@GwtCompatible(serializable=true, emulated=true) public class LinkedListMultimap<K,V> extends Object implements ListMultimap<K,V>, Serializable
ListMultimap
that 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:
Multimap<K, V> multimap = LinkedListMultimap.create();
multimap.put(key1, foo);
multimap.put(key2, bar);
multimap.put(key1, baz);
... the iteration order for keys()
is [key1, key2, key1]
,
and similarly for entries()
. Unlike LinkedHashMultimap
, the
iteration order is kept consistent between keys, entries and values. For
example, calling:
map.remove(key1, foo);
changes the entries iteration order to [key2=bar, key1=baz]
and the
key iteration order to [key2, key1]
. The entries()
iterator
returns mutable map entries, and replaceValues(K, java.lang.Iterable<? extends V>)
attempts to preserve
iteration order as much as possible.
The collections returned by keySet()
and asMap
iterate
through the keys in the order they were first added to the multimap.
Similarly, get(K)
, removeAll(java.lang.Object)
, and replaceValues(K, java.lang.Iterable<? extends V>)
return collections that iterate through the values in the order they were
added. The collections generated by entries()
, keys()
, and
values()
iterate across the key-value mappings in the order they were
added to the multimap.
The values()
and entries()
methods both return a
List
, instead of the Collection
specified by the ListMultimap
interface.
The methods get(K)
, keySet()
, keys()
,
values()
, entries()
, and asMap
return 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
.
Modifier and Type | Method and Description |
---|---|
Map<K,Collection<V>> |
asMap()
Returns a view of this multimap as a
Map 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(Object key,
Object value)
Returns
true if this multimap contains at least one key-value pair
with the key key and the value value . |
boolean |
containsKey(Object key)
Returns
true if this multimap contains at least one key-value pair
with the key key . |
boolean |
containsValue(Object value)
Returns
true if this multimap contains at least one key-value pair
with the value value . |
static <K,V> LinkedListMultimap<K,V> |
create()
Creates a new, empty
LinkedListMultimap with the default initial
capacity. |
static <K,V> LinkedListMultimap<K,V> |
create(int expectedKeys)
Constructs an empty
LinkedListMultimap with 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 a
LinkedListMultimap with the same mappings as the
specified Multimap . |
List<Map.Entry<K,V>> |
entries()
Returns a view collection of all key-value pairs contained in this
multimap, as
Map.Entry instances. |
boolean |
equals(Object object)
Compares the specified object with this multimap for equality.
|
List<V> |
get(K key)
Returns a view collection of the values associated with
key in this
multimap, if any. |
int |
hashCode()
Returns the hash code for this multimap.
|
boolean |
isEmpty()
Returns
true 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.
|
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(K key,
Iterable<? extends V> values)
Stores a key-value pair in this multimap for each of
values , all
using the same key, key . |
boolean |
putAll(Multimap<? extends K,? extends V> multimap)
Stores all key-value pairs of
multimap in this multimap, in the
order returned by multimap.entries() . |
boolean |
remove(Object key,
Object value)
Removes a single key-value pair with the key
key and the value
value from this multimap, if such exists. |
List<V> |
removeAll(Object key)
Removes all values associated with the key
key . |
List<V> |
replaceValues(K key,
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.
|
String |
toString()
Returns a string representation of the multimap, generated by calling
toString on the map returned by Multimap.asMap() . |
List<V> |
values()
Returns a view collection containing the value from each key-value
pair contained in this multimap, without collapsing duplicates (so
values().size() == size() ). |
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
asMap, equals
public static <K,V> LinkedListMultimap<K,V> create()
LinkedListMultimap
with the default initial
capacity.public static <K,V> LinkedListMultimap<K,V> create(int expectedKeys)
LinkedListMultimap
with enough capacity to hold
the specified number of keys without rehashing.expectedKeys
- the expected number of distinct keysIllegalArgumentException
- if expectedKeys
is negativepublic static <K,V> LinkedListMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
LinkedListMultimap
with the same mappings as the
specified Multimap
. The new multimap has the same
Multimap.entries()
iteration order as the input multimap.multimap
- the multimap whose contents are copied to this multimappublic int size()
Multimap
Note: this method does not return the number of distinct
keys in the multimap, which is given by keySet().size()
or
asMap().size()
. See the opening section of the Multimap
class documentation for clarification.
public boolean isEmpty()
Multimap
true
if this multimap contains no key-value pairs.
