Porównaj dwa razy w Javie
String startTime = "10:00";
String endTime = "12:00";
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
Date d1 = sdf.parse(startTime);
Date d2 = sdf.parse(endTime);
long elapsed = d2.getTime() - d1.getTime();
System.out.println(elapsed);
Tough Tarsier