first date and last date of month

[siraj baig]

hi,
i have a string date
String date = "06/26/2006"
how can i get the first date and last date of this date.

Thanks.

[Vijitha Kumara]

You can use the Calender class to do this.

Calendar c = Calendar.getInstance();    
c.set(2008,3,1); //------>
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
    
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
System.out.println(sdf.format(c.getTime()));

you will get the output - 30/04/2008

------> here, put the year and (month-1) to get the last date of the month.

Regards
[ July 08, 2008: Message edited by: Vijitha Kumara ]

[subodh gupta]

the code you have posted is returning the last day of the next month e.g. if i am passing the Januay date it gives the last date of the Feb

[fred rosenberger]

January is (i believe) 0, not 1.

[Rob Spoor]

So true. That's why you should use Calendar.JANUARY etc instead.

[subodh gupta]

Thanks All,

I should have gone through src/api before posting.

[Sudharshan Reddy Ch]

Explained in the below post.
Get first date and last date in current month

[Rob Spoor]

No offense, but I have to say that class is a mess. First of all, you use a lot of formatting + parsing to get rid of the day, just to set it afterwards. Second, your getLastDay method does not take into account daylight savings time, when one day can have 23 hours instead of 24. Thirdly, your if-statement in the last method is just nasty. A switch would have made more sense:

    public int getLastDayOfMonth(Date date)
    {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH) + 1;
        int mapLastDay = 0;

        switch (month)
        {
            case 1: // fall through
            case 3: // fall through
            case 5: // fall through
            case 7: // fall through
            case 8: // fall through
            case 10: // fall through
            case 12:
                mapLastDay = 31;
                break;
            case 4: // fall through
            case 6: // fall through
            case 9: // fall through
            case 11:
                mapLastDay = 30;
                break;
            case 2:
                if (0 == year % 4 && 0 != year % 100 || 0 == year % 400)
                {
                    mapLastDay = 29;
                }
                else
                {
                    mapLastDay = 28;
                }
                break;
        }
        return mapLastDay;
    }

That said, all your methods could have been written using only Date and Calendar; no formatting and re-parsing, just the final formatting:

public class SimpleDate
{
    public SimpleDate()
    {
    }

    public static void main(String args[]) throws Exception
    {
        SimpleDate simpleDate = new SimpleDate();
        String firstDate = simpleDate.getFirstDay(new Date());
        String lastDate = simpleDate.getLastDay(new Date());
        System.out.println("First Date: " + firstDate);
        System.out.println("Last Date: " + lastDate);
        // To get first day and last day of the month
        //Sunday = 1, Saturday = 7
        Calendar calendar = new GregorianCalendar();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        Date dateFirst = sdf.parse(firstDate);
        calendar.setTime(dateFirst);
        System.out.println("First Day: " + calendar.get(Calendar.DAY_OF_WEEK));
        Date dateLast = sdf.parse(lastDate);
        calendar.setTime(dateLast);
        System.out.println("Last Day: " + calendar.get(Calendar.DAY_OF_WEEK));
    }

    public String getFirstDay(Date d) throws Exception
    {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(d);
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        Date dddd = calendar.getTime();
        SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy/MM/dd");
        return sdf1.format(dddd);
    }

    public String getLastDay(Date d) throws Exception
    {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(d);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        Date dddd = calendar.getTime();
        SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy/MM/dd");
        return sdf1.format(dddd);
    }

    public String getDate(Date d)
    {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM");
        return sdf.format(d);
    }

    public int getLastDayOfMonth(Date date)
    {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
    }
}

Not only is it shorter (1 line each for the first two methods, and don't get me started on the last one), it is also more robust (the daylight savings time thingy, Calendar has proven itself*) and easier to understand.


* A lot of people recommend using Joda time over Calendar. I feel that their motivations are more based on usability than Calendar not working.

[Sudharshan Reddy Ch]

Thanks for the correction Rob!!

[Rob Spoor]

You're welcome

And don't be hard done by my comments. I've written code a lot worse than that even during the latter stages of getting my degree The thing is, you learn by practice and experience, and from corrections by others. I still learn new methods and classes in the API quite regularly.