Extracting Strings with RegEx in Salesforce Apex

Hey everyone. This is just another quick tip type of deal. It’s pretty easy to replace strings with Apex and regular expressions, but it’s a little bit harder to extract that string. In this example I want to extract a project number from an email subject line. The project number will be between { } braces. So how exactly do I got about doing this? Well it looks a bit like this.

string subject = 'this is a test {12312-D} email subject [dfasdfa]';
Pattern p = Pattern.compile('\\{([^}]*)\\}');
Matcher m = p.matcher(subject);
if (m.find()) 
{
   system.debug(m.group(1)); 
}

First I create a string to search. then I create matching pattern by using the pattern class and my nifty little regular expression. Remember to use Java style regular expressions! then I do a match against the subject line. After that I want to check and see if there was a match, and if so I debug out the first grouping. the 0th grouping contains the match with the brackets, and the 1st contains the text without. So there you have it. Just modify the regular expression to suit your needs and you should be on your way. Have fun!