Date difference

[kri shan]

DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);
String startdate = dateFormat.format(new Date());
String = enddate;
I want to find out the number of days between these two dates,but these two dates are in String format. How can i do that?

[miguel lisboa]

  
import java.util.Calendar;
import java.util.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
 
public class TestaDatas {
 
public int calcula(Date firstDate, Date lastDate) {
 
Calendar last = Calendar.getInstance();
last.setTime(lastDate);
 
Calendar first = Calendar.getInstance();
first.setTime(firstDate);
 
int diference = last.get(Calendar.DAY_OF_YEAR) - first.get(Calendar.DAY_OF_YEAR);
 
return diference;
}
 
public Date converte(String sData) throws ParseException {
return new SimpleDateFormat("dd/MM/yyyy").parse(sData);
}
 
    public static void main(String[] args) throws ParseException {
 
TestaDatas td = new TestaDatas();
 
String sData1 = "1/1/2005";
String sData2 = "31/1/2005";
 
Date d1 = td.converte(sData1);
Date d2 = td.converte(sData2);
 
System.out.println("Diference in days is: \n" 
                    + td.calcula(d1, d2));
}
}

[Jeff Jetton]

Originally posted by miguel lisboa:

int diference = last.get(Calendar.DAY_OF_YEAR) - first.get(Calendar.DAY_OF_YEAR);

Wouldn't that only work as long as the two dates are in the same year? If you set it up like this:

String sData1 = "31/12/2004";
String sData2 = "1/1/2005";

You'd get 364 instead of 1, wouldn't you?

One way to do it, as long as your dates are both after 1/1/1970, is to convert your strings to Date objects, using either DateFormat or SimpleDateFormat like Miguel did. Then use the getTime() method on those dates to get their values in milliseconds. Subtract the two, then divide the result by 86400000 (milliseconds in a day).

- Jeff

[miguel lisboa]

Wouldn't that only work as long as the two dates are in the same year?

that's what i had in mind, but you'r absolutely right!

[kri shan]

Try this code, i am not getting the exact difference....It shows difference between Apr 3 and Apr 4th value is 0. (instead of 1)

 
import java.text.DateFormat;
import java.util.Date;
 
class dateformat{
 public static void main(String args[]) throws Exception{
  DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);
  System.out.println("df.."+ dateFormat);
  String ret = dateFormat.format(new Date());
  System.out.println("ret.."+ ret);
 
  String yesdate = "4/3/05";
 
  Date cudate  = dateFormat.parse(ret);
   System.out.println("cudate.."+ cudate);
 
  DateFormat dateFormat1 = DateFormat.getDateInstance(DateFormat.SHORT);
  Date predate = dateFormat1.parse(yesdate);
  System.out.println("predate.."+ predate);
 
        int difInDays = (int) ((cudate.getTime() - predate.getTime())/(1000*60*60*24));
    System.out.println("difInDays***"+difInDays);
 
 }
}

[kri shan]

Any reply ??

[Steven Bell]

Before you do the difference round each date to the beginning of the day. As long as you don't have to worry about getting dates from different time zones that should work.

[kri shan]

Hi Steven, How can i get the begining of the day??

[kri shan]

I got the exact reult. I used getDateTimeInstance() instead of getDateInstance().

[kri shan]

One more thing, pass the Strign like this..
String yesdate = "3/3/05 0:0 AM, IST";