How to Compare two Calendar Objects.

[Seema Shetty]

Hi,
I have problem in comparing these two Calendar objects .I need to know which among the two given Calendar Objects is Latest One or the Greater one.I'am using the code below.Please let me know how to compare these objects using the code below.Please consider the case for two Strings
boolean comparedate = compareDate("2000/01/01 01:01:00","2001/02/21 12:00:00");
public static boolean compareDate(String date1,String date2)
{
boolean retVal1 = false;
boolean retVal2 = false;
int yyyy1 = 0, yyyy2 = 0;
int mm1 = 0, mm2 = 0, dd1 = 0, dd2 = 0, ss1 = 0, ss2 = 0;
int hh1 = 0, hh2 = 0, min1 = 0, min2 = 0;

retVal1 = isDate(date1);

if (retVal1 == true)
{
dd1 = myCalendar.get(myCalendar.DAY_OF_MONTH);
mm1 = myCalendar.get(myCalendar.MONTH) + 1;
yyyy1 = myCalendar.get(myCalendar.YEAR);
hh1 = myCalendar.get(myCalendar.HOUR);
min1 = myCalendar.get(myCalendar.MINUTE);
ss1 = myCalendar.get(myCalendar.SECOND);
}
retVal2 = isDate(date2);
if (retVal2 == true)
{
dd2 = myCalendar.get(myCalendar.DAY_OF_MONTH);
mm2 = myCalendar.get(myCalendar.MONTH) + 1;
yyyy2 = myCalendar.get(myCalendar.YEAR);
hh2 = myCalendar.get(myCalendar.HOUR);
min2 = myCalendar.get(myCalendar.MINUTE);
ss2 = myCalendar.get(myCalendar.SECOND);
}

// long onehr = 60 * 60 * 1000L;

Calendar earlierdate = new GregorianCalendar();
Calendar laterdate = new GregorianCalendar();
earlierdate.set(yyyy1, mm1, dd1,hh1,min1,ss1);
laterdate.set(yyyy2, mm2, dd2,hh2,min2,ss2);
//How should I compare these Objects earlierdate
//laterdate.Which is bigger?

}//end compareDate
Thanks in advance

[Michael Hildner]

Use the SimpleDateFormat to turn Strings into dates, then you can compare the dates. Maybe something like:

import java.text.*;
import java.util.*;
class Test
{
public static void main(String[] args)
{
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
try
{
Date date1 = formatter.parse("2000/01/01 01:01:00");
Date date2 = formatter.parse("2001/02/21 12:00:00");
if (date1.getTime() > date2.getTime())
{
System.out.println("First date is later.");
}
else if (date2.getTime() > date1.getTime())
{
System.out.println("Second date is later.");
}
else if (date1.equals(date2))  // Probably don't need else if,
                               // if you get here, they are equal.
{
System.out.println("Dates are equal");
}
}
catch (ParseException pe)
{
System.out.println("Bad format.");
}
}
}

[ May 22, 2002: Message edited by: Jim Yingst ]

[Art Metzer]

Hi, Seema.
To make your life a little easier, try using SimpleDateFormat and java.util.Calendar's built-in before() method:

import java.text.*;
import java.util.*;
public class When {
    public static final String FORMAT = "yyyy/MM/dd HH:mm:ss";
    public static void main( String[] args ) {
        When w = new When();
        System.out.println( "2000/01/01 01:01:00 is before 2001/02/21 12:00:00:" );
        System.out.println( w.isFirstDateSooner( "2000/01/01 01:01:00",
                                                 "2001/02/21 12:00:00" ) );
    }
    public boolean isFirstDateSooner( String dateString1, String dateString2 ) {
        SimpleDateFormat sdf = new SimpleDateFormat( FORMAT );
        Calendar cal1;
        Calendar cal2;
        Date date1 = null;
        Date date2 = null;
        try {
            date1 = sdf.parse( dateString1 );
            date2 = sdf.parse( dateString2 );
        }
        catch ( ParseException pe ) {
            pe.printStackTrace();
        }
        cal1 = Calendar.getInstance() ;
        cal2 = Calendar.getInstance();
        cal1.setTime( date1 );
        cal2.setTime( date2 );
        return cal1.before( cal2 );
    }
}

Hope this helps,
Art

[Thomas Paul]

Why not just use the before() or after() methods of the Calendar class?
------------------
Moderator of the JDBC Forum

[sai challa]

