@Override
 protected String doInBackground(Void... params) {
   return NetworkUtil.postRequestAPI("user/clearmsg", null);
 }
 @Override
 protected String doInBackground(Void... params) {
   String url = "user/deletemsg?msg_id=" + m_msgId;
   return NetworkUtil.postRequestAPI(url, m_params);
 }
 @Override
 protected String doInBackground(Void... params) {
   return NetworkUtil.postRequestAPI(
       String.format("meeting/join?meeting_code=%s", m_meetingCode), m_params);
 }