[java] java 휴대폰번호 마스킹 가운데 4자리 마스킹

public static String phoneMasking(String phoneNo) throws Exception {
    String regex = "(\\d{2,3})-?(\\d{3,4})-?(\\d{4})$";

    Matcher matcher = Pattern.compile(regex).matcher(phoneNo);
    if(matcher.find()) {
        String target = matcher.group(2);
        int length = target.length();
        char[] c = new char[length];
        Arrays.fill(c, '*');

        return phoneNo.replace(target, String.valueOf(c));
    }
    return phoneNo;
}