Java Regular Expression Matching for hh:mm:ss in String

Question

I am parsing a file and it has time based entries in it. format is like:

00:02:10-XYZ:Count=10
00:04:50-LMK:Count=3

Here what I want is to extract the time value from string line

I have searched many links and couldn't find out the thing what I want, eventually I have written this code.

    Pattern pattern = Pattern.compile("((?i)[0-9]{1,2}:??[0-9]{0,2}:??[0-9]{0,2})"); //(?i)[0-9]{1,2}:??[0-9]{0,2}:??[0-9]{0,2}  //\\d{1,2}:\\d{1,2}:\\d{1,2}
    Matcher matcher;
    List<String> listMatches;

Below is the loop where I apply logic

    for(int x = 0; x < file_content.size(); x++)
    {
            matcher= pattern.matcher(file_content.get(x));
            listMatches = new ArrayList<String>();
            while(matcher.find())
            {
                listMatches.add(matcher.group(1));
                break;
            }
     }

I want when "matcher.find()" gives true it returns me [00:02:10] in first iteration and [00:04:50] in 2nd iterations.

Answer 1

Seems like an unnecessarily complicated pattern.... why not just (if you are doing line-by-line processing):

"^(\\d\\d:\\d\\d:\\d\\d)"

If you are doing multi-line processing you will want to use:

"(?m)^(\\d\\d:\\d\\d:\\d\\d)"

Here's some example code and output:

public static void main(String[] args) {
    final Pattern pattern = Pattern.compile("(?m)^(\\d\\d:\\d\\d:\\d\\d)");
    final Matcher matcher = pattern.matcher("00:02:10-XYZ:Count=10\n00:04:50-LMK:Count=3");
    while(matcher.find())
    {
        System.out.printf("[%s]\n", matcher.group(1));
    }        
}

outputs

[00:02:10]
[00:04:50]