@GwtCompatible(serializable=true, emulated=true) public class LinkedListMultimap<K,V> extends Object implements ListMultimap<K,V>, Serializable
An implementation of 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.diffplug.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()
Creates a new, empty LinkedListMultimap
with the default initial capacity.
public 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.
expectedKeys
- the expected number of distinct keysIllegalArgumentException
- if expectedKeys
is negativepublic static <K,V> LinkedListMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
Constructs a 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
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()
or asMap().size()
. See the opening section of the Multimap
class documentation for clarification.
public boolean isEmpty()
Multimap
Returns 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
Returns 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
Returns 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)
Stores a collection of values with the same key, replacing any existing values for that key.
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)
Removes all values associated with the 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
Removes all key-value pairs from the multimap, leaving it empty.
public List<V> get(@Nullable K key)
Returns a view collection of the values associated with 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()
Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (so 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()
Returns a view collection of all key-value pairs contained in this multimap, as 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
Returns 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
Removes a single key-value pair with the key 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
Stores a key-value pair in this multimap for each of 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
Stores all key-value pairs of multimap
in this multimap, in the order returned by multimap.entries()
.
public Set<K> keySet()
Multimap
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.
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
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, and 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
Returns a view of this multimap as a 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
Compares the specified object with this multimap for equality. Two multimaps are equal when their map views, as returned by 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()
.
public String toString()
toString
on the map returned by Multimap.asMap()
.