Date need to be advance to next month

[SaurabhSri Sri]

Hi All,

From a page user enters Start date and End date. A java program returns one month advance of both dates as "Start date || End date". e.g

Suppose, Start Date = 04-06-2008, End Date = 10-06-2008
Then return value = 04-07-2008 || 10-07-2008

Now, a problem comes when I have select first day of month as start date and last day as end date -

Start Date = 01-06-2008, End Date = 30-06-2008
The return value is = 01-07-2008 || 30-07-2008
But it should return, 01-07-2008 || 31-07-2008 because July is having 31 days.
My code is -

    
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
 
public class MainTest 
{
private static String calDate(String startPeriod, String endPeriod)
{ 

  DateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");
  SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
  
      String newStartPeriod = null;
      String newEndPeriod = null;
      
      try 
      {
    Date startdate = (Date)formatter.parse(startPeriod); ;
    Date enddate = (Date)formatter.parse(endPeriod); 
    
    Calendar calstart=Calendar.getInstance();
Calendar calend=Calendar.getInstance();

calstart.setTime(startdate);
calend.setTime(enddate);
    
    calstart.add(Calendar.MONTH, 1);
calend.add(Calendar.MONTH, 1);

newStartPeriod = sdf.format(calstart.getTime());
newEndPeriod = sdf.format(calend.getTime());
    }
      catch(ParseException ex)
      {
    System.out.println("Exception :: " + ex);
    }
      return (newStartPeriod + " || " + newEndPeriod);
}

public static void main(String[] args) 
{
String startPeriod = "01-06-2008";
      String endPeriod = "30-06-2008";
      
      String res = calDate(startPeriod, endPeriod);
      System.out.println("Result :: " + res);
}
}

Thanks in advance for your help.

[Martijn Verburg]

Hmm, interesting problem, I ran this locally in my debugger and internally the JDK calls a method which corrects for the other way (e.g. It corrects the day if you were going from the 31st of Jan to 28th of Feb) but it doesn't appear to cover your case... (I tried JDK 1.5 and 1.6).

I'm no date and calendar guru so hopefully someone else can enlighten..

Cheers,
Martijn

[Jesper de Jong]

Well, the result that you get sounds logical to me - one month after June 30th is July 30th, isn't it?

You should think carefully about what you want, and then write Java code to do it. Here is a question to get you thinking: Suppose the user enters 29-06-2008. What should the result be; 29-07-2008? And if the user enters 30-06-2008, you want the result to be 31-07-2008? So the result can never be 30-07-2008?

[Martijn Verburg]

Originally posted by Jesper Young:
Well, the result that you get sounds logical to me - one month after June 30th is July 30th, isn't it?

You should think carefully about what you want, and then write Java code to do it. Here is a question to get you thinking: Suppose the user enters 29-06-2008. What should the result be; 29-07-2008? And if the user enters 30-06-2008, you want the result to be 31-07-2008? So the result can never be 30-07-2008?

Yeah I was just thinking about this on the way back from Lunch, 'of course' the API wouldn't just bump you up to the last day of the month, otherwise you'd never be able get 30-07-2008 <smacks head>.

@Original poster: So as Jesper says you'll have to treat the last day of the month as a special case (if that's what you're truly intending).