DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Calendar calobj = Calendar.getInstance();
System.out.println(df.format(calobj.getTime()));

new SimpleDateFormat("yyyy-MM-dd'T'HH:mm'Z'");

ZonedDateTime dateTime = ZonedDateTime.now();
System.out.println(DateTimeFormatter.ISO_INSTANT.format(dateTime));

DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssX");
df.setTimeZone(TimeZone.getTimeZone("UTC"));
Calendar calobj = Calendar.getInstance();
System.out.println(df.format(calobj.getTime()));