CODEWITHSUNDEEP
javadatetimecalendar
OakvilleWork
OakvilleWork

Reputation: 2377

How to calculate the last day of the month?

I am having issues with the calculation of when the next Last Day of the Month is for a notification which is scheduled to be sent.

Here is my code:

RecurrenceFrequency recurrenceFrequency = notification.getRecurrenceFrequency();
Calendar nextNotifTime = Calendar.getInstance();

This is the line causing issues I believe:

nextNotifTime.add(recurrenceFrequency.getRecurrencePeriod(), 
                  recurrenceFrequency.getRecurrenceOffset());

How can I use the Calendar to properly set the last day of the next month for the notification?

Upvotes: 165

Views: 246880

Answers (10)

Przemek Piotrowski
Przemek Piotrowski

Reputation: 7486

java.time.temporal.TemporalAdjusters.lastDayOfMonth()

Using the java.time library built into Java 8, you can use the TemporalAdjuster interface. We find an implementation ready for use in the TemporalAdjusters utility class: lastDayOfMonth.

import java.time.LocalDate;
import java.time.temporal.TemporalAdjusters;

LocalDate now = LocalDate.now(); //2015-11-23
LocalDate lastDay = now.with(TemporalAdjusters.lastDayOfMonth()); //2015-11-30

If you need to add time information, you may use any available LocalDate to LocalDateTime conversion like

lastDay.atStartOfDay(); //2015-11-30T00:00

Upvotes: 75

EduardoMPinto
EduardoMPinto

Reputation: 141

You can also use YearMonth.

Like: 

YearMonth.of(2019,7).atEndOfMonth()
YearMonth.of(2019,7).atDay(1)

See https://docs.oracle.com/javase/8/docs/api/java/time/YearMonth.html#atEndOfMonth--

Upvotes: 12

gokhan
gokhan

Reputation: 667

Kotlin date extension implementation using java.util.Calendar 

fun Date.toEndOfMonth(): Date {
    return Calendar.getInstance().apply {
        time = this@toEndOfMonth
    }.toEndOfMonth().time
}

fun Calendar.toEndOfMonth(): Calendar {
    set(Calendar.DAY_OF_MONTH, getActualMaximum(Calendar.DAY_OF_MONTH))
    return this
}

You can call toEndOfMonth function on each Date object like Date().toEndOfMonth()

Upvotes: 3

AlexR
AlexR

Reputation: 115418

Calendar.getInstance().getActualMaximum(Calendar.DAY_OF_MONTH);

This returns actual maximum for current month. For example it is February of leap year now, so it returns 29 as int.

Upvotes: 389

Kishore Kumar
Kishore Kumar

Reputation: 939

        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
        Date date = sdf.parse("11/02/2016");

        Calendar calendar = Calendar.getInstance();  
        calendar.setTime(date);  

        System.out.println("First Day Of Month : " + calendar.getActualMinimum(Calendar.DAY_OF_MONTH));  
        System.out.println("Last Day of Month  : " + calendar.getActualMaximum(Calendar.DAY_OF_MONTH));

Upvotes: 2

satnam
satnam

Reputation: 11494

Using the latest java.time library here is the best solution:

LocalDate date = LocalDate.now();
LocalDate endOfMonth = date.with(TemporalAdjusters.lastDayOfMonth());

Alternatively, you can do:

LocalDate endOfMonth = date.withDayOfMonth(date.lengthOfMonth());

Upvotes: 10

Safvan Kothawala
Safvan Kothawala

Reputation: 395

Following will always give proper results:

    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.MONTH, ANY_MONTH);
    cal.set(Calendar.YEAR, ANY_YEAR);
    cal.set(Calendar.DAY_OF_MONTH, 1);// This is necessary to get proper results
    cal.set(Calendar.DATE, cal.getActualMaximum(Calendar.DATE));
    cal.getTime();

Upvotes: 21

yetAnotherSE
yetAnotherSE

Reputation: 3268

And to get last day as Date object:

Calendar cal = Calendar.getInstance();
cal.set(Calendar.DATE, cal.getActualMaximum(Calendar.DATE));

Date lastDayOfMonth = cal.getTime();

Upvotes: 40

Bruno
Bruno

Reputation: 94

Look at the getActualMaximum(int field) method of the Calendar object.

If you set your Calendar object to be in the month for which you are seeking the last date, then getActualMaximum(Calendar.DAY_OF_MONTH) will give you the last day.

Upvotes: 3

Mike Deck
Mike Deck

Reputation: 18397

You can set the calendar to the first of next month and then subtract a day.

Calendar nextNotifTime = Calendar.getInstance();
nextNotifTime.add(Calendar.MONTH, 1);
nextNotifTime.set(Calendar.DATE, 1);
nextNotifTime.add(Calendar.DATE, -1);

After running this code nextNotifTime will be set to the last day of the current month. Keep in mind if today is the last day of the month the net effect of this code is that the Calendar object remains unchanged.

Upvotes: 22

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