Daylight saving time

Daylight saving time (DST; also summer time in British English; see Terminology) is the convention of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn.

http://en.wikipedia.org/wiki/Daylight_saving_time

In Java, there are two ways to create days. One method is using Calender object.

Calendar c = Calendar.getInstance();
c.clear();
c.set(Calendar.YEAR,2007);
c.set(Calendar.MONTH,9);
c.set(Calendar.DATE,31);
System.out.println(c.getTime());
c.add(Calendar.DATE,1);
System.out.println(c.getTime());

private List calculateIntervals(DateRange dateRange) {
Date date = dateRange.getStart().getTime();
Calendar c = Calendar.getInstance();
c.clear();
c.setTimeZone(dateRange.getStart().getTimeZone());
c.setTime(dateRange.getStart().getTime());
List dates = new ArrayList();
while (c.getTime().compareTo(dateRange.getEnd().getTime()) <= 0) {
dates.add(c.getTime());
Calendar nextDate = (Calendar) c.clone();
nextDate.add(Calendar.DATE,1);
c = nextDate;
}
return dates;
}

This timezone don't work with daylight saving time. The other way is using Date object.

private List calculateIntervals(DateRange dateRange) {
Date date = dateRange.getStart().getTime();
List dates = new ArrayList();
while (date.compareTo(dateRange.getEnd().getTime()) <= 0) {
dates.add(date);
Date nextDate = (Date) date.clone();
nextDate = DateUtils.addDays(nextDate, 1);
date = nextDate;
}
return dates;
}

This Date object time zone cater with daylight-saving time. In date object->cdate->daylightSaving parameter contains the time in milisecond that should add to the date for daylight-saving changes.