EmailValidator.java

import java.util.regex.Pattern;

public final class EmailValidator {

    private static final int MAX_EMAIL_LENGTH = 254;

    // Simple email format validation 
    private static final String EMAIL_REGEX =
        "^[a-zA-Z0-9_+%*-]+(?:\\.[a-zA-Z0-9_+%*-]+)*"
                + "@(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,}$";


    private static final Pattern EMAIL_PATTERN =
            Pattern.compile(EMAIL_REGEX);

    private EmailValidator() {
        // Utility class: instantiation is not required
    }

    public static String validate(String email) {

        if (email == null || email.isBlank()) {
            throw new InvalidEmailException(
                    "Email address cannot be null or blank."
            );
        }

        String trimmedEmail = email.trim();

        if (trimmedEmail.length() > MAX_EMAIL_LENGTH) {
            throw new InvalidEmailException(
                    "Email address exceeds the maximum length of "
                            + MAX_EMAIL_LENGTH + " characters."
            );
        }

        if (!EMAIL_PATTERN.matcher(trimmedEmail).matches()) {
            throw new InvalidEmailException(
                    "Invalid email address format: " + trimmedEmail
            );
        }

        return trimmedEmail;
    }

    public static boolean isValid(String email) {
        try {
            validate(email);
            return true;
        } catch (InvalidEmailException exception) {
            return false;
        }
    }

    public static class InvalidEmailException extends RuntimeException {

        public InvalidEmailException(String message) {
            super(message);
        }
    }
}