Java 8 Difference between two LocalDateTime in multiple units

Question

I am trying to calculate the difference between two LocalDateTime    The output needs to be of the format y years m months d days h hours m minutes s seconds  Here is what I have written   import java time Duration  import java time Instant  import java time LocalDateTime  import java time Period  import java time ZoneId   public class Main        static final int MINUTES PER HOUR   60      static final int SECONDS PER MINUTE   60      static final int SECONDS PER HOUR   SECONDS PER MINUTE   MINUTES PER HOUR       public static void main String   args            LocalDateTime toDateTime   LocalDateTime of 2014  9  9  19  46  45           LocalDateTime fromDateTime   LocalDateTime of 1984  12  16  7  45  55            Period period   getPeriod fromDateTime  toDateTime           long time     getTime fromDateTime  toDateTime            System out println period getYears       years                      period getMonths       months                      period getDays       days                     time 0      hours                     time 1      minutes                     time 2      seconds                  private static Period getPeriod LocalDateTime dob  LocalDateTime now            return Period between dob toLocalDate    now toLocalDate                private static long   getTime LocalDateTime dob  LocalDateTime now            LocalDateTime today   LocalDateTime of now getYear                    now getMonthValue    now getDayOfMonth    dob getHour    dob getMinute    dob getSecond             Duration duration   Duration between today  now            long seconds   duration getSeconds             long hours   seconds   SECONDS PER HOUR          long minutes     seconds   SECONDS PER HOUR    SECONDS PER MINUTE           long secs    seconds   SECONDS PER MINUTE            return new long   hours  minutes  secs             The output that I am getting is 29 years 8 months 24 days 12 hours 0 minutes 50 seconds  I have checked my result from this website  with values 12 16 1984 07 45 55 and 09 09 2014 19 46 45   The following screenshot shows the output     I am pretty sure that the fields after the month value is coming wrong from my code  Any suggestion would be very helpful   Update  I have tested my result from another website and the result I got is different  Here it is  Calculate duration between two dates  result  29 years  8 months  24 days  12 hours  0 minutes and 50 seconds    Update  Since I got two different results from two different sites  I am wondering if the algorithm of my calculation is legitimate or not  If I use following two LocalDateTime objects   LocalDateTime toDateTime   LocalDateTime of 2014  9  10  6  40  45   LocalDateTime fromDateTime   LocalDateTime of 1984  12  16  7  45  55     Then the output is coming  29 years 8 months 25 days -1 hours -5 minutes -10 seconds   From this link it should be 29 years 8 months 24 days 22 hours  54 minutes and 50 seconds  So the algorithm needs to handle the negative numbers too   Note the question is not about which site gave me what result  I need to know the right algorithm and need to have right results

User · Answer

After more than five years I answer my question. I think that the problem with a negative duration can be solved by a simple correction:

LocalDateTime fromDateTime = LocalDateTime.of(2014, 9, 9, 7, 46, 45);
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 46, 45);

Period period = Period.between(fromDateTime.toLocalDate(), toDateTime.toLocalDate());
Duration duration = Duration.between(fromDateTime.toLocalTime(), toDateTime.toLocalTime());

if (duration.isNegative()) {
    period = period.minusDays(1);
    duration = duration.plusDays(1);
}
long seconds = duration.getSeconds();
long hours = seconds / SECONDS_PER_HOUR;
long minutes = ((seconds % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
long secs = (seconds % SECONDS_PER_MINUTE);
long time[] = {hours, minutes, secs};
System.out.println(period.getYears() + " years "
            + period.getMonths() + " months "
            + period.getDays() + " days "
            + time[0] + " hours "
            + time[1] + " minutes "
            + time[2] + " seconds.");

Note: The site https://www.epochconverter.com/date-difference now correctly calculates the time difference.

Thank you all for your discussion and suggestions.

