Class LinkedListMultimap<K,V>

java.lang.Object
com.google.common.collect.AbstractMultimap<K,V>
com.google.common.collect.LinkedListMultimap<K,V>
All Implemented Interfaces:
ListMultimap<K,V>, Multimap<K,V>, Serializable

public class LinkedListMultimap<K,V> extends AbstractMultimap<K,V> 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 AbstractMultimap.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:

 multimap.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 AbstractMultimap.keySet() and AbstractMultimap.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(), AbstractMultimap.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), AbstractMultimap.keySet(), AbstractMultimap.keys(), values(), entries(), and AbstractMultimap.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.

Since:
2.0
See Also:
  • Field Details

  • Constructor Details

    • LinkedListMultimap

      LinkedListMultimap()
    • LinkedListMultimap

      private LinkedListMultimap(int expectedKeys)
    • LinkedListMultimap

      private LinkedListMultimap(Multimap<? extends K,? extends V> multimap)
  • Method Details

    • create

      public static <K, V> LinkedListMultimap<K,V> create()
      Creates a new, empty LinkedListMultimap with the default initial capacity.
    • create

      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.
      Parameters:
      expectedKeys - the expected number of distinct keys
      Throws:
      IllegalArgumentException - if expectedKeys is negative
    • create

      public 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.
      Parameters:
      multimap - the multimap whose contents are copied to this multimap
    • addNode

      private LinkedListMultimap.Node<K,V> addNode(K key, V value, @CheckForNull LinkedListMultimap.Node<K,V> nextSibling)
      Adds a new node for the specified key-value pair before the specified nextSibling element, or at the end of the list if nextSibling is null. Note: if nextSibling is specified, it MUST be for a node for the same key!
    • removeNode

      private void removeNode(LinkedListMultimap.Node<K,V> node)
      Removes the specified node from the linked list. This method is only intended to be used from the Iterator classes. See also removeAllNodes(Object).
    • removeAllNodes

      private void removeAllNodes(K key)
      Removes all nodes for the specified key.
    • 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() or asMap().size(). See the opening section of the Multimap class documentation for clarification.

      Specified by:
      size in interface Multimap<K,V>
    • isEmpty

      public boolean isEmpty()
      Description copied from interface: Multimap
      Returns true if this multimap contains no key-value pairs. Equivalent to size() == 0, but can in some cases be more efficient.
      Specified by:
      isEmpty in interface Multimap<K,V>
      Overrides:
      isEmpty in class AbstractMultimap<K,V>
    • containsKey

      public boolean containsKey(@CheckForNull Object key)
      Description copied from interface: Multimap
      Returns true if this multimap contains at least one key-value pair with the key key.
      Specified by:
      containsKey in interface Multimap<K,V>
    • containsValue

      public boolean containsValue(@CheckForNull Object value)
      Description copied from interface: Multimap
      Returns true if this multimap contains at least one key-value pair with the value value.
      Specified by:
      containsValue in interface Multimap<K,V>
      Overrides:
      containsValue in class AbstractMultimap<K,V>
    • put

      public boolean put(K key, V value)
      Stores a key-value pair in the multimap.
      Specified by:
      put in interface Multimap<K,V>
      Overrides:
      put in class AbstractMultimap<K,V>
      Parameters:
      key - key to store in the multimap
      value - value to store in the multimap
      Returns:
      true always
    • replaceValues

      public 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.

      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.

      Specified by:
      replaceValues in interface ListMultimap<K,V>
      Specified by:
      replaceValues in interface Multimap<K,V>
      Overrides:
      replaceValues in class AbstractMultimap<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.
    • getCopy

      private List<V> getCopy(K key)
    • removeAll

      public List<V> removeAll(@CheckForNull 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.

      Specified by:
      removeAll in interface ListMultimap<K,V>
      Specified by:
      removeAll in interface Multimap<K,V>
      Returns:
      the values that were removed (possibly empty). The returned collection may be modifiable, but updating it will have no effect on the multimap.
    • clear

      public void clear()
      Description copied from interface: Multimap
      Removes all key-value pairs from the multimap, leaving it empty.
      Specified by:
      clear in interface Multimap<K,V>
    • get

      public List<V> get(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.

      Specified by:
      get in interface ListMultimap<K,V>
      Specified by:
      get in interface Multimap<K,V>
    • createKeySet

      Set<K> createKeySet()
      Specified by:
      createKeySet in class AbstractMultimap<K,V>
    • createKeys

      Multiset<K> createKeys()
      Specified by:
      createKeys in class AbstractMultimap<K,V>
    • values

      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.

      Specified by:
      values in interface Multimap<K,V>
      Overrides:
      values in class AbstractMultimap<K,V>
    • createValues

      List<V> createValues()
      Specified by:
      createValues in class AbstractMultimap<K,V>
    • entries

      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().

      Specified by:
      entries in interface Multimap<K,V>
      Overrides:
      entries in class AbstractMultimap<K,V>
    • createEntries

      List<Map.Entry<K,V>> createEntries()
      Specified by:
      createEntries in class AbstractMultimap<K,V>
    • entryIterator

      Iterator<Map.Entry<K,V>> entryIterator()
      Specified by:
      entryIterator in class AbstractMultimap<K,V>
    • createAsMap

      Map<K,Collection<V>> createAsMap()
      Specified by:
      createAsMap in class AbstractMultimap<K,V>
    • writeObject

      private void writeObject(ObjectOutputStream stream) throws IOException
      Throws:
      IOException
    • readObject

      private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException
      Throws:
      IOException
      ClassNotFoundException