Originally posted by Seema Shetty:
Hi,
I have problem in comparing these two Calendar objects .I need to know which among the two given Calendar Objects is Latest One or the Greater one.I'am using the code below.Please let me know how to compare these objects using the code below.Please consider the case for two Strings
boolean comparedate = compareDate("2000/01/01 01:01:00","2001/02/21 12:00:00");
public static boolean compareDate(String date1,String date2)
{
boolean retVal1 = false;
boolean retVal2 = false;
int yyyy1 = 0, yyyy2 = 0;
int mm1 = 0, mm2 = 0, dd1 = 0, dd2 = 0, ss1 = 0, ss2 = 0;
int hh1 = 0, hh2 = 0, min1 = 0, min2 = 0;

retVal1 = isDate(date1);

if (retVal1 == true)
{
dd1 = myCalendar.get(myCalendar.DAY_OF_MONTH);
mm1 = myCalendar.get(myCalendar.MONTH) + 1;
yyyy1 = myCalendar.get(myCalendar.YEAR);
hh1 = myCalendar.get(myCalendar.HOUR);
min1 = myCalendar.get(myCalendar.MINUTE);
ss1 = myCalendar.get(myCalendar.SECOND);
}
retVal2 = isDate(date2);
if (retVal2 == true)
{
dd2 = myCalendar.get(myCalendar.DAY_OF_MONTH);
mm2 = myCalendar.get(myCalendar.MONTH) + 1;
yyyy2 = myCalendar.get(myCalendar.YEAR);
hh2 = myCalendar.get(myCalendar.HOUR);
min2 = myCalendar.get(myCalendar.MINUTE);
ss2 = myCalendar.get(myCalendar.SECOND);
}

// long onehr = 60 * 60 * 1000L;

Calendar earlierdate = new GregorianCalendar();
Calendar laterdate = new GregorianCalendar();
earlierdate.set(yyyy1, mm1, dd1,hh1,min1,ss1);
laterdate.set(yyyy2, mm2, dd2,hh2,min2,ss2);
//How should I compare these Objects earlierdate
//laterdate.Which is bigger?

}//end compareDate
Thanks in advance

Hi,
You can try this piece of code for comparing
Date d1=earlierdate.getTime();
Date d2=laterdate.getTime();
int result=d1.compareTo(d2);
if(result<0) //d1 is earlier<br /> if(result==0)//both are equal<br /> if(result>0)//d2 is earlier
[This message has been edited by sai challa (edited April 12, 2001).]

[Pho Tek]

As a corollary; I have a need to parse date strings of the format:
2002/12/14 13:56:01.0
Noticed the precision of the seconds field - with
the additional ".0".
Will this work ? Because I can only find the meta
field "SSS" to represent milliseconds.
yyyy/MM/dd HH:mm:ss.SSS
Thanks
Pho

[Jim Yingst]

Looks like it would work. Have you tried it?

[Pho Tek]

Jim,
I am trying it out as we speak.
I will let the forum know.
Pho

[Pho Tek]

It works.

[Jamie Robertson]

as a late edition, when dealing with string dates I just compare them lexicographically as Strings. The only assumption is that they have to be in fixed format ( i.e. 1999/01/05 and not 1999/1/5 ). This works for all date/time Strings. The only danger is that you will not catch malformed date exceptions.
example:

public static boolean isDate1BeforeDate2( String date1, String date2 )
{
if ( date1.compareTo(date2) < 0 )  // date1 is before date2
{
return true;
}
else
{
return false;  // date1 is equal to or after the date 2
}
}

Any criticisms on my "quick and dirty" method would be appreciated as I us this method regularly.
Jamie

[Jamie Robertson]

as an add on for Pho Tek's milliseconds, it will successfully compare uneven decimal places in the last spot( i.e. xxx.15 compared to xxx.1 )
Jamie
[ May 21, 2002: Message edited by: Jamie Robertson ]

[Jim Yingst]

This works for all date/time Strings
Not all. It won't work for "May 21, 2002", or "05/21/2002", or "21/05/2002". But yes, provided you make sure you're using a date format which orders all information by decreasing significance (and if as you said the format is fixed-width and you don't need to catch invalid formats), this method can work very well. I'm not sure it justifies eight lines of code though:

  public static boolean isDate1BeforeDate2(String date1, String date2)
  {
    return date1.compareTo(date2) < 0;
  }

[ May 21, 2002: Message edited by: Jim Yingst ]

[Jamie Robertson]

Originally posted by Jim Yingst:
This works for all date/time Strings
Not all. It won't work for "May 21, 2002", or "05/21/2002", or "21/05/2002". But yes, provided you make sure you're using a date format which orders all information by decreasing significance (and if as you said the format is fixed-width and you don't need to catch invalid formats), this method can work very well. I'm not sure it justifies eight lines of code though:

  public static boolean isDate1BeforeDate2(String date1, String date2)
  {
    return date1.compareTo(date2) < 0;
  }

[ May 21, 2002: Message edited by: Jim Yingst ]

Does it really matter whether you check for the -1, 0 or 1 result inside the method or outside? I think it is just more intuitively obvious if you return a boolean telling you whether the condition your checking is true or not. It makes the outside code a little cleaner.
just my $.0002
Jamie

[Jim Yingst]

I'm not sure what you're talking about. My version has the exact same usage and behavior as yours does. The check is within the method, which returns a boolean.

[Jamie Robertson]

I missed the < 0 part of the return
Jamie