User · Answer

TL DR  Duration duration   Duration between start  end   duration   duration minusDays duration toDaysPart        essentially  duration  mod 1 day   Period period   Period between start toLocalDate    end toLocalDate       and then use the methods period getYears    period getMonths    period getDays    duration toHoursPart    duration toMinutesPart    duration toSecondsPart       Expanded answer  I ll answer the original question  i e  how to get the time difference between two LocalDateTimes in years  months  days  hours  amp  minutes  such that the  sum   see note below  of all the values for the different units equals the total temporal difference  and such that the value in each unit is smaller than the next bigger unit   i e  minutes  lt  60  hours  lt  24  and so on   Given two LocalDateTimes start and end  e g   LocalDateTime start   LocalDateTime of 2019  11  29  17  15   LocalDateTime end   LocalDateTime of 2020  11  30  18  44     we can represent the absolute timespan between the two with a Duration   perhaps using Duration between start  end   But the biggest unit we can extract out of a Duration is days  as a temporal unit equivalent to 24h    see the note below for an explanation  To use larger units  months  years  we can represent this Duration with a pair of  Period  Duration   where the Period measures the difference up to a precision of days and the Duration represents the remainder   Duration duration   Duration between start  end   duration   duration minusDays duration toDaysPart        essentially  duration  mod 1 day   Period period   Period between start toLocalDate    end toLocalDate       Now we can simply use the methods defined on Period and Duration to extract the individual units   System out printf   d years   d months   d days   d hours   d minutes   d seconds           period getYears    period getMonths    period getDays    duration toHoursPart            duration toMinutesPart    duration toSecondsPart       1 years  0 months  1 days  1 hours  29 minutes  0 seconds   or  using the default format   System out println period           duration     P1Y1D   PT1H29M     Note on years  months  amp  days  Note that  in java time s conception   units  like  month  or  year  don t represent a fixed  absolute temporal value   they re date- and calendar-dependent  as the following example illustrates   LocalDateTime         start1   LocalDateTime of 2020  1  1  0  0           end1   LocalDateTime of 2021  1  1  0  0           start2   LocalDateTime of 2021  1  1  0  0           end2   LocalDateTime of 2022  1  1  0  0   System out println Period between start1 toLocalDate    end1 toLocalDate      System out println Duration between start1  end1  toDays     System out println Period between start2 toLocalDate    end2 toLocalDate      System out println Duration between start2  end2  toDays       P1Y 366 P1Y 365

User · Answer

Here a single example using Duration and TimeUnit to get  hh mm ss  format   Duration dur   Duration between localDateTimeIni  localDateTimeEnd   long millis   dur toMillis     String format   02d  02d  02d            TimeUnit MILLISECONDS toHours millis           TimeUnit MILLISECONDS toMinutes millis  -          TimeUnit HOURS toMinutes TimeUnit MILLISECONDS toHours millis            TimeUnit MILLISECONDS toSeconds millis  -          TimeUnit MINUTES toSeconds TimeUnit MILLISECONDS toMinutes millis

User · Answer

And the version of  Thomas in Groovy with takes the desired units in a list instead of hardcoding the values  This implementation  which can easily ported to Java - I made the function declaration explicit  makes Thomas approach more reuseable   def fromDateTime   LocalDateTime of 1968  6  14  0  13  0  def toDateTime   LocalDateTime now   def listOfUnits         ChronoUnit YEARS  ChronoUnit MONTHS  ChronoUnit DAYS      ChronoUnit HOURS  ChronoUnit MINUTES  ChronoUnit SECONDS      ChronoUnit MILLIS   println calcDurationInTextualForm listOfUnits  fromDateTime  toDateTime       String calcDurationInTextualForm List lt ChronoUnit gt  listOfUnits  LocalDateTime ts  LocalDateTime to        def result           listOfUnits each   chronoUnit - gt          long amount   ts until to  chronoUnit          ts   ts plus amount  chronoUnit           if  amount                result  lt  lt    amount   chronoUnit toString                          result join           At the time of this writing the code above returns 47 Years  8 Months  9 Days  22 Hours  52 Minutes  7 Seconds  140 Millis  And  for  Gennady Kolomoets input  the code returns 23 Hours   When you provide a list of units it must be sorted by size of the units  biggest first    def listOfUnits    ChronoUnit WEEKS  ChronoUnit DAYS  ChronoUnit HOURS     returns 2495 Weeks  3 Days  8 Hours

User · Answer

It should be simpler  Duration between startLocalDateTime  endLocalDateTime  toMillis     You can convert millis to whatever unit you like  String format  quot  d minutes  d seconds quot      TimeUnit MILLISECONDS toMinutes millis     TimeUnit MILLISECONDS toSeconds millis  -    TimeUnit MINUTES toSeconds TimeUnit MILLISECONDS toMinutes millis

