Regex: Replace <a> Tag

/*
    You are given an HTML document given as a string on multiple lines.
    Write a program that replaces all the tags <a href=…>…</a> with corresponding tags [URL href=…]…[/URL].
    Read lines until you get the "END" command.
    Note: a tag can start and end on different lines, but actual keywords like "href=" or the closing tag "</a>" will never be split.
    For example, you will never get:
        <a hr
        ef="http://softuni.bg">SoftUni</
        a>

    Hints
    • Use a string builder to read the whole input into a single string. Make sure to save the new lines.
    • Create a pattern that can match a valid tag on multiple lines. Note that href= and </a> will never be split.
    • Use a string builder to replace all matches.

    Examples:
        <ul> <li> <a                                                                <ul> <li> [URL href="http://softuni.bg"]SoftUni[/URL]
        href="http://softuni.bg">SoftUni</a>                 ->                      </li> </ul>
         </li> </ul>
        END

        <a href="/">                                                                [URL href="/"]
        Link</a>                                            ->                      Link[/URL]
        END
*/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ReplaceA_Tag {
    public static void main(String[] args) {
        StringBuilder htmlText = new StringBuilder();

        try (BufferedReader reader =
                     new BufferedReader(new InputStreamReader(System.in))) {

            String inputLine = reader.readLine();
            while (!inputLine.equals("END")) {
                htmlText.append(inputLine).append(System.lineSeparator());

                inputLine = reader.readLine();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

        String output = htmlText.toString()
                .replaceAll("<a\\s([^>]+)>([^<]+)</a>", "[URL $1]$2[/URL]");

        System.out.println(output);
    }
}