How can I find the number of years between two dates

Question

I am trying to determine an age in years from a certain date   Does anyone know a clean way to do this in Android   I have the Java api available obviously  but the straight-up java api is pretty weak  and I was hoping that Android has something to help me out   EDIT  The multiple recommendations to use Joda time in Android worries me a bit due to Android Java - Joda Date is slow and related concerns   Also  pulling in a library not shipped with the platform for something this size is probably overkill

User · Answer

I would recommend using the great Joda-Time library for everything date related in Java   For your needs you can use the Years yearsBetween   method

User · Answer

Here s what I think is a better method   public int getYearsBetweenDates Date first  Date second        Calendar firstCal   GregorianCalendar getInstance        Calendar secondCal   GregorianCalendar getInstance         firstCal setTime first       secondCal setTime second        secondCal add Calendar DAY OF YEAR  1 - firstCal get Calendar DAY OF YEAR         return secondCal get Calendar YEAR  - firstCal get Calendar YEAR       EDIT  Apart from a bug which I fixed  this method does not work well with leap years  Here s a complete test suite  I guess you re better off using the accepted answer   import java text SimpleDateFormat  import java util Calendar  import java util Date  import java util GregorianCalendar   class YearsBetweenDates       public static int getYearsBetweenDates Date first  Date second            Calendar firstCal   GregorianCalendar getInstance            Calendar secondCal   GregorianCalendar getInstance             firstCal setTime first           secondCal setTime second            secondCal add Calendar DAY OF YEAR  1 - firstCal get Calendar DAY OF YEAR             return secondCal get Calendar YEAR  - firstCal get Calendar YEAR              private static class TestCase           public Calendar date1          public Calendar date2          public int expectedYearDiff          public String comment           public TestCase Calendar date1  Calendar date2  int expectedYearDiff  String comment                this date1   date1              this date2   date2              this expectedYearDiff   expectedYearDiff              this comment   comment                       private static TestCase   tests             new TestCase                  new GregorianCalendar 2014  Calendar JULY  15                   new GregorianCalendar 2015  Calendar JULY  15                   1                   exactly one year            new TestCase                  new GregorianCalendar 2014  Calendar JULY  15                   new GregorianCalendar 2017  Calendar JULY  14                   2                   one day less than 3 years            new TestCase                  new GregorianCalendar 2015  Calendar NOVEMBER  3                   new GregorianCalendar 2017  Calendar MAY  3                   1                   a year and a half            new TestCase                  new GregorianCalendar 2016  Calendar JULY  15                   new GregorianCalendar 2017  Calendar JULY  15                   1                   leap years do not compare correctly                public static void main String   args            SimpleDateFormat df   new SimpleDateFormat  yyyy-MM-dd            for  TestCase t   tests                int diff   getYearsBetweenDates t date1 getTime    t date2 getTime                 String result   diff    t expectedYearDiff    PASS     FAIL               System out println t comment                              df format t date1 getTime        - gt                          df format t date2 getTime                                  diff          result

User · Answer

I know you have asked for a clean solution  but here are two dirty once           static void diffYears1         SimpleDateFormat dateFormat   new SimpleDateFormat  dd-MM-yyyy        Calendar calendar1   Calendar getInstance       now     String toDate   dateFormat format calendar1 getTime          Calendar calendar2   Calendar getInstance        calendar2 add Calendar DAY OF YEAR  -7000      some date in the past     String fromDate   dateFormat format calendar2 getTime             just simply add one year at a time to the earlier date until it becomes later then the other one      int years   0      while true                calendar2 add Calendar YEAR  1           if calendar2 getTimeInMillis    lt  calendar1 getTimeInMillis                years            else             break             System out println years     years between     fromDate     and     toDate      static void diffYears2         SimpleDateFormat dateFormat   new SimpleDateFormat  dd-MM-yyyy        Calendar calendar1   Calendar getInstance       now     String toDate   dateFormat format calendar1 getTime          Calendar calendar2   Calendar getInstance        calendar2 add Calendar DAY OF YEAR  -7000      some date in the past     String fromDate   dateFormat format calendar2 getTime             first get the years difference from the dates themselves     int years   calendar1 get Calendar YEAR  - calendar2 get Calendar YEAR          now make the earlier date the same year as the later     calendar2 set Calendar YEAR  calendar1 get Calendar YEAR           and see if new date become later  if so then one year was not whole  so subtract 1      if calendar2 getTimeInMillis    gt  calendar1 getTimeInMillis            years--       System out println years     years between     fromDate     and     toDate

User · Answer

Thanks  Ole V v for reviewing it  i have found some inbuilt library classes which does the same       int noOfMonths   0      org joda time format DateTimeFormatter formatter   DateTimeFormat              forPattern  yyyy-MM-dd        DateTime dt   formatter parseDateTime startDate        DateTime endDate11   new DateTime        Months m   Months monthsBetween dt  endDate11       noOfMonths   m getMonths        System out println noOfMonths

