CODEWITHSUNDEEP
javadatecalendardayofweek
Adil Bhatty
Adil Bhatty

Reputation: 17340

Get next week and previous week staring and ending dates in java

I want to get the starting and ending dates of a week for example

2012-05-06 to 2012-05-12
2012-05-13 to 2012-05-19

The code I have written is 

currWeekCalender.add(Calendar.WEEK_OF_YEAR, 1);

    String dateStart =  currWeekCalender.get(Calendar.YEAR) + "-" + addZero((currWeekCalender.get(Calendar.MONTH) + 1)) + "-" + addZero(currWeekCalender.getFirstDayOfWeek());
    currWeekCalender.add(Calendar.DAY_OF_MONTH,7);
    String dateEnd =  currWeekCalender.get(Calendar.YEAR) + "-" + addZero((currWeekCalender.get(Calendar.MONTH) + 1)) + "-" + addZero(currWeekCalender.get(Calendar.DAY_OF_MONTH));

but the results are not correct, also I want previous weeks date.

Thanks

Upvotes: 3

Views: 21930

Answers (4)

Arvind Kumar Avinash
Arvind Kumar Avinash

Reputation: 79085

java.time

In March 2014, Java 8 introduced the modern, java.time date-time API which supplanted the error-prone legacy, java.util date-time API. Any new code should use the java.time API. If you are receiving an instance of java.util.Date, convert it tojava.time.Instant, using Date#toInstant and derive other date-time classes of java.time from it as per your requirement.

The first day of the week is locale-specific e.g.

DayOfWeek firstDowUk = WeekFields.of(Locale.UK).getFirstDayOfWeek();
DayOfWeek firstDowUs = WeekFields.of(Locale.US).getFirstDayOfWeek();
System.out.println(firstDowUk); // MONDAY
System.out.println(firstDowUs); // SUNDAY

So, the date on the first day of the week will also differ e.g.

// ZoneId.systemDefault() returns the ZoneId set to the JVM executing the code
// Change it as per your requirement e.g. ZoneId.of("Europe/London")
LocalDate today = LocalDate.now(ZoneId.systemDefault());
LocalDate dateOnFirstDowUk = today.with(TemporalAdjusters.previousOrSame(firstDowUk));
LocalDate dateOnFirstDowUs = today.with(TemporalAdjusters.previousOrSame(firstDowUs));
System.out.println(dateOnFirstDowUk);
System.out.println(dateOnFirstDowUs);

Use LocalDate#minusWeeks to go back to a date by specified number of weeks e.g.

// Go back by one week
System.out.println(dateOnFirstDowUk.minusWeeks(1));
System.out.println(dateOnFirstDowUs.minusWeeks(1));

Demo:

public class Main {
    public static void main(String[] args) {
        DayOfWeek firstDowUk = WeekFields.of(Locale.UK).getFirstDayOfWeek();
        DayOfWeek firstDowUs = WeekFields.of(Locale.US).getFirstDayOfWeek();
        System.out.println(firstDowUk); // MONDAY
        System.out.println(firstDowUs); // SUNDAY

        // ZoneId.systemDefault() returns the ZoneId set to the JVM executing the code
        // Change it as per your requirement e.g. ZoneId.of("Europe/London")
        LocalDate today = LocalDate.now(ZoneId.systemDefault());
        LocalDate dateOnFirstDowUk = today.with(TemporalAdjusters.previousOrSame(firstDowUk));
        LocalDate dateOnFirstDowUs = today.with(TemporalAdjusters.previousOrSame(firstDowUs));
        System.out.println(dateOnFirstDowUk);
        System.out.println(dateOnFirstDowUs);

        // Go back by one week
        System.out.println(dateOnFirstDowUk.minusWeeks(1));
        System.out.println(dateOnFirstDowUs.minusWeeks(1));
    }
}

Online Demo

Learn more about the modern Date-Time API from Trail: Date Time.

Upvotes: 1

freedev
freedev

Reputation: 30077

Java 8 version

This prints previous 10 weeks

final ZonedDateTime input = ZonedDateTime.now();

for(int i = 1; i < 10; i++) {
    final ZonedDateTime startOfLastWeek = input.minusWeeks(i).with(DayOfWeek.MONDAY);
    System.out.print(startOfLastWeek.format(DateTimeFormatter.ISO_LOCAL_DATE));
    final ZonedDateTime endOfLastWeek = startOfLastWeek.plusDays(6);
    System.out.println(" - " + endOfLastWeek.format(DateTimeFormatter.ISO_LOCAL_DATE));
}

Upvotes: 2

ogniwo100
ogniwo100

Reputation: 51

Hello to all coders :)

I work on little app to dive some data from database. To calculate previous weeks start and end date i use this code:

// Calendar object
Calendar cal = Calendar.getInstance();

// "move" cal to monday this week (i understand it this way)
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);

// calculate monday week ago (moves cal 7 days back)
cal.add(Calendar.DATE, -7);
Date firstDateOfPreviousWeek = cal.getTime();

// calculate sunday last week (moves cal 6 days fwd)
cal.add(Calendar.DATE, 6);
Date lastDateOfPreviousWeek = cal.getTime();

Hope, that helps.

Upvotes: 4

Mike Samuel
Mike Samuel

Reputation: 120516

Your problem is that getFirstDayOfWeek() returns the first day of the week; e.g., Sunday in US, Monday in France. It does not return a day of the month. See javadoc.

The first day in a month that is the start of the week is (in pseudo-code)

((7 + (firstDayOfWeek - dayOfWeek(firstOfMonth))) % 7) + 1

You can translate that into java.util.Calendar code if you like, but I would suggest using Joda time instead.

also I want previous weeks date.

Just subtract seven days maybe using add

currCalendar.add(Calendar.DAY_OF_MONTH, -7)

This may involve underflow, but add deals with that.

add(f, delta)

adds delta to field f. This is equivalent to calling set(f, get(f) + delta) with two adjustments:

Add rule 1. The value of field f after the call minus the value of field f before the call is delta, modulo any overflow that has occurred in field f. Overflow occurs when a field value exceeds its range and, as a result, the next larger field is incremented or decremented and the field value is adjusted back into its range.

Upvotes: 2

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