How to iterate through range of Dates in Java

Question

In my script I need to perform a set of actions through range of dates  given a start and end date  Please provide me guidance to achieve this using Java   for   currentDate   starDate  currentDate  lt  endDate  currentDate           I know the above code is simply impossible  but I do it in order to show you what I d like to achieve

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This is essentially the same answer BalusC gave  but a bit more readable with a while loop in place of a for loop   Calendar start   Calendar getInstance    start setTime startDate    Calendar end   Calendar getInstance    end setTime endDate    while   start after end        Date targetDay   start getTime           Do Work Here      start add Calendar DATE  1

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JodaTime is nice  however  for the sake of completeness and or if you prefer API-provided facilities  here are the standard API approaches   When starting off with java util Date instances like below   SimpleDateFormat formatter   new SimpleDateFormat  yyyy-MM-dd    Date startDate   formatter parse  2010-12-20    Date endDate   formatter parse  2010-12-26      Here s the legacy java util Calendar approach in case you aren t on Java8 yet   Calendar start   Calendar getInstance    start setTime startDate   Calendar end   Calendar getInstance    end setTime endDate    for  Date date   start getTime    start before end   start add Calendar DATE  1   date   start getTime             Do your job here with  date       System out println date       And here s Java8 s java time LocalDate approach  basically exactly the JodaTime approach   LocalDate start   startDate toInstant   atZone ZoneId systemDefault    toLocalDate    LocalDate end   endDate toInstant   atZone ZoneId systemDefault    toLocalDate     for  LocalDate date   start  date isBefore end   date   date plusDays 1            Do your job here with  date       System out println date       If you d like to iterate inclusive the end date  then use  start after end  and  date isAfter end  respectively

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Why not use epoch and loop through easily    long startDateEpoch   new java text SimpleDateFormat  dd MM yyyy   parse startDate  getTime     1000       long endDateEpoch   new java text SimpleDateFormat  dd MM yyyy   parse endDate  getTime     1000        long i      for i startDateEpoch   i lt  endDateEpoch  i  86400            System out println i

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You can try this   OffsetDateTime currentDateTime   OffsetDateTime now    for  OffsetDateTime date   currentDateTime  date isAfter currentDateTime minusYears YEARS    date   date minusWeeks 1

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public static final void generateRange final Date dateFrom  final Date dateTo        final Calendar current   Calendar getInstance        current setTime dateFrom        while   current getTime   after dateTo                    TODO          current add Calendar DATE  1

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The following snippet  uses java time format of Java 8  maybe used to iterate over a date range       DateTimeFormatter formatter   DateTimeFormatter ofPattern  quot yyyy-MM-dd quot           Any chosen date format maybe taken       LocalDate startDate   LocalDate parse startDateString formatter       LocalDate endDate   LocalDate parse endDateString formatter       if endDate isBefore startDate                   error           LocalDate itr   null      for  itr   startDate  itr isBefore endDate   itr isEqual itr   itr   itr plusDays 1                   Processing  goes here        The plusMonths   plusYears   maybe chosen for time unit increment  Increment by a single day is being done in above illustration

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Java 8 style  using the java time classes      Monday  February 29 is a leap day in 2016  otherwise  February only has 28 days  LocalDate start   LocalDate parse  2016-02-28              end     LocalDate parse  2016-03-02        4 days between  end is inclusive in this example  Stream iterate start  date - gt  date plusDays 1            limit ChronoUnit DAYS between start  end    1           forEach System out  println     Output   2016-02-28 2016-02-29 2016-03-01 2016-03-02   Alternative   LocalDate next   start minusDays 1   while   next   next plusDays 1   isBefore end plusDays 1          System out println next       Java 9 added the datesUntil   method   start datesUntil end plusDays 1   forEach System out  println

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Here is Java 8 code  I think this code will solve your problem Happy Coding      LocalDate start   LocalDate now        LocalDate end   LocalDate of 2016  9  1    JAVA 9 release date     Long duration   start until end  ChronoUnit DAYS       System out println duration           Do Any stuff Here there after     IntStream iterate 0  i - gt  i   1                limit duration                forEach  i  - gt              old way of iteration     for  int i   0  i  lt  duration  i         System out print      i     Do Any stuff Here

