Java Regex: Valid Usernames

/*
 * You are part of the back-end development team of the next Facebook.
 * You are given a line of usernames, between one of the following symbols: space, “/”, “\”, “(“, “)”.
 * First you have to export all valid usernames. A valid username starts with a letter and can contain only letters, digits and “_”.
 * It cannot be less than 3 or more than 25 symbols long.
 * Your task is to sum the length of every 2 consecutive valid usernames and print on the console
 *   the 2 valid usernames with biggest sum of their lengths, each on a separate line.
 *
 * The Input comes from the console. One line will hold all the data. The line will hold characters in the range [0 … 9999].
 * It will hold usernames, divided by the symbols: space, “/”, “\”, “(“, “)”.
 * The input data will always be valid and in the format described. There is no need to check it explicitly.
 *
 * Print at the console the 2 consecutive valid usernames with the biggest sum of their lengths each on a separate line.
 * If there are 2 or more couples of usernames with the same sum of their lengths, print he left most.
 */


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class ValidUsernames {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] usernames = reader.readLine().split("[\\s()/\\\\]+");

        ArrayList<String> validNames = new ArrayList<>(usernames.length);

        Pattern pattern = Pattern.compile("\\b[a-zA-Z]\\w{2,24}\\b");
        Matcher matcher;
        for (String username : usernames) {
            matcher = pattern.matcher(username);
            if (matcher.find()) {
                validNames.add(username);
            }
        }

        int maxSum = 0;
        int indexSecondName = 1;
        for (int i = 1; i < validNames.size(); i++) {
            int currentSum = validNames.get(i).length() + validNames.get(i - 1).length();
            if (currentSum > maxSum) {
                maxSum = currentSum;
                indexSecondName = i;
            }
        }

        System.out.println(validNames.get(indexSecondName - 1));
        System.out.println(validNames.get(indexSecondName));
    }
}