User · Answer

Unfortunately  there doesn t seem to be a period class that spans time as well  so you might have to do the calculations on your own   Fortunately  the date and time classes have a lot of utility methods that simplify that to some degree  Here s a way to calculate the difference although not necessarily the fastest   LocalDateTime fromDateTime   LocalDateTime of 1984  12  16  7  45  55   LocalDateTime toDateTime   LocalDateTime of 2014  9  10  6  40  45    LocalDateTime tempDateTime   LocalDateTime from  fromDateTime     long years   tempDateTime until  toDateTime  ChronoUnit YEARS    tempDateTime   tempDateTime plusYears  years     long months   tempDateTime until  toDateTime  ChronoUnit MONTHS    tempDateTime   tempDateTime plusMonths  months     long days   tempDateTime until  toDateTime  ChronoUnit DAYS    tempDateTime   tempDateTime plusDays  days      long hours   tempDateTime until  toDateTime  ChronoUnit HOURS    tempDateTime   tempDateTime plusHours  hours     long minutes   tempDateTime until  toDateTime  ChronoUnit MINUTES    tempDateTime   tempDateTime plusMinutes  minutes     long seconds   tempDateTime until  toDateTime  ChronoUnit SECONDS     System out println  years     years              months     months              days     days             hours     hours             minutes     minutes             seconds     seconds        prints  29 years 8 months 24 days 22 hours 54 minutes 50 seconds    The basic idea is this  create a temporary start date and get the full years to the end  Then adjust that date by the number of years so that the start date is less then a year from the end  Repeat that for each time unit in descending order   Finally a disclaimer  I didn t take different timezones into account  both dates should be in the same timezone  and I also didn t test check how daylight saving time or other changes in a calendar  like the timezone changes in Samoa  affect this calculation  So use with care

