com.google.common.collect
Class ImmutableMultimap<K,V>

java.lang.Object
  com.google.common.collect.ImmutableMultimap<K,V>

All Implemented Interfaces:

Multimap<K,V>, Serializable

Direct Known Subclasses:

ImmutableListMultimap, ImmutableSetMultimap

@GwtCompatible(emulated=true)
public abstract class ImmutableMultimap<K,V>
extends Object
implements Multimap<K,V>, Serializable

An immutable Multimap. Does not permit null keys or values.

Unlike Multimaps.unmodifiableMultimap(Multimap), which is a view of a separate multimap which can still change, an instance of ImmutableMultimap contains its own data and will never change. ImmutableMultimap is convenient for public static final multimaps ("constant multimaps") and also lets you easily make a "defensive copy" of a multimap provided to your class by a caller.

Note: Although this class is not final, it cannot be subclassed as it has no public or protected constructors. Thus, instances of this class are guaranteed to be immutable.

Since:

2 (imported from Google Collections Library)

Author:

Jared Levy

See Also:

Serialized Form

of

public static <K,V> ImmutableMultimap<K,V> of()

Returns an empty multimap.

of

public static <K,V> ImmutableMultimap<K,V> of(K k1,
                                              V v1)

Returns an immutable multimap containing a single entry.

of

public static <K,V> ImmutableMultimap<K,V> of(K k1,
                                              V v1,
                                              K k2,
                                              V v2)

Returns an immutable multimap containing the given entries, in order.

of

public static <K,V> ImmutableMultimap<K,V> of(K k1,
                                              V v1,
                                              K k2,
                                              V v2,
                                              K k3,
                                              V v3)

Returns an immutable multimap containing the given entries, in order.

of

public static <K,V> ImmutableMultimap<K,V> of(K k1,
                                              V v1,
                                              K k2,
                                              V v2,
                                              K k3,
                                              V v3,
                                              K k4,
                                              V v4)

Returns an immutable multimap containing the given entries, in order.

of

public static <K,V> ImmutableMultimap<K,V> of(K k1,
                                              V v1,
                                              K k2,
                                              V v2,
                                              K k3,
                                              V v3,
                                              K k4,
                                              V v4,
                                              K k5,
                                              V v5)

Returns an immutable multimap containing the given entries, in order.

builder

public static <K,V> ImmutableMultimap.Builder<K,V> builder()

Returns a new builder. The generated builder is equivalent to the builder created by the ImmutableMultimap.Builder constructor.

copyOf

public static <K,V> ImmutableMultimap<K,V> copyOf(Multimap<? extends K,? extends V> multimap)

Returns an immutable multimap containing the same mappings as multimap. The generated multimap's key and value orderings correspond to the iteration ordering of the multimap.asMap() view.

Despite the method name, this method attempts to avoid actually copying the data when it is safe to do so. The exact circumstances under which a copy will or will not be performed are undocumented and subject to change.

Throws:

NullPointerException - if any key or value in multimap is null

removeAll

public ImmutableCollection<V> removeAll(Object key)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

removeAll in interface Multimap<K,V>

Parameters:

key - key of entries to remove from the multimap

Returns:

the collection of removed values, or an empty collection if no values were associated with the provided key. The collection may be modifiable, but updating it will have no effect on the multimap.

Throws:

UnsupportedOperationException - always

replaceValues

public ImmutableCollection<V> replaceValues(K key,
                                            Iterable<? extends V> values)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

replaceValues in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

values - values to store in the multimap

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.

Throws:

UnsupportedOperationException - always

clear

public void clear()

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

clear in interface Multimap<K,V>

Throws:

UnsupportedOperationException - always

get

public abstract ImmutableCollection<V> get(K key)

Returns an immutable collection of the values for the given key. If no mappings in the multimap have the provided key, an empty immutable collection is returned. The values are in the same order as the parameters used to build this multimap.

