how could i improve user preferences but the key values are not saved or extracted correctly?

Question

The key values you pass to save and retrieve your data in sharedpreferences are identical… each is an empty string

“”

const val UNIT = ""
const val VOLUME = ""
const val HEIGHT = ""
const val CALCULATION = ""

Each key must be unique and contain an actual string value that can be retrieved against:

const val UNIT = "UNIT"
const val VOLUME = "VOLUME"
const val HEIGHT = "HEIGHT"
const val CALCULATION = "CALCULATION"

Since the values retrieved are integers not strings then why not store them as integers?

pref.getInt(UNIT, 0)

editor.putInt(UNIT, outputUnit.text.toString().toInt())