How to use java regex to match a line

Question

The raw data is:

auser1 home1b auser2 home2b auser3 home3b 

I want to match a line, but it doesn't work using ^(.*?)$

However, I can use a(.*?)b to match user1 home1.

How can I match auser1 home1b

Answer 1

By default, ^ and $ match the start- and end-of-input respectively. You'll need to enable MULTI-LINE mode with (?m), which causes ^ and $ to match the start- and end-of-line:

(?m)^.*$ 

The demo:

import java.util.regex.*;  public class Main {     public static void main(String[] args) throws Exception {          String text = "auser1 home1b\n" +                 "auser2 home2b\n" +                 "auser3 home3b";          Matcher m = Pattern.compile("(?m)^.*$").matcher(text);          while (m.find()) {             System.out.println("line = " + m.group());         }     } } 

produces the following output:

line = auser1 home1b line = auser2 home2b line = auser3 home3b

EDIT I

The fact that ^.*$ didn't match anything is because the . by default doesn't match \r and \n. If you enable DOT-ALL with (?s), causing the . to match those as well, you'll see the entire input string being matched:

(?s)^.*$ 

EDIT II

In this case, you mind as well drop the ^ and $ and simply look for the pattern .*. Since . will not match \n, you'll end up with the same matches when looking for (?m)^.*$, as @Kobi rightfully mentioned in the comments.