I am trying to calculate the Date object of the last Monday at 12 am. Here is my code:

Calendar calendar = Calendar.getInstance()
        calendar.setTime(currentDate)

        Integer dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK)
        if (dayOfWeek > Calendar.MONDAY) {
            Integer daysDifferenceFromMonday = dayOfWeek - Calendar.MONDAY
            calendar.add(Calendar.DATE, -daysDifferenceFromMonday)
        } else if (dayOfWeek < Calendar.MONDAY) {
            // it means that we are on Sunday and we need last sunday
            Integer daysDifferenceFromMonday = 7 - (Calendar.MONDAY - dayOfWeek)
            calendar.add(Calendar.DATE, -daysDifferenceFromMonday)
        }

        calendar.set(Calendar.MILLISECOND, 0)
        calendar.set(Calendar.SECOND, 0)
        calendar.set(Calendar.MINUTE, 0)
        calendar.set(Calendar.HOUR, 0)
        Date toDate = calendar.getTime()

As you can see, I am setting the hour to 0. But, calendar.getTime() gives me 12:00:00.

Here is the debugger screenshot.

What am I doing wrong? This thing is very strait-forward.

I am trying to calculate the Date object of the last Monday at 12 am. Here is my code:

Calendar calendar = Calendar.getInstance()
        calendar.setTime(currentDate)

        Integer dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK)
        if (dayOfWeek > Calendar.MONDAY) {
            Integer daysDifferenceFromMonday = dayOfWeek - Calendar.MONDAY
            calendar.add(Calendar.DATE, -daysDifferenceFromMonday)
        } else if (dayOfWeek < Calendar.MONDAY) {
            // it means that we are on Sunday and we need last sunday
            Integer daysDifferenceFromMonday = 7 - (Calendar.MONDAY - dayOfWeek)
            calendar.add(Calendar.DATE, -daysDifferenceFromMonday)
        }

        calendar.set(Calendar.MILLISECOND, 0)
        calendar.set(Calendar.SECOND, 0)
        calendar.set(Calendar.MINUTE, 0)
        calendar.set(Calendar.HOUR, 0)
        Date toDate = calendar.getTime()

As you can see, I am setting the hour to 0. But, calendar.getTime() gives me 12:00:00.

Here is the debugger screenshot.

What am I doing wrong? This thing is very strait-forward.

• java
• date
• groovy

• 4 "What am I doing wrong?" - using these outdated classes like Date and Calendar, outdated in Java 8 (10 years ago) - better use classes from the java.time package -- and posted code is not valid Java ?!? – user85421 Commented Nov 18, 2024 at 23:12
• 1 and maybe using HOUR_OF_DAY is better than HOUR (unless also [re-]setting AM_PM, otherwise you risk it being PM) (( but I would still prefer the newer java.time classes )) – user85421 Commented Nov 18, 2024 at 23:24
• 3 You should be doing something like: LocalDate lastMonday = LocalDate.now().with(TemporalAdjusters.previous(DayOfWeek.MONDAY));System.out.println("Start of last Monday was: " +lastMonday.atStartOfDay()); – g00se Commented Nov 18, 2024 at 23:27
• 1 @user85421 It didn't stop, where it stopped is simply no in the screenshot. HOUR_OF_DAY helped. Thank you – Alex A. Commented Nov 18, 2024 at 23:32
• 1 @g00se OOOOHhhhh!!! This is awesome!! Thank you! – Alex A. Commented Nov 19, 2024 at 1:16

1 Answer 1

Just in case anyone is interested in the solution. I ended up doing something like this:

LocalDateTime rangeEnd = LocalDate.now().with(TemporalAdjusters.previousOrSame(DayOfWeek.MONDAY)).atStartOfDay()
LocalDateTime rangeStart = rangeEnd.minusWeeks(1)

[
       from: DateUtils.localDateTimeToDate(rangeStart),
       to: DateUtils.localDateTimeToDate(rangeEnd)
]

Basically, a single line answers the original question :)