code: public static String format(String msg, Object... args) {
  
          if (args == null || args.length == 0)
              return msg;
  
          StringBuilder sb = new StringBuilder();
          int argId = 0;
          for (int i = 0; i < msg.length(); i++) {
  
              final char c = msg.charAt(i);
              if (c == '{' && msg.charAt(i + 1) == '}') {
                  if (args.length > argId) {
                      Object val = args[argId++];
                      if (val == null)
                          sb.append("null");
                      else
                          sb.append(val.toString());
                  } else {
                      sb.append("{{MISSING ARG}}");
                  }
                  i++;
              } else {
                  sb.append(c);
              }
          }
          return sb.toString();
      }
docs: Similar to Slf4J logger