Issue
I have been working mainly in JAVA but now I need to program some small things in kotlin. Among other things I am trying to convert the result of a database query into a list of array. The result of the database query has 4 columns, the number of rows I can not predict.
I have tried the following:
var output: mutableList<List<String>>
var output = mutableListOf<String>()
var output = mutableListOf<ArrayList>
List<List<String>> listOfLists = new ArrayList<List<String>>()
What I would like to do is this:
output.add(arrayOf("Field1", "Filed2", "Field3", "Field4"))
It can't be that hard, can it?
Solution
In kotlin you should use lists where you can. What you are trying to create is:
val output = mutableListOf<List<String>>()
output.add(listOf("Field1", "Filed2", "Field3", "Field4"))
If you are iterating through some other list to create your data for output you could do something like:
val otherList = listOf<String>("a", "b", "v")
val output = otherList.map { otherListData ->
listOf(otherListData + 1, otherListData + 2, otherListData + 3, otherListData + 4)
}
In which case you would only have immutable lists.
Answered By - Милош Којадиновић
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