Question

Consider that you have the following string:

id: 1 name: Joe age: 27 id: 2 name: Mary age:22

And you want to extract every token after “age:” BUT NOT the string “age:” itself.

So I want my Matcher‘s group() to return 27 and 22 and not “age: 27” and “age:22”

Is there a way to specify this instruction in the Java Regex syntax, which seems quite different than that in Perl, where I learned my Regex basics?

This is my code:

import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class RegExTest 
{
    public static void main(String[] args) 
    {
        Pattern namePtrn = Pattern.compile("age: *\\w*");

        String data = "id: 1 name: Joe age:27 id: 2 name: Mary age:22";

        Matcher nameMtchr = namePtrn.matcher(data);

        while(nameMtchr.find())
        {
            String find = nameMtchr.group();

            System.out.println ("\t" + find);
        }
    }
}

In Perl I can use {} to limit the portion of the pattern that I want extracted

while($text =~ m/(age:{\w+})/g)
{
      my $find = $1;

      if($find)
      {
          print "\nFIND = ".$find;
      }
}

would return

FIND = 27
FIND = 22

and if I put {} around age like

while($text =~ m/({age:\w+})/g)

it would return

FIND = age: 27
FIND = age:22

So I am looking for something like Perl’s {} but in Java.

Answer 1

If you use Matcher.group(1) instead of Matcher.group() you can capture the pattern minus ‘age:’:

String data = "id: 1 name: Joe age:27 id: 2 name: Mary age:22";
Pattern namePtrn = Pattern.compile("age:(\\w+)");
Matcher nameMtchr = namePtrn.matcher(data);

while (nameMtchr.find()) {
   String find = nameMtchr.group(1);
   System.out.println("\t" + find);
}