spinnerの挙動

Javaだな、kotlinのドキュメントが少ない気がするが、気のせいか？
https://developer.android.com/guide/topics/ui/controls/spinner?hl=ja

public void onItemSelected(AdapterView<?> parent, View view,
            int pos, long id) {
        // An item was selected. You can retrieve the selected item using
        // parent.getItemAtPosition(pos)
    }

    public void onNothingSelected(AdapterView<?> parent) {
        // Another interface callback
    }

in these two days, absolutely stunned, too much space that i have to fill in, but keep going.