Question

I got a string with the following format : yyyyMMdd_HHmm_ss_unitCode_(status).
I need to map each component to a property of a dedicated class.

I thought of defining my token with a regular expression like this :
{d+}4{d+}2{d+}2_{d+}2_{d+}2_{s+}3_{s+}2 => Apologize for the approximate regex syntax, d is for decimal and s for string.

How can I tell my parser that the first group {d+}4 must go in the “year” property of my class, the second to the “month” and so forth.

Obviously, I could just do this : token.setYear(substring(0,4)) but I wanted to be a little more generic since I do not have control over the structure of the filename.
I also considered defining an xml structure with startPosition, endPosition, attribute name to store and type.

All in all, I thought all of this much too complicated. The problem is that I do not have a single separator to enable me to use a String.split.

Answer 1

String input; // yyyyMMdd_HHmm_ss_unitCode_(status)
SpecialClass output;

String regex = "(\\d{4})(\\d{2})(\\d{2})_(\\d{2})(\\d{2})_(\\d{2})_([^_]+)_\\((.+)\\)";
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(input);

if (m.matches())
{
    output.year = m.group(1);
    output.month = m.group(2);
    // etc
}

Example input:

String input = "20120113_1234_27_500_(33)";

Will produce the following groups:

Group 1: 2012 //year
Group 2: 01   //month
Group 3: 13   //day
Group 4: 12   //hour
Group 5: 34   //minute
Group 6: 27   //second
Group 7: 500  //unitcode
Group 8: 33   //status

Test program: http://pastebin.com/upC5R9rP