Kotlin - Convert Collection to Array List

Question

I'm converting a Java application to Kotlin. In one area it's using apache IO's FileUtils listFiles functions.

These return collections and I'm having problems converting/casting the collections into ArrayList

        val myFiles = FileUtils.listFiles(mediaStorageDir, extensions, true) as ArrayList<File> 

Whilst this compiles I get a runtime error as follows:

java.util.LinkedList cannot be cast to java.util.ArrayList

What's the correct way to convert a collection object into an ArrayList?

Answer 1

You can easily create ArrayList in Kotlin from any Collection

val collection = FileUtils.listFiles(mediaStorageDir, extensions, true) val arrayList = ArrayList(collection)