private void setMaxDigits(int timeUnits) {
            if (timeUnits == TimeDurationPicker.HH_MM_SS)
                maxDigits = 6;
            else
                maxDigits = 4;
            setDuration(duration);
        }
Encapsulates the digit input logic and text to duration conversion logic.
android/third_party/time-duration-picker/src/main/java/mobi/upod/timedurationpicker/TimeDurationPicker.java