[Very Urgent] Need help calculating difference between two dates

[rustix]

I'm trying to write a code to display the current day and time, then accept two dates from the user and display the difference between the two dates. To display the current date and time, I've used the SimpleDateFormatter library but I'm having difficulty calculating the difference between two dates. Could someone please help me with this?

Below is my code so far

import java.util.Date;
import java.util.Scanner;
import java.text.SimpleDateFormat;

public class DateFormatter {
	public void displayNow()
	{
		Date todaysDate = new Date();
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");

		String formattedDate = formatter.format(todaysDate);
		System.out.println("Today's date and time is: "+formattedDate);
	}

	public void calculateDifference(Date startDate, Date endDate)
	{
		/* This is whre i need help! */
	}

	public static void main(String[] args)
	{
		DateFormatter df = new DateFormatter();
		Scanner sc = new Scanner(System.in);
		
		df.displayNow();
		
		System.out.println("Please enter a date: ");
		String date1 = sc.next();
		System.out.println("Please enter another date: ");
		String date2 = sc.next();
	}
}

The methods displayNow() and calculateDifference(Date startDate, Date endDate) are essential and cannot be skipped out.

[masijade]

Calendar, it's setTime, getTime, and add methods, a counter, and a while loop. Check the API for Calendar and attempt something. Once you have something, post it, and we can help you correct it, but we are not going to do it for you.

[rustix]

for the record, i didn't ask anyone to do it for me!

[masijade]

And

for the record

I didn't say you did, I just gave the warning that we wouldn't.

[Norm]

public void calculateDifference(Date startDate, Date endDate)

It seems like the above mentioned method should return something. If not, what does it do then?

[fishtoprecords]

In recent versions, the use of Calendar objects instead of Date objects is preferred for uses like this.

But in either class, the actual date/time value is kept in a long, you can just get the long, and subtract them to get the time difference, and then use an appropriate function (or even just division and mod functions) to convert the milliseconds to days, months, years.

Get the arithmetic right first, and then use DateFormat to display it.

[masijade]

In recent versions, the use of Calendar objects instead of Date objects is preferred for uses like this.

But in either class, the actual date/time value is kept in a long, you can just get the long, and subtract them to get the time difference, and then use an appropriate function (or even just division and mod functions) to convert the milliseconds to days, months, years.

Get the arithmetic right first, and then use DateFormat to display it.

Don't forget to account for the time skew that leads to the leap years. (And that is the exact reason why Calendar is preferred, now. The programmer doesn't need to bother with it.)

[suprabha]

Hi all,
I need java code to get differnce between two given dates

[masijade]

So write some.

Hint:

Calendar and it's add method. (then you start to hammer out the hour/minute/second differences after you have the "days" difference)

[mbnumba6]

Yea I have the same exact question as this thread. The only thing is I want to use the "this" and "that" keyword of java, that is if that is even possible. If you need my whole code for my program I will give it to you.

Here is my method



/**
*To get the difference of number of days
*in between two dates using "this" and "that"
* @return diffrenece between two dates
*/

 if((month >=1) && (month <=12) &&(day > 0) && (day <= daysInMonth(month)))
               {
                   
                   currentDate = daysInMonth(month);
                   currentDate = this - currentDate ;    
                   
               }    
                   
               else 
               {
               currentDate = 0;
               }
               
               return this;
               
               
          }

[helloworld111]

Have a look at this page:
http : // forums.sun.com/thread.jspa?threadID=488668&forumID=4

There is some code to calculate date/time differences

[neeraj.singh]

get the day, month, and year of the both dates in int format, and then you can easily compare starting from yr.

eg:
if(yr1==y2)
if(m1==m2)
if(d1==d2)
isSameDate = true;

[saurabh1073]

import java.util.*;



public class DiffDate {
public static void main(String[] av) {

Date d1=new Date();
Date d2=new Date("2009/03/11");
int difInDays = (int) ((d2.getTime() - d1.getTime())/(1000*60*60*24));
System.out.println("diffindays"+difInDays);


}
}
Hi. Try to use in this way to find out the difference between two dates.

[masijade]

Just delving further and further into misinformation.

[mbnumba6]

hmm. Never mind I got mines to work. The only problem is it wont work right if the month has 31, 29, or 28 days in it.

public int differnceInDate(int day, int month, int year)
           {
               int currentDay;
               int currentMonth;
               int currentYear;
               
               
               
               if((month >=1) && (month <=12) &&(day > 0) && (day <= daysInMonth(month)))
               {
                   
                   currentDay = calendarDay - day;
                   
                   
                   
                   currentMonth = calendarMonth - month;  
                   currentDay = currentMonth * 30 + currentDay;
                   
                   
                   
                   currentYear = calendarYear - year; 
                   currentDay = currentYear * 365 + currentDay;
                   
                   
               }    
                   
               else 
               {
               currentDay = 0;
               }
               
               return currentDay;
               
               
          }

[masijade]

It's like talking to a wall.

[neeraj.singh]

please refer to the saurabh's post...
thats the perfect solutions

[Steve11235]

Please disregard this post. The logic is incorrect...

Rustix, after reading down the posts and looking at the API, this is not a simple operation. For whatever reason, Calendar does not provide a difference() method for doing this calculation.

The first question is: How do you want to express this difference?

If you just want days, etc., then use Saurabh's method.

If you want years, month, days, etc., then you need to use GregorianCalendar, which is the only concrete implementation of Calendar, and the fact that a millisecond value of 0 corresponds to 1970.01.01. Note also GregorianCalendar normally defaults to the current time zone, while Date uses GMT. The GregorianCalendar must be forced to use GMT, or you will end up a day off.

Warning: Always use a positive difference. How you represent that the difference is negative is up to you. I did *not* include any code to check for pDate1 >= pDate2.

package test;

import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;

public class DateDifferenceTest {
	public static void main(String[] args) {
		final Date date1, date2;
		date1 = (new GregorianCalendar(2008,
		    12,
		    31)).getTime();
		date2 = (new GregorianCalendar(2007,
		    11,
		    30)).getTime();
		System.out.println(dateDifference(date1,
		    date2));
	}

	public static String dateDifference(final Date pDate1,
	    final Date pDate2) {
		final String diffString;
		long difference = 0;
		GregorianCalendar gc = null;
		gc = new GregorianCalendar();
		gc.setTimeZone(TimeZone.getTimeZone("GMT"));
		gc.setTimeInMillis(pDate1.getTime()
		    - pDate2.getTime());
		diffString = (gc.get(GregorianCalendar.YEAR) - 1970)
		    + "."
		    + (gc.get(GregorianCalendar.MONTH))
		    + "."
		    + (gc.get(GregorianCalendar.DAY_OF_MONTH) - 1);
		return diffString;
	}
}

[masijade]

If you do setTime(Date) with the Calendar, you do not end up a day off. And using getTime() on the Calendar to compare to the original date you are also not a "day off", as that returns a Date object. Use two Calendars for start and end date, and the point becomes completely moot.

[Steve11235]

Apparently, you didn't test the code I provided. You are correct in saying "not a day off", it is more like, the time zone adjustment off. However, for those of us west of the Prime Meridian, that puts us a few hours early. Since "dates" are normally entered without minutes, that puts the calendar several hours early, resulting in a value that, when truncated to year.month.day, is a day off.

The point is not moot; I found it because the results were a day off. I corrected it by setting the calendar time zone to GMT.