code: public void setServerName(String serverName) {
      if (serverName == null || serverName.equals("")) {
        this.serverName = "localhost";
      } else {
        this.serverName = serverName;
      }
    }
docs: Sets the name of the host the PostgreSQL database is running on. If this is changed, it will
  only affect future calls to getConnection. The default value is <tt>localhost</tt>.
  
  @param serverName name of the host the PostgreSQL database is running on