I'm trying to use the Android NumberPicker widget, but I can't figure out how to set a value from the NumberPicker

I'm a total noob to Kotlin and programming in general, and I want to make an app. In the app involves a NumberPicker widget. I think I got the NP set up properly, as it works when I test it, but I have no clue how to retrieve the user set value from it, and turn it into a variable/value. I think it has to do something with setOnValueChangedListener and OnvalueChangeListener but I can't figure out the syntax, let alone what each part of the syntax does. My question:

What's the syntax for initializing and retrieving values from a NumberPicker and what does each part of the syntax do?

Use OnValueChangedListener

Java:

   numberPicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
                @Override
                public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
                    String text = "Changed from " + oldVal + " to " + newVal;
                }
   });

Kotlin:

numberPicker.setOnValueChangedListener { picker, oldVal, newVal ->

            //Display the newly selected number to text view
            text_view.text = "Selected Value : $newVal"
}