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This will help you start 30 days back and loop through until today s date  you can easily change range of dates and direction   private void iterateThroughDates   throws Exception       Calendar start   Calendar getInstance        start add Calendar DATE  -30       Calendar end   Calendar getInstance        for  Calendar date   start  date before end   date add Calendar DATE  1                     System out println date getTime

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Apache Commons      for  Date dateIter   fromDate   dateIter after toDate   dateIter   DateUtils addDays dateIter  1

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We can migrate the logic to various methods foe Java 7  Java 8 and Java 9   public static List lt Date gt  getDatesRangeJava7 Date startDate  Date endDate        List lt Date gt  datesInRange   new ArrayList lt  gt         Calendar startCalendar   new GregorianCalendar        startCalendar setTime startDate       Calendar endCalendar   new GregorianCalendar        endCalendar setTime endDate       while  startCalendar before endCalendar             Date result   startCalendar getTime            datesInRange add result           startCalendar add Calendar DATE  1             return datesInRange     public static List lt LocalDate gt  getDatesRangeJava8 LocalDate startDate  LocalDate endDate        int numOfDays    int  ChronoUnit DAYS between startDate  endDate       return IntStream range 0  numOfDays               mapToObj startDate  plusDays               collect Collectors toList        public static List lt LocalDate gt  getDatesRangeJava9 LocalDate startDate  LocalDate endDate        return startDate datesUntil endDate  collect Collectors toList         Then we can invoke these methods as   SimpleDateFormat formatter   new SimpleDateFormat  yyyy-MM-dd    Date startDate   formatter parse  2010-12-20    Date endDate   formatter parse  2010-12-26    List lt Date gt  dateRangeList   getDatesRangeJava7 startDate  endDate   System out println dateRangeList    LocalDate startLocalDate   startDate toInstant   atZone ZoneId systemDefault    toLocalDate    LocalDate endLocalDate   endDate toInstant   atZone ZoneId systemDefault    toLocalDate    List lt LocalDate gt  dateRangeList8   getDatesRangeJava8 startLocalDate  endLocalDate   System out println dateRangeList8   List lt LocalDate gt  dateRangeList9   getDatesRangeJava8 startLocalDate  endLocalDate   System out println dateRangeList9     The output would be       Mon Dec 20 00 00 00 IST 2010  Tue Dec 21 00 00 00 IST 2010  Wed Dec   22 00 00 00 IST 2010  Thu Dec 23 00 00 00 IST 2010  Fri Dec 24   00 00 00 IST 2010  Sat Dec 25 00 00 00 IST 2010        2010-12-20  2010-12-21  2010-12-22  2010-12-23  2010-12-24    2010-12-25        2010-12-20  2010-12-21  2010-12-22  2010-12-23  2010-12-24    2010-12-25

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You can write a class like it implementing iterator interface    and iterate over it       public class DateIterator implements Iterator lt Date gt   Iterable lt Date gt      private Calendar end   Calendar getInstance     private Calendar current   Calendar getInstance      public DateIterator Date start  Date end          this end setTime end        this end add Calendar DATE  -1        this current setTime start        this current add Calendar DATE  -1         Override  public boolean hasNext           return  current after end         Override  public Date next           current add Calendar DATE  1        return current getTime          Override  public void remove           throw new UnsupportedOperationException           Cannot remove          Override  public Iterator lt Date gt  iterator           return this         and use it like    Iterator lt Date gt  dateIterator   new DateIterator startDate  endDate   while dateIterator hasNext           Date selectedDate   dateIterator  next

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private static void iterateBetweenDates Date startDate  Date endDate        Calendar startCalender   Calendar getInstance        startCalender setTime startDate       Calendar endCalendar   Calendar getInstance        endCalendar setTime endDate        for   startCalender compareTo endCalendar  lt  0            startCalender add Calendar DATE  1                write your main logic here

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Well  you could do something like this using Java 8 s time-API  for this problem specifically java time LocalDate  or the equivalent Joda Time classes for Java 7 and older   for  LocalDate date   startDate  date isBefore endDate   date   date plusDays 1                 I would thoroughly recommend using java time  or Joda Time  over the built-in Date Calendar classes

[java] How to iterate through range of Dates in Java?

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