Apache Commons MultiMap is deprecated, what should I use now?

Question

Apache Commons' MultiMap interface with its MultiValueMap implementation is deprecated since version 4.1. And MultiHashMap seems to go entirely...

What should I use as an alternative?

Solution

MultiValuedMap is the replacement and it isn't deprecated:

Defines a map that holds a collection of values against each key.

For example:

 MultiValuedMap<K, String> map = new MultiValuedHashMap<K, String>();
 map.put(key, "A");
 map.put(key, "B");
 map.put(key, "C");
 Collection<String> coll = map.get(key);

It replaced MultiHashMap

Class now available as MultiValueMap in map subpackage. This version is due to be removed in collections v4.0.

and MultiValueMap:

Deprecated. since 4.1, use MultiValuedMap instead

The deprecation related to apache commons collections4 dependency jar

I think the third you meant MultiMap was deprecated

Comments

[Boris the Spider]

Just use a Map<String, Set<String>>. With the new Map methods added in Java 8 these multivalued map type things are unnecessary.

[WhiteWalker]

I used List<LinkedHashMap<String, String>> but someone told me to use MultiHashMap or its replacement for optimization. So i am confused.

[Boris the Spider]

List<Map<...>> is definitely not the same as any of the things you mention. They are Map<K, Collection<V>>.

[WhiteWalker]

So you mean MultiValuedMap won't work the same way for List<LinkedHashMap<String, String>>

[Boris the Spider]

Of course not - it's a multi valued map; it supports multiple values per key. Multiple independent maps is completely different. In your use case they may serve the same purpose, but they are definitely not the same thing.

[Mark Rotteveel]

Those classes are not part of Java itself, so they are not deprecated with any version of Java. You should specify the full qualified name of these class so we know which library they're from.

[Mark Rotteveel]

How can I check when you don't specify what classes (from which library) you are talking about? There are no classes with these names in the Java SE API, so they are not deprecated in any Java version (given they are not part of Java at all). They may be deprecated in some library, but given you give us no identifying information, we can not be sure which library.

[WhiteWalker]

(MultiValuedMap cannot be resolved to a type) is the error i am getting.

[user7294900]

@WhiteWalker you can use MultiValuedMap<String, String> map = new ArrayListValuedHashMap<>();

[WhiteWalker]

But what i have to import because its giving error as mentioned in MultiValuedMap and ArrayListValuedHashMap cannot be resolved.

[user7294900]

@WhiteWalker the commons-collections4 jar: mvnrepository.com/artifact/org.apache.commons/…