User · Answer

There is some problem for Tapas Bose code and Thomas code  If time differen e is negative  array gets the negative values  For example if   LocalDateTime toDateTime   LocalDateTime of 2014  9  10  6  46  45   LocalDateTime fromDateTime   LocalDateTime of 2014  9  9  7  46  45     it returns 0 years 0 months 1 days -1 hours 0 minutes 0 seconds   I think the right output is  0 years 0 months 0 days 23 hours 0 minutes 0 seconds   I propose to separate the LocalDateTime instances on LocalDate and LocalTime instances  After that we can obtain the Java 8 Period and Duration instances  The Duration instance is separated on the number of days and throughout-the-day time value   lt  24h  with subsequent correction of the period value  When the second LocalTime value is before the firstLocalTime value  it is necessary to reduce the period for one day   Here s my way to calculate the LocalDateTime difference   private void getChronoUnitForSecondAfterFirst LocalDateTime firstLocalDateTime  LocalDateTime secondLocalDateTime  long   chronoUnits          Separate LocaldateTime on LocalDate and LocalTime       LocalDate firstLocalDate   firstLocalDateTime toLocalDate        LocalTime firstLocalTime   firstLocalDateTime toLocalTime         LocalDate secondLocalDate   secondLocalDateTime toLocalDate        LocalTime secondLocalTime   secondLocalDateTime toLocalTime           Calculate the time difference       Duration duration   Duration between firstLocalDateTime  secondLocalDateTime       long durationDays   duration toDays        Duration throughoutTheDayDuration   duration minusDays durationDays       Logger getLogger PeriodDuration class getName    log Level INFO               Duration is      duration     this is     durationDays                 days and     throughoutTheDayDuration     time          Period period   Period between firstLocalDate  secondLocalDate          Correct the date difference       if  secondLocalTime isBefore firstLocalTime             period   period minusDays 1           Logger getLogger PeriodDuration class getName    log Level INFO                   minus 1 day               Logger getLogger PeriodDuration class getName    log Level INFO               Period between     firstLocalDateTime     and                 secondLocalDateTime     is      period     and duration is                  throughoutTheDayDuration                 n-----------------------------------------------------------------           Calculate chrono unit values and  write it in array       chronoUnits 0    period getYears        chronoUnits 1    period getMonths        chronoUnits 2    period getDays        chronoUnits 3    throughoutTheDayDuration toHours        chronoUnits 4    throughoutTheDayDuration toMinutes     60      chronoUnits 5    throughoutTheDayDuration getSeconds     60      The above method can be used to calculate the difference of any local date and time values  for example   public long   getChronoUnits String firstLocalDateTimeString  String secondLocalDateTimeString        DateTimeFormatter formatter   DateTimeFormatter ofPattern  yyyy-MM-dd HH mm ss         LocalDateTime firstLocalDateTime   LocalDateTime parse firstLocalDateTimeString  formatter       LocalDateTime secondLocalDateTime   LocalDateTime parse secondLocalDateTimeString  formatter        long   chronoUnits   new long 6       if  secondLocalDateTime isAfter firstLocalDateTime             getChronoUnitForSecondAfterFirst firstLocalDateTime  secondLocalDateTime  chronoUnits         else           getChronoUnitForSecondAfterFirst secondLocalDateTime  firstLocalDateTime  chronoUnits             return chronoUnits      It is convenient to write a unit test for the above method  both of them are PeriodDuration class members   Here s the code    RunWith Parameterized class  public class PeriodDurationTest    private final String firstLocalDateTimeString  private final String secondLocalDateTimeString  private final long   chronoUnits   public PeriodDurationTest String firstLocalDateTimeString  String secondLocalDateTimeString  long   chronoUnits        this firstLocalDateTimeString   firstLocalDateTimeString      this secondLocalDateTimeString   secondLocalDateTimeString      this chronoUnits   chronoUnits      Parameters public static Collection lt Object   gt  periodValues         long   chronoUnits0    0  0  0  0  0  0       long   chronoUnits1    0  0  0  1  0  0       long   chronoUnits2    0  0  0  23  0  0       long   chronoUnits3    0  0  0  1  0  0       long   chronoUnits4    0  0  0  23  0  0       long   chronoUnits5    0  0  1  23  0  0       long   chronoUnits6    29  8  24  12  0  50       long   chronoUnits7    29  8  24  12  0  50       return Arrays asList new Object                2015-09-09 21 46 44    2015-09-09 21 46 44   chronoUnits0             2015-09-09 21 46 44    2015-09-09 22 46 44   chronoUnits1             2015-09-09 21 46 44    2015-09-10 20 46 44   chronoUnits2             2015-09-09 21 46 44    2015-09-09 20 46 44   chronoUnits3             2015-09-10 20 46 44    2015-09-09 21 46 44   chronoUnits4             2015-09-11 20 46 44    2015-09-09 21 46 44   chronoUnits5             1984-12-16 07 45 55    2014-09-09 19 46 45   chronoUnits6             2014-09-09 19 46 45    1984-12-16 07 45 55   chronoUnits6              Test public void testGetChronoUnits         PeriodDuration instance   new PeriodDuration        long   expResult   this chronoUnits      long   result   instance getChronoUnits this firstLocalDateTimeString  this secondLocalDateTimeString       assertArrayEquals expResult  result          All tests are successful whether or not the value of the first LocalDateTime is before and for any LocalTime values

User · Answer

Here is a very simple answer to your question  It works   import java time    import java util    import java time format DateTimeFormatter  import java time temporal ChronoUnit   public class MyClass   public static void main String args          DateTimeFormatter T   DateTimeFormatter ofPattern  dd MM yyyy HH mm        Scanner h   new Scanner System in        System out print  Enter date of birth dd mm yyyy hh mm           String b   h nextLine         LocalDateTime bd   LocalDateTime parse b T       LocalDateTime cd   LocalDateTime now         long minutes   ChronoUnit MINUTES between bd  cd       long hours   ChronoUnit HOURS between bd  cd        System out print  Age is    hours    hours  or    minutes    minutes old

User · Answer

Joda-Time  Since many of the answers required API 26 support and my min API was 23  I solved it by below code     import org joda time Days  LocalDate startDate   Something LocalDate endDate   Something    The difference would be exclusive of both dates      so in most of use cases we may need to increment it by 1 Days daysBetween startDate  endDate  days

User · Answer

I found the best way to do this is with ChronoUnit   long minutes   ChronoUnit MINUTES between fromDate  toDate   long hours   ChronoUnit HOURS between fromDate  toDate     Additional documentation is here  https   docs oracle com javase tutorial datetime iso period html

[java] Java 8: Difference between two LocalDateTime in multiple units

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