private boolean isDigitBetweenOneAndFour(String str)
    {
        boolean isDigitAppropriate = false;
        char[] signsInString = str.toCharArray();
        if (signsInString.length == 1)
        {
            char sign = signsInString[0];
            isDigitAppropriate = Character.isDigit(sign) && Character.getNumericValue(sign) > 0 &&  Character.getNumericValue(sign) < 5;
        }
        return isDigitAppropriate;
    }