Find duplicate words RegExp

DuplicateWords.java

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

public class DuplicateWords {
  /*
  https://rubular.com/r/98MZ0vzUeX
  \b : Any word boundary (\w+) : Select any word character (letter, number, underscore)
  
  (   : Grouping starts  
  \b  : Any word boundary
  \W+ : Any non-word character
  \1  : Select repeated words
  \b  : Un select if it repeated word is joined with another word
   )  : Grouping ends
  */
    public static void main(String[] args) {

        String regex = "\\b(\\w+)(\\b\\W+\\1\\b)*";
        Pattern p = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);

        Scanner in = new Scanner(System.in);
        int numSentences = Integer.parseInt(in.nextLine());
        
        while (numSentences-- > 0) {
            String input = in.nextLine();
            
            Matcher m = p.matcher(input);
            
            // Check for subsequences of input that match the compiled pattern
            while (m.find()) {
                input = input.replaceAll(m.group(), m.group(1));
            }
            
            // Prints the modified sentence.
            System.out.println(input);
        }
        
        in.close();
    }
}