Which data type to use in java?

Question

I am actually , looking whether exist any structure or interface in java

1 -> A
1 -> B

2 -> A
2 -> B
2 -> C

which store the details as

 1 -> {A,B}  and 2 -> {A,B,C}

Like , if I use map , it might be return as

 1 -> B and 2 -> C

I am looking for something that can return as

 1 -> {A,B}  and 2 -> {A,B,C}

Thanks !

You could create a Map<Integer, Character[]> or a Map<Integer, List<Character>> or use String instead of Character, depending on your real use case. — Stephen P
– Stephen P, Commented Sep 29, 2014 at 22:24
You haven't really provided enough information about the properties of the data to answer the question. For example, are the things you've used 1 and 2 as examples for actually going to be consecutive integers? — Kevin Krumwiede
– Kevin Krumwiede, Commented Sep 29, 2014 at 22:28

Lucas · Accepted Answer · 2014-09-29 22:22:52Z

1

Like map of Arrays? You can use map to store any kind of value, you can use map of lists for example:

Map <Integer, List<YourObject> map = new HashMap<Integer, List<YourObject>;

it should work just fine in your case.

answered Sep 29, 2014 at 22:22

Lucas

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Comments

Ken Wayne VanderLinde · Accepted Answer · 2014-09-29 22:28:11Z

1

This is called a multi-map. In Java, a multi-map is easily implemented on top of a regular map, by using a collection as the value type.

Alternatively, you could use a pre-cooked multi-map implementation, say MultiMap from Apache Commons.

answered Sep 29, 2014 at 22:28

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Fermat's Little Student · Accepted Answer · 2014-09-29 22:22:54Z

0

You can use Map<Integer, List<String>> (an map whose keys are integers and values are lists of strings)

answered Sep 29, 2014 at 22:22

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