Specified by:

get in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

Returns:

the collection of values that the key maps to

put

public boolean put(K key,
                   V value)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

put in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

value - value to store in the multimap

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

Throws:

UnsupportedOperationException - always

putAll

public boolean putAll(K key,
                      Iterable<? extends V> values)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

putAll in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

values - values to store in the multimap

Returns:

true if the multimap changed

Throws:

UnsupportedOperationException - always

putAll

public boolean putAll(Multimap<? extends K,? extends V> multimap)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

putAll in interface Multimap<K,V>

Parameters:

multimap - mappings to store in this multimap

Returns:

true if the multimap changed

Throws:

UnsupportedOperationException - always

remove

public boolean remove(Object key,
                      Object value)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

remove in interface Multimap<K,V>

Parameters:

key - key of entry to remove from the multimap

value - value of entry to remove the multimap

Returns:

true if the multimap changed

Throws:

UnsupportedOperationException - always

containsEntry

public boolean containsEntry(@Nullable
                             Object key,
                             @Nullable
                             Object value)

Description copied from interface: Multimap

Returns true if the multimap contains the specified key-value pair.

Specified by:

containsEntry in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

value - value to search for in multimap

containsKey

public boolean containsKey(@Nullable
                           Object key)

Description copied from interface: Multimap

Returns true if the multimap contains any values for the specified key.

Specified by:

containsKey in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

containsValue

public boolean containsValue(@Nullable
                             Object value)

Description copied from interface: Multimap

Returns true if the multimap contains the specified value for any key.

Specified by:

containsValue in interface Multimap<K,V>

Parameters:

value - value to search for in multimap

isEmpty

public boolean isEmpty()

Description copied from interface: Multimap

Returns true if the multimap contains no key-value pairs.

Specified by:

isEmpty in interface Multimap<K,V>

size

public int size()

Description copied from interface: Multimap

Returns the number of key-value pairs in the multimap.

Specified by:

size in interface Multimap<K,V>

equals

public boolean equals(@Nullable
                      Object object)

Description copied from class: java.lang.Object

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.

Specified by:

equals in interface Multimap<K,V>

Overrides:

equals in class Object

Parameters:

object - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

See Also:

Object.hashCode(), Hashtable

hashCode

public int hashCode()

Description copied from class: java.lang.Object

Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.

As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the Java^TM programming language.)

Specified by:

hashCode in interface Multimap<K,V>

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable

toString

public String toString()

Description copied from class: java.lang.Object

Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 

Overrides:

toString in class Object

Returns:

a string representation of the object.

keySet

public ImmutableSet<K> keySet()

Returns an immutable set of the distinct keys in this multimap. These keys are ordered according to when they first appeared during the construction of this multimap.

Specified by:

keySet in interface Multimap<K,V>

Returns:

the collection of distinct keys

asMap

public ImmutableMap<K,Collection<V>> asMap()

Returns an immutable map that associates each key with its corresponding values in the multimap.

Specified by:

asMap in interface Multimap<K,V>

Returns:

a map view from a key to its collection of values

entries

public ImmutableCollection<Map.Entry<K,V>> entries()

Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses the values for the first key, the values for the second key, and so on.

Specified by:

entries in interface Multimap<K,V>

Returns:

collection of map entries consisting of key-value pairs

keys

public ImmutableMultiset<K> keys()

Returns a collection, which may contain duplicates, of all keys. The number of times a key appears in the returned multiset equals the number of mappings the key has in the multimap. Duplicate keys appear consecutively in the multiset's iteration order.

Specified by:

keys in interface Multimap<K,V>

Returns:

a multiset with keys corresponding to the distinct keys of the multimap and frequencies corresponding to the number of values that each key maps to

values

public ImmutableCollection<V> values()

Returns an immutable collection of the values in this multimap. Its iterator traverses the values for the first key, the values for the second key, and so on.

Specified by:

values in interface Multimap<K,V>

Returns:

collection of values, which may include the same value multiple times if it occurs in multiple mappings