Map Inside Map In Java: There are only 2 type parameters to a map. You are calling gens.put (string, string) and should instead be. As already shown explained one might do it like this.
Map Inside Map In Java
The only difference between a hashmap and a nested hashmap is: Gens is mapping string to hashmap. Yes, you can do it.
Map Inside Map In Java: Gens is mapping string to hashmap. Web a nested hashmap is map inside a map. Web a map<k,v> is a mapping from keys of type k to values of type v.