How can I create a Multimap in Java on Android

Question

Where can I find an implementation of multimap for Java that will work on Android without having to include any other classes etc. The implementations I\'ve found all requir

Answer 1

It looks like you are looking for Apache Commons Collection library. There you have a MultiMap class. I haven't tested it myself yet so I can't promise it works but it just looks about right for your project.

You won't find a MultiMap function in Java hence others have written libraries containing it. You can however try to implement it yourself if you're knowledge-level is high enough but that'd require some Java experience. So your best bet is to try to learn how to use and if necessary adapt libraries for using them on Android.

Answer 2

You could use a Map and a List to create a multimap. Say you wanted to associate an integer with a list of class type T. Use the following code:

Map<Integer, List<T>> myMultiMap = new HashMap<Integer, List<T>>();

It could get messy but, this should give you what you're looking for.

Another option is to use the Guava library's Multimap implementations.

Answer 3

If you care about code size, we just added multimaps to our utility library: http://greenrobot.org/2015/12/11/multimaps-in-greenrobot-common-2-2/

The jar is way below 100k, which is nice if you consider Android's 65K method limit.