()
Returns 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.The iterator generated by the returned set traverses the keys in the order they were first added to the multimap.
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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values
public java.util.Collection<V> values()
Returns a collection of all values in the multimap. Changes to the returned collection will update the underlying multimap, and vice versa.The iterator generated by the returned collection traverses the values in the order they were added to the multimap.
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clear
public void clear()
Description copied from interface:Multimap
Removes all key-value pairs from the multimap, leaving it empty.
-
get
public java.util.Set<V> get(K key)
Returns a view collection of the values associated withkey
in 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.
The returned collection is not serializable.
Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.
-
removeAll
@CanIgnoreReturnValue public java.util.Set<V> removeAll(@CheckForNull java.lang.Object key)
Removes all values associated with the keykey
.Once this method returns,
key
will not be mapped to any values, so it will not appear inMultimap.keySet()
,Multimap.asMap()
, or any other views.The returned collection is immutable.
Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.- Specified by:
removeAll
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- Specified by:
removeAll
in interfaceSetMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- Returns:
- the values that were removed (possibly empty). The returned collection may be modifiable, but updating it will have no effect on the multimap.
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asMap
public java.util.Map<K,java.util.Collection<V>> asMap()
Returns a view of this multimap as aMap
from each distinct key to the nonempty collection of that key's associated values. Note thatthis.asMap().get(k)
is equivalent tothis.get(k)
only whenk
is a key contained in the multimap; otherwise it returnsnull
as 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
put
orputAll
, nor do its entries supportsetValue
.Though the method signature doesn't say so explicitly, the returned map has
Set
values.
-
put
@CanIgnoreReturnValue public boolean put(K key, V value)
Stores a key-value pair in the multimap.- Specified by:
put
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- Parameters:
key
- key to store in the multimapvalue
- value to store in the multimap- Returns:
true
if the method increased the size of the multimap, orfalse
if the multimap already contained the key-value pair
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equals
public boolean equals(@CheckForNull java.lang.Object object)
Compares the specified object to this multimap for equality.Two
SetMultimap
instances are equal if, for each key, they contain the same values. Equality does not depend on the ordering of keys or values.
-
size
public int size()
Description copied from interface:Multimap
Returns 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 theMultimap
class documentation for clarification.
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containsKey
public boolean containsKey(@CheckForNull java.lang.Object key)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the keykey
.- Specified by:
containsKey
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
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isEmpty
public boolean isEmpty()
Description copied from interface:Multimap
Returnstrue
if this multimap contains no key-value pairs. Equivalent tosize() == 0
, but can in some cases be more efficient.
-
containsValue
public boolean containsValue(@CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the valuevalue
.- Specified by:
containsValue
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
-
containsEntry
public boolean containsEntry(@CheckForNull java.lang.Object key, @CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the keykey
and the valuevalue
.- Specified by:
containsEntry
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
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remove
@CanIgnoreReturnValue public boolean remove(@CheckForNull java.lang.Object key, @CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Removes a single key-value pair with the keykey
and the valuevalue
from this multimap, if such exists. If multiple key-value pairs in the multimap fit this description, which one is removed is unspecified.
-
putAll
@CanIgnoreReturnValue public boolean putAll(K key, java.lang.Iterable<? extends V> values)
Description copied from interface:Multimap
Stores 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
values
is empty.
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putAll
@CanIgnoreReturnValue public boolean putAll(Multimap<? extends K,? extends V> multimap)
Description copied from interface:Multimap
Stores all key-value pairs ofmultimap
in this multimap, in the order returned bymultimap.entries()
.
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keys
public Multiset<K> keys()
Description copied from interface:Multimap
Returns 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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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()
.
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toString
public java.lang.String toString()
Returns a string representation of the multimap, generated by callingtoString
on the map returned byMultimap.asMap()
.- Overrides:
toString
in classjava.lang.Object
- Returns:
- a string representation of the multimap
-
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