How to iterate through range of Dates in Java?

Question

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.

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.

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 -> 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);

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);
}