How to get array of strings from Map<String, Any?> in kotlin?

Question

I read a yaml file to a map in kotlin (Map<String, Any>) this yaml file contains a list of strings, eks:

...
myStrings:
  - string1
  - string2
  - string3
...

I read the map as follows:

private fun readWithGson(jsonPath: String): Map<String, Any> {
    val bufferedReader = BufferedReader(FileReader(jsonPath))
    val gson = Gson()

    @Suppress("UNCHECKED_CAST")
    return gson.fromJson(bufferedReader, Map::class.java) as Map<String, Any>
}

When println(map), it contains:

...
myStrings=[string1,string2,string3]
...

How can get the array of strings?

map["myStrings"] as Array<String>

produces a java.lang.ClassCastException

Use .toTypedArray(). Using as is for casting, not converting. — Tenfour04
– Tenfour04, Commented Oct 28, 2020 at 16:14
You've edited the question and suddenly the results are entire different than last time. What stands out is that you are using Gson, which expects a JSON format to parse a yaml file.. Not sure how that even works but you'll likely need a yaml parser like snakeYAML — RobCo
– RobCo, Commented Oct 29, 2020 at 9:18
I am sorry for editing the question... The provided answer did work. I noticed I had some code which was not changed, when I allready had started to edit the question... I forgot all about it... :( — jactor-rises
– jactor-rises, Commented Oct 30, 2020 at 11:00

RobCo · Accepted Answer · 2020-10-28 16:21:47Z

1

It is stored as an (Array)List. So just get and use it as a List:

val myStrings = map["myStrings"] as List<String>

If you need to edit the list later on you can cast it to MutableList:

val myStrings = map["myStrings"] as MutableList<String>

If you really need it to be an Array, though for most cases you don't, you'll have to convert the List to an array:

val myStringsArray = myStrings.toTypedArray()

answered Oct 28, 2020 at 16:21

RobCo

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