这是因为num是Char，即结果值是该char的ascii值.

That's because num is a Char, i.e. the resulting values are the ascii value of that char.

这可以解决问题:

val txt = "82389235"
val numbers = txt.map { it.toString().toInt() }

map可以进一步简化:

map(Character::getNumericValue)