How to subtract dates in Java?

Or maybe a monster)):

public static void main(String[] args) throws ParseException {

    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm");

    Date dateS = format.parse("2016-05-11 00:46");
    Date dateE = format.parse("2016-05-12 12:26");

    long delt = dateE.getTime() - dateS.getTime();

    String result = String.format("%dд %dч %dмин",  
                                   delt / 86400000,  
                                   (delt % 86400000) / 3600000,  
                                   (delt % 3600000) / 60000);

    System.out.println(result);
}  

Answer: 1d 11h 40min
86400000-respectively days.
Next, we operate with the remainder of the division))

You can use the java.time.* package that appeared in Java 8:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");

LocalDateTime start = LocalDateTime.parse("2016-05-11 00:46", formatter);
LocalDateTime end = LocalDateTime.parse("2018-05-12 12:26", formatter);

Duration duration = Duration.between(start, end);

System.out.printf(
    "%dд %dч %dмин%n",
    duration.toDays(),
    duration.toHours() % 24,
    duration.toMinutes() % 60
);

You need to convert your dates to the Date type and assign them to two variables, startDate and endDate

Date startDate = ...
Date endDate   = ...

long duration  = endDate.getTime() - startDate.getTime();

long diffInSeconds = TimeUnit.MILLISECONDS.toSeconds(duration);
long diffInMinutes = TimeUnit.MILLISECONDS.toMinutes(duration);
long diffInHours = TimeUnit.MILLISECONDS.toHours(duration);