Guava Multimap – ArrayListMultimap Implementation Example – Developers Corner

Guava Multimap – ArrayListMultimap Implementation

The ArrayListMultimap is a variation of a Map in which multiple values or objects are associated with a single key but it allows duplicate key/value pairs in the Map. In this example, you will notice that the value of Amaury Valdes appears in the Multimap element with a key of 777. Notice how duplicates are allowed when I add another Amaury Valdes instance into the Map.

Methods available to ArrayListMultimap

@GwtCompatible
public interface Multimap<K,V>

#	Method and Description
1	Map<K,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.
2	void clear() Removes all key-value pairs from the multimap, leaving it empty.
3	boolean containsEntry(Object key, Object value) Returns true if this multimap contains at least one key-value pair with the key key and the value value.
4	boolean containsKey(Object keyName) Returns true if this multimap contains at least one key-value pair with the key keyName.
5	boolean containsValue(Object valueName) Returns true if this multimap contains at least one key-value pair with the value valueName.
6	Collection<Map.Entry<K,V>> entries() Returns a view collection of all key-value pairs contained in this multimap, as Map.Entry instances.
7	boolean equals(Object obj) Compares the specified object with this multimap for equality.
8	Collection<V> get(K key) Returns a view collection of the values associated with key in this multimap, if any.
9	int hashCode() Returns the hash code for this multimap.
10	boolean isEmpty() Returns true if this multimap contains no key-value pairs.
11	Multiset<K> keys() Returns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates.
12	Set<K> keySet() Returns a view collection of all distinct keys contained in this multimap.
13	boolean put(K key, V value) Stores a key-value pair in this multimap.
14	boolean putAll(K key, Iterable<? extends V> values) Stores a key-value pair in this multimap for each of values, all using the same key, key.
15	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().
16	boolean remove(Object key, Object value) Removes a single key-value pair with the key key and the value value from this multimap, if such exists.
17	Collection<V> removeAll(Object keyName) Removes all values associated with the key keyName.
18	Collection<V> replaceValues(K key, Iterable<? extends V> values) Stores a collection of values with the same key, replacing any existing values for that key.
19	int size() Returns the number of key-value pairs in this multimap.
20	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()).

Java ArrayListMultimap Example of Guava Multimap

package com.avaldes;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import com.google.common.collect.SortedSetMultimap;
import com.google.common.collect.TreeMultimap;

public class GuavaSetMultiMapExample {
  
  public static void main(String[] args) {
    Logger logger = LoggerFactory.getLogger(GuavaSetMultiMapExample.class);

    logger.info("---myArrayListMultimap----------");
    logger.info("Duplicates allowed, Not Sorted...");
    Multimap<String,String> myArrayListMultimap = ArrayListMultimap.create();
    myArrayListMultimap.put("777", "Amaury Valdes");
    myArrayListMultimap.put("777", "Walter White");
    myArrayListMultimap.put("777", "John Smith");
    myArrayListMultimap.put("777", "Eric Hamlin");
    myArrayListMultimap.put("777", "Amaury Valdes");
  }
}

Output

21:51:58.529 [main] INFO  com.avaldes.GuavaSetMultiMapExample - ---myArrayListMultimap----------
21:51:58.534 [main] INFO  com.avaldes.GuavaSetMultiMapExample - Duplicates allowed, Not Sorted...
21:51:58.543 [main] INFO  com.avaldes.GuavaSetMultiMapExample - myTreeMultimap: {777=[Amaury Valdes, Walter White, John Smith, Eric Hamlin, Amaury Valdes]}

That’s It!

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GuavaMultimapArrayList

Guava Multimap - ArrayListMultimap Implementation Example
In this tutorial we will cover implementing an ArrayListMultimap (which allows duplicate key/value pairs).
Guava Multimap - HashMultimap Implementation Example
In this tutorial we will cover implementing an HashMultimap which does not allow duplicate key/value pairs, using HashMultimap.
Guava Multimap - TreeMultimap Implementation Example
In this tutorial we will cover a implementing an TreeMultimap which performs Sorting according to natural order and does not allow duplicate key/value pairs.
Guava Multiset Example
In this tutorial we will cover a basic introduction the to Guava's Multiset collection using easy to follow example to show you how best to implement this collection in your own code.
Guava BiMap Example (Bi-Directional Map)
In this tutorial we will cover a basic introduction the to Guava's Bidirectional Map (BiMap) using easy to follow example to show you how best to implement this collection in your own code.
Guava Table Example
In this tutorial we will cover a basic introduction the to Guava's Table using easy to follow example to show you how best to implement this collection in your own code.
Guava ClassToInstanceMap Example
In this tutorial we show you how to use Guava's ClassToInstanceMap collection to store class type as the key and the instance of the collection as a value.