code: public static String maxLengthString(String... strings) {
          String res = "";
          for (String string : strings) {
              if (string.length() > res.length()) {
                  res = string;
              }
          }
          return res;
      }
docs: 返回多个字符串中长度最长的字符串
  
  @param strings 多个字符串
  
  @return {@link String}