Question

I have two regular expressions, one pulling out usernames from a csv string, and the other pulling out emails.

the string format is like this:

String s = "name lastname (username) <[e-mail]>; name lastname (username) <[e-mail]>; name lastname (username) <[e-mail]>";

the code for my regular expressions are like this.

Pattern pattern = Pattern.compile("(?<=\\()[^\\)]+");
Matcher matcher = pattern.matcher(s);
Pattern pattern2 = Pattern.compile("((?<=<)[^>]+)");
Matcher matcher2 = pattern2.matcher(s);

while (matcher.find() && matcher2.find()) {
    System.out.println(matcher.group() + " " + matcher2.group());
}

I’ve found several qeustions about merging regexes, but from the answers i haven’t been able to figure out how to merge mine.

my printouts show:

"username [e-mail]"

would I be able to print out the same from a single matcher, using one regex?

obs: this is a school assignment, which means i do not “need” to merge them or do any more, but i’d like to know if it is possible, and how difficult it would be.

Answer 1

You can just use an Pipe (|) in between your multiple Regex, to match all of them : –

    String s = "name lastname (username) <[e-mail]>; name lastname
            (username) <[e-mail]>; name lastname 
            (username) <[e-mail]>;";

    // Matches (?<=\\()[^\\)]+  or  ((?<=<)[^>]+)
    Pattern pattern = Pattern.compile("(?<=\\()[^\\)]+|((?<=<)[^>]+)");
    Matcher matcher = pattern.matcher(s);

    while (matcher.find()) {
        System.out.println(matcher.group());
    }

OUTPUT: –

username
[e-mail]
username
[e-mail]
username
[e-mail]

UPDATE: –

If you want to print username and email only when they both exists, then you need to split your string on ; and then apply the below Regex on each of them.

Here’s the code: –

    String s = "name lastname (username) ; 
                name lastname (username) <[e-mail]>; 
                name lastname (username) <[e-mail]>;";

    String [] strArr = s.split(";");

    for (String str: strArr) {

        Pattern pattern = Pattern.compile("\\(([^\\)]+)(?:\\))\\s(?:\\<)((?<=<)[^>]+)");
        Matcher matcher = pattern.matcher(str);

        while (matcher.find()) {
            System.out.print(matcher.group(1) + " " + matcher.group(2));
        }
        System.out.println();
    }

OUTPUT: –

username [e-mail]
username [e-mail] // Only the last two have both username and email