com.google.common.collect

Class MultimapBuilder<K0,V0>

java.lang.Object

com.google.common.collect.MultimapBuilder<K0,V0>

Type Parameters:

K0 - An upper bound on the key type of the generated multimap.

V0 - An upper bound on the value type of the generated multimap.

Direct Known Subclasses:

MultimapBuilder.ListMultimapBuilder, MultimapBuilder.SetMultimapBuilder

@Beta
@GwtCompatible
public abstract class MultimapBuilder<K0,V0>
extends Object

A builder for a multimap implementation that allows customization of the backing map and value collection implementations used in a particular multimap.

This can be used to easily configure multimap data structure implementations not provided explicitly in com.google.common.collect, for example:

   ListMultimap<String, Integer> treeListMultimap =
       MultimapBuilder.treeKeys().arrayListValues().build();
   SetMultimap<Integer, MyEnum> hashEnumMultimap =
       MultimapBuilder.hashKeys().enumSetValues(MyEnum.class).build();

MultimapBuilder instances are immutable. Invoking a configuration method has no effect on the receiving instance; you must store and use the new builder instance it returns instead.

The generated multimaps are serializable if the key and value types are serializable, unless stated otherwise in one of the configuration methods.

Since:

16.0

Author:

Louis Wasserman

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MultimapBuilder.ListMultimapBuilder<K0,V0> A specialization of MultimapBuilder that generates ListMultimap instances.
static class	MultimapBuilder.MultimapBuilderWithKeys<K0> An intermediate stage in a MultimapBuilder in which the key-value collection map implementation has been specified, but the value collection implementation has not.
static class	MultimapBuilder.SetMultimapBuilder<K0,V0> A specialization of MultimapBuilder that generates SetMultimap instances.
static class	MultimapBuilder.SortedSetMultimapBuilder<K0,V0> A specialization of MultimapBuilder that generates SortedSetMultimap instances.

Method Summary

Methods

Modifier and Type	Method and Description
abstract <K extends K0,V extends V0> Multimap<K,V>	build() Returns a new, empty Multimap with the specified implementation.
<K extends K0,V extends V0> Multimap<K,V>	build(Multimap<? extends K,? extends V> multimap) Returns a Multimap with the specified implementation, initialized with the entries of multimap.
static <K0 extends Enum<K0>> MultimapBuilder.MultimapBuilderWithKeys<K0>	enumKeys(Class<K0> keyClass) Uses an EnumMap to map keys to value collections.
static MultimapBuilder.MultimapBuilderWithKeys<Object>	hashKeys() Uses a HashMap to map keys to value collections.
static MultimapBuilder.MultimapBuilderWithKeys<Object>	hashKeys(int expectedKeys) Uses a HashMap to map keys to value collections, initialized to expect the specified number of keys.
static MultimapBuilder.MultimapBuilderWithKeys<Object>	linkedHashKeys() Uses a LinkedHashMap to map keys to value collections.
static MultimapBuilder.MultimapBuilderWithKeys<Object>	linkedHashKeys(int expectedKeys) Uses a LinkedHashMap to map keys to value collections, initialized to expect the specified number of keys.
static MultimapBuilder.MultimapBuilderWithKeys<Comparable>	treeKeys() Uses a naturally-ordered TreeMap to map keys to value collections.
static <K0> MultimapBuilder.MultimapBuilderWithKeys<K0>	treeKeys(Comparator<K0> comparator) Uses a TreeMap sorted by the specified comparator to map keys to value collections.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

hashKeys

public static MultimapBuilder.MultimapBuilderWithKeys<Object> hashKeys()

Uses a HashMap to map keys to value collections.

hashKeys

public static MultimapBuilder.MultimapBuilderWithKeys<Object> hashKeys(int expectedKeys)

Uses a HashMap to map keys to value collections, initialized to expect the specified number of keys.

Throws:

IllegalArgumentException - if expectedKeys < 0

linkedHashKeys

public static MultimapBuilder.MultimapBuilderWithKeys<Object> linkedHashKeys()

Uses a LinkedHashMap to map keys to value collections.

The collections returned by Multimap.keySet(), Multimap.keys(), and Multimap.asMap() will iterate through the keys in the order that they were first added to the multimap, save that if all values associated with a key are removed and then the key is added back into the multimap, that key will come last in the key iteration order.

linkedHashKeys

public static MultimapBuilder.MultimapBuilderWithKeys<Object> linkedHashKeys(int expectedKeys)

Uses a LinkedHashMap to map keys to value collections, initialized to expect the specified number of keys.

The collections returned by Multimap.keySet(), Multimap.keys(), and Multimap.asMap() will iterate through the keys in the order that they were first added to the multimap, save that if all values associated with a key are removed and then the key is added back into the multimap, that key will come last in the key iteration order.

treeKeys

public static MultimapBuilder.MultimapBuilderWithKeys<Comparable> treeKeys()

Uses a naturally-ordered TreeMap to map keys to value collections.

The collections returned by Multimap.keySet(), Multimap.keys(), and Multimap.asMap() will iterate through the keys in sorted order.

For all multimaps generated by the resulting builder, the Multimap.keySet() can be safely cast to a SortedSet, and the Multimap.asMap() can safely be cast to a SortedMap.

treeKeys

public static <K0> MultimapBuilder.MultimapBuilderWithKeys<K0> treeKeys(Comparator<K0> comparator)

Uses a TreeMap sorted by the specified comparator to map keys to value collections.

The collections returned by Multimap.keySet(), Multimap.keys(), and Multimap.asMap() will iterate through the keys in sorted order.

For all multimaps generated by the resulting builder, the Multimap.keySet() can be safely cast to a SortedSet, and the Multimap.asMap() can safely be cast to a SortedMap.

Multimaps generated by the resulting builder will not be serializable if comparator is not serializable.

enumKeys

public static <K0 extends Enum<K0>> MultimapBuilder.MultimapBuilderWithKeys<K0> enumKeys(Class<K0> keyClass)

Uses an EnumMap to map keys to value collections.

build

public abstract <K extends K0,V extends V0> Multimap<K,V> build()

Returns a new, empty Multimap with the specified implementation.

build

public <K extends K0,V extends V0> Multimap<K,V> build(Multimap<? extends K,? extends V> multimap)

Returns a Multimap with the specified implementation, initialized with the entries of multimap.