Calculating days between two dates with Java

Question

I want a Java program that calculates days between two dates    Type the first date  German notation  with whitespaces   dd mm yyyy   Type the second date  The program should calculates the number of days between the two dates    How can I include leap years and summertime   My code   import java util Calendar  import java util Date  import java util Scanner   public class NewDateDifference        public static void main String   args             System out print  Insert first date              Scanner s   new Scanner System in           String   eingabe1   new String 3            while  s hasNext                  int i   0              insert1 i    s next                if   s hasNext                      s close                    break                            i                       System out print  Insert second date              Scanner t   new Scanner System in           String   insert2   new String 3            while  t hasNext                  int i   0              insert2 i    t next                if   t hasNext                      t close                    break                            i                       Calendar cal   Calendar getInstance             cal set Calendar DAY OF MONTH  Integer parseInt insert1 0             cal set Calendar MONTH  Integer parseInt insert1 1             cal set Calendar YEAR  Integer parseInt insert1 2             Date firstDate   cal getTime             cal set Calendar DAY OF MONTH  Integer parseInt insert2 0             cal set Calendar MONTH  Integer parseInt insert2 1             cal set Calendar YEAR  Integer parseInt insert2 2             Date secondDate   cal getTime              long diff   secondDate getTime   - firstDate getTime             System out println   Days      diff   1000   60   60   24

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When I run your program  it doesn t even get me  to the point where I can enter the second date   This is simpler and less error prone   import java io BufferedReader  import java io InputStreamReader  import java text SimpleDateFormat  import java util Date   public class Test001        public static void main String   args  throws Exception            BufferedReader br   null           br   new BufferedReader new InputStreamReader System in            SimpleDateFormat sdf   new SimpleDateFormat  dd MM yyyy             System out println  Insert first date               Date dt1   sdf parse br readLine   trim              System out println  Insert second date               Date dt2   sdf parse br readLine   trim              long diff   dt2 getTime   - dt1 getTime             System out println  Days      diff   1000L   60L   60L   24L            if  br    null                br close

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Simplest way    public static long getDifferenceDays Date d1  Date d2        long diff   d2 getTime   - d1 getTime        return TimeUnit DAYS convert diff  TimeUnit MILLISECONDS

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The best way  and it converts to a String as bonus     protected void onCreate Bundle savedInstanceState         super onCreate savedInstanceState       setContentView R layout activity main       try             Dates to compare         String CurrentDate    09 24 2015           String FinalDate    09 26 2015            Date date1          Date date2           SimpleDateFormat dates   new SimpleDateFormat  MM dd yyyy               Setting dates         date1   dates parse CurrentDate           date2   dates parse FinalDate              Comparing dates         long difference   Math abs date1 getTime   - date2 getTime             long differenceDates   difference    24   60   60   1000              Convert long to String         String dayDifference   Long toString differenceDates            Log e  HERE   HERE      dayDifference             catch  Exception exception            Log e  DIDN T WORK    exception     exception

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Java date libraries are notoriously broken  I would advise to use Joda Time  It will take care of leap year  time zone and so on for you   Minimal working example   import java util Scanner  import org joda time DateTime  import org joda time Days  import org joda time LocalDate  import org joda time format DateTimeFormat  import org joda time format DateTimeFormatter   public class DateTestCase        public static void main String   args             System out print  Insert first date              Scanner s   new Scanner System in           String firstdate   s nextLine            System out print  Insert second date              String seconddate   s nextLine                Formatter         DateTimeFormatter dateStringFormat   DateTimeFormat                  forPattern  dd MM yyyy            DateTime firstTime   dateStringFormat parseDateTime firstdate           DateTime secondTime   dateStringFormat parseDateTime seconddate           int days   Days daysBetween new LocalDate firstTime                                       new LocalDate secondTime   getDays            System out println  Days between the two dates     days

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In Java 8  you could accomplish this by using LocalDate and DateTimeFormatter  From the Javadoc of LocalDate      LocalDate is an immutable date-time object that represents a date    often viewed as year-month-day    And the pattern can be constructed using DateTimeFormatter  Here is the Javadoc  and the relevant pattern characters I used      Symbol - Meaning - Presentation - Examples      y - year-of-era - year - 2004  04      M L - month-of-year - number text - 7  07  Jul    July  J      d - day-of-month - number - 10   Here is the example   import java io BufferedReader  import java io IOException  import java io InputStreamReader  import java time LocalDate  import java time format DateTimeFormatter  import java time temporal ChronoUnit   public class Java8DateExample       public static void main String   args  throws IOException           final DateTimeFormatter formatter   DateTimeFormatter ofPattern  dd MM yyyy            final BufferedReader reader   new BufferedReader new InputStreamReader System in            final String firstInput   reader readLine            final String secondInput   reader readLine            final LocalDate firstDate   LocalDate parse firstInput  formatter           final LocalDate secondDate   LocalDate parse secondInput  formatter           final long days   ChronoUnit DAYS between firstDate  secondDate           System out println  Days between      days             Example input output with more recent last   23 01 1997 27 04 1997 Days between  94   With more recent first   27 04 1997 23 01 1997 Days between  -94   Well  you could do it as a method in a simpler way   public static long betweenDates Date firstDate  Date secondDate  throws IOException       return ChronoUnit DAYS between firstDate toInstant    secondDate toInstant

