@GwtCompatible(serializable=true, emulated=true) public final class LinkedHashMultimap<K,V> extends Object
Implementation of Multimap 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, and asMap iterate through the keys in the order they were first added to the multimap. Similarly, get, removeAll, and replaceValues return collections that iterate through the values in the order they were added. The collections generated by entries and values 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, and asMap 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.diffplug.common.collect.SetMultimap<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> LinkedHashMultimap<K,V> |
create()
Creates a new, empty
LinkedHashMultimap with the default initial capacities. |
static <K,V> LinkedHashMultimap<K,V> |
create(int expectedKeys,
int expectedValuesPerKey)
Constructs an empty
LinkedHashMultimap with enough capacity to hold the specified numbers of keys and values without rehashing. |
static <K,V> LinkedHashMultimap<K,V> |
create(Multimap<? extends K,? extends V> multimap)
Constructs a
LinkedHashMultimap with the same mappings as the specified multimap. |
Set<Map.Entry<K,V>> |
entries()
Returns a set of all key-value pairs.
|
boolean |
equals(Object object)
Compares the specified object to this multimap for equality.
|
Set<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. |
Set<V> |
removeAll(Object key)
Removes all values associated with the key
key. |
Set<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(). |
Collection<V> |
values()
Returns a collection of all values in the multimap.
|
clone, finalize, getClass, notify, notifyAll, wait, wait, waitcontainsEntry, containsKey, containsValue, hashCode, isEmpty, keys, keySet, putAll, putAll, remove, sizepublic static <K,V> LinkedHashMultimap<K,V> create()
Creates a new, empty LinkedHashMultimap with the default initial capacities.
public static <K,V> LinkedHashMultimap<K,V> create(int expectedKeys, int expectedValuesPerKey)
Constructs an empty LinkedHashMultimap with enough capacity to hold the specified numbers of keys and values without rehashing.
expectedKeys - the expected number of distinct keysexpectedValuesPerKey - the expected average number of values per keyIllegalArgumentException - if expectedKeys or expectedValuesPerKey is negativepublic static <K,V> LinkedHashMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
Constructs a LinkedHashMultimap 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 same Multimap.entries() iteration order as the input multimap, except for excluding duplicate mappings.
multimap - the multimap whose contents are copied to this multimappublic Set<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).
The returned collection is immutable.
Because a SetMultimap has unique values for a given key, this
method returns a Set, instead of the Collection specified
in the Multimap interface.
Any duplicates in values will be stored in the multimap once.
If values is not empty and the multimap already contains a mapping for key, the keySet() ordering is unchanged. However, the provided values always come last in the entries() and values() iteration orderings.
replaceValues in interface Multimap<K,V>replaceValues in interface SetMultimap<K,V>public Set<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 the add or addAll 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.
public 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.
public void clear()
MultimapRemoves all key-value pairs from the multimap, leaving it empty.
public Set<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.
The returned collection is not serializable.
Because a SetMultimap has unique values for a given key, this
method returns a Set, instead of the Collection specified
in the Multimap interface.
public Set<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.
The returned collection is immutable.
Because a SetMultimap has unique values for a given key, this
method returns a Set, instead of the Collection specified
in the Multimap interface.
public 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. 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.
Though the method signature doesn't say so explicitly, the returned map
has Set values.
public boolean equals(@Nullable Object object)
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.
public int size()
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() or asMap().size(). See the opening section of the Multimap class documentation for clarification.
public boolean containsKey(@Nullable Object key)
MultimapReturns true if this multimap contains at least one key-value pair with the key key.
containsKey in interface Multimap<K,V>public boolean isEmpty()
MultimapReturns true if this multimap contains no key-value pairs. Equivalent to size() == 0, but can in some cases be more efficient.
public boolean containsValue(@Nullable Object value)
MultimapReturns true if this multimap contains at least one key-value pair with the value value.
containsValue in interface Multimap<K,V>public boolean containsEntry(@Nullable Object key, @Nullable Object value)
MultimapReturns 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)
MultimapRemoves 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)
MultimapStores 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)
MultimapStores all key-value pairs of multimap in this multimap, in the order returned by multimap.entries().
public Set<K> keySet()
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.
public Multiset<K> keys()
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, 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 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().