Package com.google.common.collect

Class ForwardingMultimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

  • All Implemented Interfaces:
    Multimap<K,​V>
    Direct Known Subclasses:
    ForwardingListMultimap, ForwardingSetMultimap
    @GwtCompatible
public abstract class ForwardingMultimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
extends ForwardingObject
implements Multimap<K,​V>
    A multimap which forwards all its method calls to another multimap. Subclasses should override one or more methods to modify the behavior of the backing multimap as desired per the decorator pattern.

    default method warning: This class does not forward calls to default methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingMultimap.

    Since:
    2.0
    Author:
    Robert Konigsberg

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      protected ForwardingMultimap()
      Constructor for use by subclasses.

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      java.util.Map<K,​java.util.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​(java.lang.Object key, java.lang.Object value)
      Returns true if this multimap contains at least one key-value pair with the key key and the value value.
      boolean containsKey​(java.lang.Object key)
      Returns true if this multimap contains at least one key-value pair with the key key.
      boolean containsValue​(java.lang.Object value)
      Returns true if this multimap contains at least one key-value pair with the value value.
      protected abstract Multimap<K,​V> delegate()
      Returns the backing delegate instance that methods are forwarded to.
      java.util.Collection<java.util.Map.Entry<K,​V>> entries()
      Returns a view collection of all key-value pairs contained in this multimap, as Map.Entry instances.
      boolean equals​(java.lang.Object object)
      Compares the specified object with this multimap for equality.
      java.util.Collection<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.
      java.util.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 this multimap.
      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 putAll​(K key, java.lang.Iterable<? extends V> values)
      Stores a key-value pair in this multimap for each of values, all using the same key, key.
      boolean remove​(java.lang.Object key, java.lang.Object value)
      Removes a single key-value pair with the key key and the value value from this multimap, if such exists.
      java.util.Collection<V> removeAll​(java.lang.Object key)
      Removes all values associated with the key key.
      java.util.Collection<V> replaceValues​(K key, java.lang.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.
      java.util.Collection<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()).

      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait

    • Constructor Detail

    • Method Detail

      • delegate

        protected abstract Multimap<K,​V> delegate()
        Description copied from class: ForwardingObject
        Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.
        Specified by:
        delegate in class ForwardingObject

      • asMap

        public java.util.Map<K,​java.util.Collection<V>> asMap()
        Description copied from interface: 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.

        Specified by:
        asMap in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • 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 extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • entries

        public java.util.Collection<java.util.Map.Entry<K,​V>> entries()
        Description copied from interface: Multimap
        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.

        Specified by:
        entries in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • get

        public java.util.Collection<V> get​(K key)
        Description copied from interface: Multimap
        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.

        Specified by:
        get in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • 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 extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • keys

        public Multiset<K> keys()
        Description copied from interface: 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.

        Specified by:
        keys in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • keySet

        public java.util.Set<K> keySet()
        Description copied from interface: 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.

        Specified by:
        keySet in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • put

        @CanIgnoreReturnValue
public boolean put​(K key,
                   V value)
        Description copied from interface: Multimap
        Stores a key-value pair in this multimap.

        Some multimap implementations allow duplicate key-value pairs, in which case put always adds a new key-value pair and increases the multimap size by 1. Other implementations prohibit duplicates, and storing a key-value pair that's already in the multimap has no effect.

        Specified by:
        put in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Returns:
        true if the method increased the size of the multimap, or false if the multimap already contained the key-value pair and doesn't allow duplicates

      • putAll

        @CanIgnoreReturnValue
public boolean putAll​(K key,
                      java.lang.Iterable<? extends V> values)
        Description copied from interface: 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.

        Specified by:
        putAll in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Returns:
        true if the multimap changed

      • putAll

        @CanIgnoreReturnValue
public boolean putAll​(Multimap<? extends K,​? extends V> multimap)
        Description copied from interface: Multimap
        Stores all key-value pairs of multimap in this multimap, in the order returned by multimap.entries().
        Specified by:
        putAll in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Returns:
        true if the multimap changed

      • remove

        @CanIgnoreReturnValue
public boolean remove​(@CheckForNull
                      java.lang.Object key,
                      @CheckForNull
                      java.lang.Object value)
        Description copied from interface: 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.
        Specified by:
        remove in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Returns:
        true if the multimap changed

      • removeAll

        @CanIgnoreReturnValue
public java.util.Collection<V> removeAll​(@CheckForNull
                                         java.lang.Object key)
        Description copied from interface: Multimap
        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.

        Specified by:
        removeAll in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Returns:
        the values that were removed (possibly empty). The returned collection may be modifiable, but updating it will have no effect on the multimap.

      • replaceValues

        @CanIgnoreReturnValue
public java.util.Collection<V> replaceValues​(K key,
                                             java.lang.Iterable<? extends V> values)
        Description copied from interface: Multimap
        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).

        Specified by:
        replaceValues in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        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.

      • 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 extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • values

        public java.util.Collection<V> values()
        Description copied from interface: Multimap
        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.

        Specified by:
        values in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>

      • equals

        public boolean equals​(@CheckForNull
                      java.lang.Object object)
        Description copied from interface: 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.

        Specified by:
        equals in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Description copied from interface: Multimap
        Returns the hash code for this multimap.

        The hash code of a multimap is defined as the hash code of the map view, as returned by Multimap.asMap().

        In general, two multimaps with identical key-value mappings may or may not have the same hash codes, depending on the implementation. For example, two SetMultimap instances with the same key-value mappings will have the same hashCode, but the hashCode of ListMultimap instances depends on the ordering of the values for each key.

        Specified by:
        hashCode in interface Multimap<K extends @Nullable java.lang.Object,​V extends @Nullable java.lang.Object>
        Overrides:
        hashCode in class java.lang.Object