Map (hashmap) with inner Map (3 values)

Question

I would like to create an object with Map<String,Map<Integer, String>> the inner should not be a Map type because the inner key (Integer) is not a primary key (unique). And as far as I know when it comes to Map if there is a similar key value it will override the previous similar data.

What should be the datatype of my inner Map?

Map> - (https://google.github.io/guava/releases/21.0/api/docs/com/google/common/collect/Multimap.html) — Meini, Nov 14 '18 at 08:49
Have a look at Guava's [Multimap](https://google.github.io/guava/releases/snapshot/api/docs/com/google/common/collect/Multimap.html) — Guy, Nov 14 '18 at 08:49

score 0 · Answer 1 · answered Nov 14 '18 at 08:50

It depends on what you are going to do with the map. If the values of the outer map are just pairs, you can use Map<String, Set<ClassContainingIntAndString>>, or if you already know what it is (like you said there are only three values?) Map<String, SomeClassThatMakesSense>. However, if you want fast access to the final Strings given the first and second Integer, you should use Map<String, Map<Integer, List<String>>> (or something similar except encapsulated in some user-defined classes, as it may be bad practice to have too many nested generics).

The first option might work, Map>> I can do this because the inner map key is not unique — SCS, Nov 14 '18 at 08:56

Map (hashmap) with inner Map (3 values)

1 Answers1