hi all, I've the following nested maps: `Map<St...

# getting-started

[Alexandru Gheorghe]

hi all, I've the following nested maps: Map<String, Map<String, Map<String, Int>>> and I'm trying to access it by nesting if statements. I am trying to increment the value (Int) to one provided as argument to a function.

In doing so, I'm encountering an issue: No set method providing array access when trying to do something like:

val keyMap = cls.parameter!!["key"] as Map<*, *>
// logic here to increment the value of the last key in the nested map
keyMap[nestedKey1][key] = new_value

the last statement is the one failing with the error shown above

my questions are:
1. how can I access nested maps in a safe manner and when I detect a key not existing, create it and nest in that if statement creating the rest of the map?
2. how can I set the map on an object (cls.parameter) such that I preserve other existing mappings and do not override with the new (and what would be the only if written) mapping?

[Alexandru Gheorghe]

Thanks. I've modified all Map< to `MutableMap<`and now I'm encountering the issue where I'm trying to access the key in order to set its value. E.g. map[key1][key2][key3] = value. In fact what I'm trying to do is Python equivalent of map[key1][key2][key3] += value. How can I achieve this value update for the innermost map and set it on a object while preserving the rest of the keys in the nested map?

[Alexandru Gheorghe]

Right! What I'm trying is map!![key1]?.get(key2) and I get an error on key2. Even though it's defined as a nested MutableMap.

[Alexandru Gheorghe]

Nevermind. Just implemented the way you coded it and it works. I have a question: what if getValue(key2) returns null? will the lambda create it? or do I have to deal with this case before calling the setting of the value?

[Alexandru Gheorghe]

I see. How to create non-existing keys in the nested mapping for each level?

[Alexandru Gheorghe]

Thanks! Will report back should I encounter any issues.

[Konstantin]

Looks like you are fighting against type system. What domain are you trying to model?
Is it some config in json/xml?
You might want to create your generic class which can hold values of different types, provides type safe access/creation/defaults and supports nesting