Regular expression in Java for parsing money

Question

I'm looking for are regex for parsing money amounts. The String s10 should not match. Can someone help, or can someone simplify the regex? That's my try:

    public static String[] getMoney(String s) {
        List<String> ret = new ArrayList<String>();
        String regex = "((\\d{1,3}[.,]?)(\\d{3}[.,]?)*[.,]\\d{1,2})(\\D|$)";
        Pattern pat = Pattern.compile(regex);
        Matcher mat = pat.matcher(s);
        while (mat.find()) {
            ret.add(mat.group(1));
        }
        return ret.toArray(new String[0]);
    }

    public static void main(String[] args) {
        String s1 = "0,1"; // should match
        String s2 = ",1"; // should not match
        String s3 = "1,"; // should not match
        String s4 = "1.234,01"; // should match
        String s5 = "1234,10"; // should match
        String s6 = "1234,100"; // should not match
        String s7 = "1234,10a"; // should match
        String s8 = "123,456,789.10"; // should match
        String s9 = "123.456.789,10"; // should match
        String s10 = "123,456.789,10"; // should not match (!)

        System.out.println(Arrays.toString(getMoney(s1)));
        System.out.println(Arrays.toString(getMoney(s2)));
        System.out.println(Arrays.toString(getMoney(s3)));
        System.out.println(Arrays.toString(getMoney(s4)));
        System.out.println(Arrays.toString(getMoney(s5)));
        System.out.println(Arrays.toString(getMoney(s6)));
        System.out.println(Arrays.toString(getMoney(s7)));
        System.out.println(Arrays.toString(getMoney(s8)));
        System.out.println(Arrays.toString(getMoney(s9)));
        System.out.println(Arrays.toString(getMoney(s10)));
    }

Does this https://stackoverflow.com/questions/16148034/regex-for-number-with-decimals-and-thousand-separator solve your problem? (possible duplicate) — hradecek, Jun 13 '20 at 19:34
@ikos23 Because there is a String, that contains a valid amount of money. — unknown_dcba, Jun 13 '20 at 19:40
So, you do not want to match a number without a fractional part, right? The two digits after a decimal separator must be present? — Wiktor Stribiżew, Jun 13 '20 at 19:41
@hradecek The regex from Loamhoof's answer only matches point separated values... — unknown_dcba, Jun 13 '20 at 19:44
@WiktorStribiżew Only a point or a semicolon as fractional part separator should must be present. — unknown_dcba, Jun 13 '20 at 19:46
Do you want to match `String s11 = "50";`? `String s12 = "50000";`? `String s13 = "1234,1";` — Wiktor Stribiżew, Jun 13 '20 at 19:52
Do you HAVE to use a regex? If this is for work, you may want to use an actual parser, e.g. coming from a library like Joda-Money: https://www.joda.org/joda-money/ — Petr Janeček, Jun 13 '20 at 20:25

score 1 · Accepted Answer · answered Jun 13 '20 at 20:14

I think you may use

(?<![\d,.])(?:\d{1,3}(?:(?=([.,]))(?:\1\d{3})*)?|\d+)(?:(?!\1)[.,]\d{1,2})?(?![,.\d])

See the regex demo

Details

(?<![\d,.]) - no digit, . or , allowed immediately on the left
(?:\d{1,3}(?:(?=([.,]))(?:\1\d{3})*)?|\d+) -
- \d{1,3}(?:(?=([.,]))(?:\1\d{3})*)? - one, two or three digits followed with an optional occurrence of a position followed with a comma or dot followed with 0 or more occurrences of the captured value and then any three digits
- |\d+ - or 1 or more digits
(?:(?!\1)[.,]\d{1,2})? - an optional sequence of a comma or dot, but not the same char as in Group 1, and then 1 or 2 digits
(?![,.\d]) - no digit, . or , allowed immediately on the right

In Java, do not forget to double the backslashes:

String regex = "(?<![\\d,.])(?:\\d{1,3}(?:(?=([.,]))(?:\\1\\d{3})*)?|\\d+)(?:(?!\\1)[.,]\\d{1,2})?(?![,.\\d])";

Thank you Wiktor Stribiżew, i have to understand that, because it's not immediately understandable for me, and than that could be the solution. — unknown_dcba, Jun 18 '20 at 14:20

Regular expression in Java for parsing money

1 Answers1