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Ibrahim Ates
Ibrahim Ates

Reputation: 385

How do find day number(integer) of last day in the current month

I have specific date and i want to find last day number(integer) of month. I am using following code but always return current of date.

    DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

    Date date = (Date) sdf.parse(year+"-"+(month<10?("0"+month):month)+"-01");


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

    calendar.add(Calendar.MONTH, 1);
    calendar.set(Calendar.DAY_OF_MONTH, 1);
    calendar.add(Calendar.DATE, -1);

    Date dt = (Date) calendar.getTime(); -> dt is return current date always

example: my date = 2018/04/30 and i want to find 30.

I couldnt find answer at site.

Thnx

Upvotes: 1

Views: 524

Answers (5)

Andreas
Andreas

Reputation: 159270

If using Java 8 (or higher), don't use Calendar. If using Java 6 or 7, you might want to consider using the ThreeTen Backport. In either case, use the Java Time API.

Using Java Time

Since input is int year and int month, use YearMonth.

To find last day number of month, call lengthOfMonth().

To get the date at the end of month, call atEndOfMonth().

Demo

int year = 2020;
int month = 2;

int lastDay = YearMonth.of(year, month).lengthOfMonth();
System.out.println(lastDay);

LocalDate date = YearMonth.of(year, month).atEndOfMonth();
System.out.println(date);

Output

29
2020-02-29

Using Joda-Time

If you don't have Java 8, and already use Joda-Time, do it this way:

Demo

int year = 2020;
int month = 2;

int lastDay = new LocalDate(year, month, 1).dayOfMonth().getMaximumValue();
System.out.println(lastDay);

LocalDate date = new LocalDate(year, month, 1).dayOfMonth().withMaximumValue();
System.out.println(date);

Output

29
2020-02-29

Using Calendar

If you insist on using Calendar, call getActualMaximum(Calendar.DAY_OF_MONTH) as also mentioned in other answers.

Since input is int year and int month, don't build and parse a string, just set Calendar fields directly. Note that "month" in Calendar is zero-based.

Demo

int year = 2020;
int month = 2;

Calendar calendar = Calendar.getInstance();
calendar.clear();
calendar.set(year, month - 1, 1);
int lastDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);

calendar.set(Calendar.DAY_OF_MONTH, lastDay);
Date date = calendar.getTime();

System.out.println(lastDay);
System.out.printf("%tF%n", date);

Output

29
2020-02-29

Upvotes: 4

Adrian Shum
Adrian Shum

Reputation: 40076

First, how are you getting the year to be used?

it should be simple by using Java Time LocalDate:

import java.time.*;
import static java.time.Month.*;
import static java.time.temporal.TemporalAdjusters.*;
import static java.time.temporal.ChronoField.*;

int lastDay = LocalDate.now()   // or whatever date you want
                  .with(Month.of(yourMonth))
                  .with(lastDayOfMonth())
                  .get(DAY_OF_MONTH);

 // or, if you have year and month, and want to find the corresponding last day
int lastDay = LocalDate.of(yourYear, yourMonth, 1)
                  .with(lastDayOfMonth())
                  .get(DAY_OF_MONTH);

Upvotes: 1

NiVeR
NiVeR

Reputation: 9806

You can use calendar for that, like this:

calendar.getActualMaximum(Calendar.DAY_OF_MONTH);

Or, if you have joda, which is usually better:

DateTime d = new DateTame(dt);
d.dayOfMonth().getMaximumValue();

Upvotes: 1

J.cui
J.cui

Reputation: 11

Calendar calendar =Calendar.getInstance();
calendar.set(Calendar.DATE, 1); 
calendar.roll(Calendar.DATE, -1); 
int lastDate=calendar.get(Calendar.DATE);

Upvotes: 1

Jigar Joshi
Jigar Joshi

Reputation: 240996

have specific date and i want to find last day number(integer) of month

getActualMaximum() is what you are looking for here.

Calendar cal = Calendar.getInstance();
cal.setTime(parsedDate);
cal.getActualMaximum(Calendar.DAY_OF_MONTH);

Upvotes: 3

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