Class ArrayListMultimap<K,V>

All Implemented Interfaces:
ListMultimap<K,V>, Multimap<K,V>, Serializable

public final class ArrayListMultimap<K,V> extends ArrayListMultimapGwtSerializationDependencies<K,V>
Implementation of Multimap that uses an ArrayList to store the values for a given key. A HashMap associates each key with an ArrayList of values.

When iterating through the collections supplied by this class, the ordering of values for a given key agrees with the order in which the values were added.

This multimap allows duplicate key-value pairs. After adding a new key-value pair equal to an existing key-value pair, the ArrayListMultimap will contain entries for both the new value and the old value.

Keys and values may be null. All optional multimap methods are supported, and all returned views are modifiable.

The lists returned by AbstractListMultimap.get(K), AbstractListMultimap.removeAll(java.lang.Object), and AbstractListMultimap.replaceValues(K, java.lang.Iterable<? extends V>) all implement RandomAccess.

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

    • DEFAULT_VALUES_PER_KEY

      private static final int DEFAULT_VALUES_PER_KEY
      See Also:
    • expectedValuesPerKey

      transient int expectedValuesPerKey
    • serialVersionUID

      private static final long serialVersionUID
      See Also:
  • Constructor Details

    • ArrayListMultimap

      private ArrayListMultimap()
    • ArrayListMultimap

      private ArrayListMultimap(int expectedKeys, int expectedValuesPerKey)
    • ArrayListMultimap

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

    • create

      public static <K, V> ArrayListMultimap<K,V> create()
      Creates a new, empty ArrayListMultimap with the default initial capacities.

      You may also consider the equivalent MultimapBuilder.hashKeys().arrayListValues().build(), which provides more control over the underlying data structure.

    • create

      public static <K, V> ArrayListMultimap<K,V> create(int expectedKeys, int expectedValuesPerKey)
      Constructs an empty ArrayListMultimap with enough capacity to hold the specified numbers of keys and values without resizing.

      You may also consider the equivalent MultimapBuilder.hashKeys(expectedKeys).arrayListValues(expectedValuesPerKey).build(), which provides more control over the underlying data structure.

      Parameters:
      expectedKeys - the expected number of distinct keys
      expectedValuesPerKey - the expected average number of values per key
      Throws:
      IllegalArgumentException - if expectedKeys or expectedValuesPerKey is negative
    • create

      public static <K, V> ArrayListMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)
      Constructs an ArrayListMultimap with the same mappings as the specified multimap.

      You may also consider the equivalent MultimapBuilder.hashKeys().arrayListValues().build(multimap), which provides more control over the underlying data structure.

      Parameters:
      multimap - the multimap whose contents are copied to this multimap
    • createCollection

      List<V> createCollection()
      Creates a new, empty ArrayList to hold the collection of values for an arbitrary key.
      Specified by:
      createCollection in class AbstractListMultimap<K,V>
      Returns:
      an empty collection of values
    • trimToSize

      @Deprecated public void trimToSize()
      Deprecated.
      For a ListMultimap that automatically trims to size, use ImmutableListMultimap. If you need a mutable collection, remove the trimToSize call, or switch to a HashMap<K, ArrayList<V>>.
      Reduces the memory used by this ArrayListMultimap, if feasible.
    • writeObject

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

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