I see that Kotlin has ByteArray, ShortArray, IntArray, CharArray, DoubleArray, FloatArray, which are equivalent to byte[], short[], int[],char[], double[]
ByteArray, ShortArray, IntArray, CharArray, DoubleArray, FloatArray
byte[], short[], int[],char[], double[]
For Strings and other types, you just use Array<*>. The reason IntArray and others exist is to prevent autoboxing.
Strings
Array<*>
IntArray
So int[] relates to IntArray where Integer[] relates to Array.
int[]
Integer[]
Array