putting data in Map inside map from database

Question

I have 3 columns from following query

select type, typeid, count(typeid) 
  from schema1.table_name
  where typeid is not null
  group by typeid;

I want to put output from this query into Map<String, Map<Integer, Integer>>

Data are:

type            type_id count(type_id)
Product Class   7       1
Product Class   109     2
Product Class   123     1
Product Class   132     1
SubCategory     362     3
Category        364     2
SubCategory     430     1
SubCategory     434     7
SubCategory     532     1
SubCategory     683     1
Brand           10002   10
Brand           10003   2
Brand           10393   3
Brand           12068   1

Answer 1

I’m not sure it’s the best data structure for what you’re trying to obtain. Personally I’d consider a Type class with fields type and typeId and map from this class to the count. Anyway, to answer your question, for each row from the database do:

Map<Integer, Integer> innerMap = typeIdCounts.get(type);
if (innerMap == null) {
    innerMap = new HashMap<>();
    typeIdCounts.put(product, innerMap);
}
innerMap.put(typeId, count);

Answer 2

You only need to use a Map of Maps

String type;
int type_id, count;
Map<String, Map<Integer, Integer>> data = new HashMap<>();
Map<Integer, Integer> innerMap = data.get(type);

if(innerMap == null)
{
   innerMap = new HashMap<Integer, Integer>();
   data.put(type, innerMap);
}

innerMap.put(type_id, count);