User · Answer

If you don t want to calculate it using java s Calendar you can use Androids Time class  It is supposed to be faster but I didn t notice much difference when i switched   I could not find any pre-defined functions to determine time between 2 dates for an age in Android   There are some nice helper functions to get formatted time between dates in the DateUtils but that s probably not what you want

User · Answer

import java util Calendar  import java util Locale  import static java util Calendar    import java util Date   public static int getDiffYears Date first  Date last        Calendar a   getCalendar first       Calendar b   getCalendar last       int diff   b get YEAR  - a get YEAR       if  a get MONTH   gt  b get MONTH               a get MONTH     b get MONTH   amp  amp  a get DATE   gt  b get DATE              diff--            return diff     public static Calendar getCalendar Date date        Calendar cal   Calendar getInstance Locale US       cal setTime date       return cal

User · Answer

I apparently can t comment yet  but I think you can just use the DAY OF YEAR to workout if you should adjust the years down one  copied and modified from current best answer   public static int getDiffYears Date first  Date last        Calendar a   getCalendar first       Calendar b   getCalendar last       int diff   b get Calendar YEAR  - a get Calendar YEAR       if  a get Calendar DAY OF YEAR   gt  b get Calendar DAY OF YEAR             diff--            return diff     public static Calendar getCalendar Date date        Calendar cal   Calendar getInstance Locale US       cal setTime date       return cal      Similarly you could probably just diff the ms representations of the time and divide by the number of ms in a year   Just keep everything in longs and that should be good enough most of the time  leap years  ouch  but it depends on your application for the number of years and how performant that function has to be weather it would be worth that kind of hack

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int year  2000   int month  9      int day 30       public int getAge  int year  int month  int day                 GregorianCalendar cal   new GregorianCalendar                int y  m  d  noofyears                        y   cal get Calendar YEAR     current year               m   cal get Calendar MONTH     current month              d   cal get Calendar DAY OF MONTH    current day             cal set year  month  day     here ur date              noofyears   y - cal get Calendar YEAR               if   m  lt  cal get Calendar MONTH                                    m    cal get Calendar MONTH    amp  amp   d  lt  cal                                              get Calendar DAY OF MONTH                           --noofyears                            if noofyears  lt  0                      throw new IllegalArgumentException  age  lt  0                 System out println noofyears               return noofyears

User · Answer

tl dr  ChronoUnit YEARS between       LocalDate of  2010   1   1          LocalDate now  ZoneId of   America Montreal           java time  The old date-time classes really are bad  so bad that both Sun  amp  Oracle agreed to supplant them with the java time classes  If you do any significant work at all with date-time values  adding a library to your project is worthwhile  The Joda-Time library was highly successful and recommended  but is now in maintenance mode  The team advises migration to the java time classes    Much of the java time functionality is back-ported to Java 6  amp  7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP  see How to use       LocalDate start   LocalDate of  2010   1   1     LocalDate stop   LocalDate now  ZoneId of   America Montreal       long years   java time temporal ChronoUnit YEARS between  start   stop      Dump to console   System out println   start      start       stop      stop       years      years          start  2010-01-01   stop  2016-09-06   years  6         About java time  The java time framework is built into Java 8 and later  These classes supplant the troublesome old legacy date-time classes such as java util Date  Calendar   amp  SimpleDateFormat   The Joda-Time project  now in maintenance mode  advises migration to the java time classes   To learn more  see the Oracle Tutorial  And search Stack Overflow for many examples and explanations  Specification is JSR 310   You may exchange java time objects directly with your database  Use a JDBC driver compliant with JDBC 4 2 or later  No need for strings  no need for java sql   classes   Where to obtain the java time classes     Java SE 8  Java SE 9  Java SE 10  Java SE 11  and later  - Part of the standard Java API with a bundled implementation    Java 9 adds some minor features and fixes   Java SE 6 and Java SE 7   Most of the java time functionality is back-ported to Java 6  amp  7 in ThreeTen-Backport   Android   Later versions of Android bundle implementations of the java time classes  For earlier Android   lt 26   the ThreeTenABP project adapts ThreeTen-Backport  mentioned above   See How to use ThreeTenABP

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This will work and if you want the number of years replace 12 to 1       String date1    07-01-2015       String date2    07-11-2015       int i   Integer parseInt date1 substring 6        int j   Integer parseInt date2 substring 6        int p   Integer parseInt date1 substring 3 5        int q   Integer parseInt date2 substring 3 5          int z      if q gt  p           z q-p    j-i  12       else          z p-q    j-i  12            System out println  The Total Months difference between two dates is -- gt    z   Months

User · Answer

Try this   int getYear Date date1 Date date2          SimpleDateFormat simpleDateformat new SimpleDateFormat  yyyy          Integer parseInt simpleDateformat format date1           return Integer parseInt simpleDateformat format date2  - Integer parseInt simpleDateformat format date1

[java] How can I find the number of years between two dates?

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