HackerRank Java- Tag Content Extractor

Given a string of text in a tag-based language, parse this text and retrieve the contents enclosed within sequences of well-organized tags meeting the following criterion:

The name of the start and end tags must be same. The HTML code

Hello World

is not valid, because the text starts with an h1 tag and ends with a non-matching h2 tag.

Tags can be nested, but content between nested tags is considered not valid. For example, in

contentsinvalid

, contents is valid but invalid is not valid.

Tags can consist of any printable characters.

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution{
	public static void main(String[] args){
		
		Pattern r = Pattern.compile("<(.+?)>([^<>]+)</\\1>");
        Scanner in = new Scanner(System.in);
        int testCases = Integer.parseInt(in.nextLine());

        while (testCases-- > 0) {
            String line = in.nextLine();
            Matcher m = r.matcher(line);

            boolean invalid = true;
            while (m.find()) {
                System.out.println(m.group(2));
                invalid = false;
            }
            if (invalid)
                System.out.println("None");
        }
    }
}