Equivalent to size() == 0
, but can in some cases be more efficient.public boolean containsKey(@Nullable Object key)
Multimap
true
if this multimap contains at least one key-value pair
with the key key
.containsKey
in interface Multimap<K,V>
public boolean containsValue(@Nullable Object value)
Multimap
true
if this multimap contains at least one key-value pair
with the value value
.containsValue
in interface Multimap<K,V>
public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values)
If values
is empty, this is equivalent to
removeAll(key)
.
If any entries for the specified key
already exist in the
multimap, their values are changed in-place without affecting the iteration
order.
The returned list is immutable and implements
RandomAccess
.
replaceValues
in interface ListMultimap<K,V>
replaceValues
in interface Multimap<K,V>
public List<V> removeAll(@Nullable Object key)
key
.
Once this method returns, key
will not be mapped to any values,
so it will not appear in Multimap.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 the
Collection
specified in the Multimap
interface.
The returned list is immutable and implements
RandomAccess
.
public void clear()
Multimap
public List<V> get(@Nullable K key)
key
in this
multimap, if any. Note that when containsKey(key)
is false, this
returns an empty collection, not null
.
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 the
Collection
specified in the Multimap
interface.
If the multimap is modified while an iteration over the list is in
progress (except through the iterator's own add
, set
or
remove
operations) the results of the iteration are undefined.
The returned list is not serializable and does not have random access.
public List<V> values()
values().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 the Collection
specified in the ListMultimap
interface.
public List<Map.Entry<K,V>> entries()
Map.Entry
instances.
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 the Collection
specified in the ListMultimap
interface.
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, and Map.Entry.setValue(V)
modifies that value. Removing the mapping from the
multimap does not alter the value returned by getValue()
, though a
subsequent setValue()
call won't update the multimap but will lead
to a revised value being returned by getValue()
.
public boolean containsEntry(@Nullable Object key, @Nullable Object value)
Multimap
true
if this multimap contains at least one key-value pair
with the key key
and the value value
.containsEntry
in interface Multimap<K,V>
public boolean remove(@Nullable Object key, @Nullable Object value)
Multimap
key
and the value
value
from this multimap, if such exists. If multiple key-value
pairs in the multimap fit this description, which one is removed is
unspecified.public boolean putAll(@Nullable K key, Iterable<? extends V> values)
Multimap
values
, 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.
public boolean putAll(Multimap<? extends K,? extends V> multimap)
Multimap
multimap
in this multimap, in the
order returned by multimap.entries()
.public Set<K> keySet()
Multimap
Changes to the returned set will update the underlying multimap, and vice versa. However, adding to the returned set is not possible.
public Multiset<K> keys()
Multimap
keys().count(k) ==
get(k).size()
for all k
.
Changes to the returned multiset will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
public Map<K,Collection<V>> asMap()
Multimap
Map
from each distinct key
to the nonempty collection of that key's associated values. Note that
this.asMap().get(k)
is equivalent to this.get(k)
only when
k
is a key contained in the multimap; otherwise it returns null
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
or putAll
, nor do its entries support setValue
.
public boolean equals(@Nullable Object object)
Multimap
Multimap.asMap()
,
are also equal.
In general, two multimaps with identical key-value mappings may or may
not be equal, depending on the implementation. For example, two
SetMultimap
instances with the same key-value mappings are equal,
but equality of two ListMultimap
instances depends on the ordering
of the values for each key.
A non-empty SetMultimap
cannot be equal to a non-empty
ListMultimap
, since their Multimap.asMap()
views contain unequal
collections as values. However, any two empty multimaps are equal, because
they both have empty Multimap.asMap()
views.
public int hashCode()
The hash code of a multimap is defined as the hash code of the map view,
as returned by Multimap.asMap()
.
hashCode
in interface Multimap<K,V>
hashCode
in class Object
Map.hashCode()
public String toString()
toString
on the map returned by Multimap.asMap()
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