How To Set Time For Calendar

I would like to set a specific time for a Calendar instance. My below code will set a time one minute ahead of the current time, and format it to ISO8601 standard.

Java Code:

Calendar reminderDate = Calendar.getInstance();
System.out.println(dateFormat.format(reminderDate.getTime()));
reminderDate.add(Calendar.MINUTE,1);
SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
String finalReminderDate = sdf1.format(reminderDate.getTime()); mh_sh_highlight_all('java');

I now want to set another variable(deadlineDate), but to a specific time, say 5 minutes ahead. I would like to hardcode this in so I dont want it to change as a result of getting the instance of the Calendar(which sets it to the current time)

Essentially I am trying to regenerate the above code every minute and increment itself each cycle until it reaches the deadlineDate, which is a fixed datetime.

How can I do this?