Java Utililty Methods QQ Number Check

if (qq == null || qq.trim().length() == 0) {
    return false;
return Regex_QQ.matcher(qq).matches();

Pattern pattern = Pattern.compile("^[1-9][0-9]{4,14}$");
return pattern.matcher(qq).matches();

return !Strings.isNullOrEmpty(str) && str.matches(QQ);

boolean result = validByRegex("^[1-9]\\d{4,9}$", str);
return result;