Android NumberPicker with Formatter doesn't format on first rendering

I have a NumberPicker that has a formatter that formats the displayed numbers either when the NumberPicker spins or when a value is entered manually. This works fine, but when the NumberPicker is first shown and I initialize it with setValue(0) the 0 does not get formatted (it should display as "-" instead of 0). As soon as I spin the NumberPicker from that point on everything works.

How can I force the NumberPicker to format always - Both on first rendering and also when I enter a number manually with the keyboard?

This is my formatter

public class PickerFormatter implements Formatter {

 private String mSingle;
 private String mMultiple;

 public PickerFormatter(String single, String multiple) {
    mSingle = single;
    mMultiple = multiple;
 }

 @Override
 public String format(int num) {
    if (num == 0) {
        return "-";
    }
    if (num == 1) {
        return num + " " + mSingle;
    }
    return num + " " + mMultiple;
 }

}

I add my formatter to the picker with setFormatter(), this is all I do to the picker.

    picker.setMaxValue(max);
    picker.setMinValue(min);
    picker.setFormatter(new PickerFormatter(single, multiple));
    picker.setWrapSelectorWheel(wrap);

Kotlin version based on Nikolai's answer

private fun initNumberPicker() {
    nrPicker.children.iterator().forEach {
        if (it is EditText) it.filters = arrayOfNulls(0)    // remove default input filter
    }
}