Calculate days, months, and years elapsed between start and end date

Question

i am working on date calculation application like windows 10 calculator where you select start and end date and calculate days month and year

  public String differenceInDates(){
                Date start_date = convertStringToDate("2017-04-24");
                Date end_date = convertStringToDate("2018-07-24");
                long different = this.end_date.getTime() - this.start_date.getTime();

                        long millisInSeconds = 1000;
                        long millisInMinutes = millisInSeconds * 60;
                        long millisInHours = millisInMinutes * 60;
                        long millisInDay = millisInHours *24;

                        long elapsedDays = different / millisInDay;
                        different = different % millisInDay;

                        long elapsedHours = different / millisInHours;
                        different = different % millisInHours;

                        long elapsedMinutes = different / millisInMinutes;
                        different = different % millisInMinutes;

                        long elapsedSeconds = different / millisInSeconds;
                        if (elapsedHours == 0){
                            return String.valueOf("days"+elapsedDays+":"+":"+elapsedMinutes+":"+elapsedSeconds);
                        }
                        if (elapsedMinutes == 0){
                            return String.valueOf("days"+elapsedDays+":"+":"+elapsedHours+":"+elapsedSeconds);
                        }
                        if (elapsedHours == 0 && elapsedMinutes == 0){
                            return String.valueOf("days"+elapsedDays);
                        }
                        return String.valueOf("days"+elapsedDays+":"+" Hours"+elapsedHours+":"+" Minutes"+elapsedMinutes+":"+elapsedSeconds);
                }

                private Date convertStringToDate(String strDate) throws ParseException {
                        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
                        Date date = simpleDateFormat.parse(strDate);
                        return date;
                    }

i want answer like this

1 year 3 months

@fantaghirocco Not quite a duplicate of that. This question is about year-month-days scale, while that question is about hours-minutes-seconds scale. Different problems with different solutions. — Basil Bourque, Aug 30 '18 at 19:25
FYI, the terribly troublesome old date-time classes such as [`java.util.Date`](https://docs.oracle.com/javase/10/docs/api/java/util/Date.html), [`java.util.Calendar`](https://docs.oracle.com/javase/10/docs/api/java/util/Calendar.html), and `java.text.SimpleDateFormat` are now [legacy](https://en.wikipedia.org/wiki/Legacy_system), supplanted by the [*java.time*](https://docs.oracle.com/javase/10/docs/api/java/time/package-summary.html) classes built into Java 8 and later. See [*Tutorial* by Oracle](https://docs.oracle.com/javase/tutorial/datetime/TOC.html). — Basil Bourque, Aug 30 '18 at 19:28
Also similar to: [*Java 8: Calculate difference between two LocalDateTime](https://stackoverflow.com/q/25747499/642706) — Basil Bourque, Aug 30 '18 at 20:15

score 2 · Answer 1 · edited Aug 30 '18 at 19:26

2

java.time

If you can use LocalDate & Period, then it's quite simple:

LocalDate date1 = LocalDateTime.of(2018, Month.SEPTEMBER, 2, 13, 40);
LocalDate date2 = LocalDateTime.of(2018, Month.SEPTEMBER, 2, 13, 40);
Period period = Period.between(date1, date2);
System.out.println(period.getYears() + " year " + period.getMonths() + " months");

edited Aug 30 '18 at 19:26

Basil Bourque

303,325
100
852
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answered Aug 30 '18 at 15:58

achAmháin

4,176
4
17
40

score 0 · Answer 2 · answered Aug 30 '18 at 13:54

you can use this code:

SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");
            String CURRDATE = "16-07-1991";
            String EFFDATE = "28-08-2018";

            Date startdate = null;
            Date enddate = null;
            try {
                startdate = formatter.parse(CURRDATE);
                enddate = formatter.parse(EFFDATE);
            } catch (ParseException e) {
                e.printStackTrace();
            }

            Calendar startCalendar = new GregorianCalendar();
            startCalendar.setTime(startdate);

            Calendar endCalendar = new GregorianCalendar();
            endCalendar.setTime(enddate);

            int monthCount = 0;
            int firstDayInFirstMonth = startCalendar.get(Calendar.DAY_OF_MONTH);
            startCalendar.set(Calendar.DAY_OF_MONTH, 1);
            endCalendar.add(Calendar.DAY_OF_YEAR, -firstDayInFirstMonth + 1);

            while (!startCalendar.after(endCalendar)) {
                startCalendar.add(Calendar.MONTH, 1);
                ++monthCount;
            }

            startCalendar.add(Calendar.MONTH, -1);
            --monthCount;
            int remainingDays = 0;
            while (!startCalendar.after(endCalendar)) {
                startCalendar.add(Calendar.DAY_OF_YEAR, 1);
                ++remainingDays;
            }

            startCalendar.add(Calendar.DAY_OF_YEAR, -1);
            --remainingDays;

            int lastMonthMaxDays = endCalendar.getActualMaximum(Calendar.DAY_OF_MONTH);
            if (remainingDays >= lastMonthMaxDays) {
                ++monthCount;
                remainingDays -= lastMonthMaxDays;
            }

            int diffMonth = monthCount % 12;
            int diffYear = monthCount / 12;
            int diffDay = remainingDays;

            System.out.println(diffYear + " Year(s) and " + diffMonth + " Month(s) and " + diffDay + " Day(s)");

The result is:

27 Year(s) and 1 Month(s) and 12 Day(s)

Calculate days, months, and years elapsed between start and end date

2 Answers2

java.time