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date format  it will be like  2015-01-01  private static final String DATE FORMAT    yyyy-MM-dd       convert a string to java util Date public static Date convertStringToJavaDate String date          throws ParseException       DateFormat dataFormat   new SimpleDateFormat DATE FORMAT       return dataFormat parse date         plus days to a date public static Date plusJavaDays Date date  int days           convert to jata-time     DateTime fromDate   new DateTime date       DateTime toDate   fromDate plusDays days          convert back to java util Date     return toDate toDate          return a list of dates between the fromDate and toDate public static List lt Date gt  getDatesBetween Date fromDate  Date toDate        List lt Date gt  dates   new ArrayList lt Date gt  0       Date date   fromDate      while  date before toDate     date equals toDate             dates add date           date   plusJavaDays date  1             return dates

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String dateStart    01 14 2015 08 29 58   String dateStop    01 15 2015 11 31 48      HH converts hour in 24 hours format  0-23   day calculation SimpleDateFormat format   new SimpleDateFormat  MM dd yyyy HH mm ss     Date d1   null  Date d2   null   d1   format parse dateStart   d2   format parse dateStop      in milliseconds long diff   d2 getTime   - d1 getTime     long diffSeconds   diff   1000   60  long diffMinutes   diff    60   1000    60  long diffHours   diff    60   60   1000    24  long diffDays   diff    24   60   60   1000    System out print diffDays     days      System out print diffHours     hours      System out print diffMinutes     minutes      System out print diffSeconds     seconds

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Most   all answers caused issues for us when daylight savings time came around   Here s our working solution for all dates  without using JodaTime  It utilizes calendar objects   public static int daysBetween Calendar day1  Calendar day2       Calendar dayOne    Calendar  day1 clone                dayTwo    Calendar  day2 clone         if  dayOne get Calendar YEAR     dayTwo get Calendar YEAR             return Math abs dayOne get Calendar DAY OF YEAR  - dayTwo get Calendar DAY OF YEAR          else           if  dayTwo get Calendar YEAR   gt  dayOne get Calendar YEAR                   swap them             Calendar temp   dayOne              dayOne   dayTwo              dayTwo   temp                    int extraDays   0           int dayOneOriginalYearDays   dayOne get Calendar DAY OF YEAR            while  dayOne get Calendar YEAR   gt  dayTwo get Calendar YEAR                 dayOne add Calendar YEAR  -1                  getActualMaximum   important for leap years             extraDays    dayOne getActualMaximum Calendar DAY OF YEAR                      return extraDays - dayTwo get Calendar DAY OF YEAR    dayOneOriginalYearDays

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Use   public int getDifferenceDays Date d1  Date d2        int daysdiff   0      long diff   d2 getTime   - d1 getTime        long diffDays   diff    24   60   60   1000    1      daysdiff    int  diffDays      return daysdiff

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UPDATE  The original answer from 2013 is now outdated because some of the classes have been replaced  The new way of doing this is using the new java time classes   DateTimeFormatter dtf   DateTimeFormatter ofPattern  dd MM yyyy    String inputString1    23 01 1997   String inputString2    27 04 1997    try       LocalDateTime date1   LocalDate parse inputString1  dtf       LocalDateTime date2   LocalDate parse inputString2  dtf       long daysBetween   Duration between date1  date2  toDays        System out println   Days      daysBetween     catch  ParseException e        e printStackTrace        Note that this solution will give the number of actual 24 hour-days  not the number of calendar days  For the latter  use   long daysBetween   ChronoUnit DAYS between date1  date2      Original answer  outdated as of Java 8   You are making some conversions with your Strings that are not necessary  There is a SimpleDateFormat class for it - try this   SimpleDateFormat myFormat   new SimpleDateFormat  dd MM yyyy    String inputString1    23 01 1997   String inputString2    27 04 1997    try       Date date1   myFormat parse inputString1       Date date2   myFormat parse inputString2       long diff   date2 getTime   - date1 getTime        System out println   Days      TimeUnit DAYS convert diff  TimeUnit MILLISECONDS      catch  ParseException e        e printStackTrace        EDIT  Since there have been some discussions regarding the correctness of this code  it does indeed take care of leap years  However  the TimeUnit DAYS convert function loses precision since milliseconds are converted to days  see the linked doc for more info   If this is a problem  diff can also be converted by hand   float days    diff    1000 60 60 24      Note that this is a float value  not necessarily an int

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We can make use of LocalDate and ChronoUnit java library  Below code is working fine    Date should be in format yyyy-MM-dd    import java time LocalDate  import java time temporal ChronoUnit  import java util    class Solution       public int daysBetweenDates String date1  String date2            LocalDate dt1   LocalDate parse date1           LocalDate dt2  LocalDate parse date2            long diffDays   ChronoUnit DAYS between dt1  dt2            return Math abs  int diffDays

[java] Calculating days between two dates with Java

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