parse JSON double to Double (null allowed), catching optional NumberFormatException

gistfile1.java

    public static Double parseDouble(String string) throws ParseException {
        if("null".equals(string)) {
            return null;
        }

        try {
            return Double.parseDouble(string);
        } catch (NumberFormatException e) {
            throw new ParseException("Unparseable double: " + string, 0);
        }
    }