kwroot :
Some of you can help me with this little problem? I'm very new to Kotlin and Android development! I don't understand why this snippet of code returns me the following error:
class Catalog {
var musicList: List<Music> = ArrayList()
}
class Music{
var id: String = ""
}
fun main(args: Array<String>) {
var test: Catalog
test.musicList[0] = "1"
}
ERROR:
Variable 'test' must be initialized
What is wrong? Thank you all!
Giorgio Antonioli :
You need to instantiate it before invoking the getter of musicList:
fun main(args: Array<String>) {
var test = Catalog()
test.musicList[0] = "1"
}
Furthermore, if you are not re-assigning the value of test you can declare it as val:
fun main(args: Array<String>) {
val test = Catalog()
test.musicList[0] = "1"
}
You will have other 2 errors after that:
- since
Listis immutable so you can't use the operator[]to assign a value
To solve it, you can use MutableList instead of List.
class Catalog {
val musicList = mutableListOf<Music>()
}
- You haven't an item at index 0 so you would get an out of bounds exception. To solve it, you can add your element:
fun main(args: Array<String>) {
var test = Catalog()
test.musicList += Music("1")
}
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