Solved

Date Parsing

Posted on 2004-10-18
11
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Last Modified: 2010-03-31
Hi,

I think java's date parsing is a little messed up...
Can someone explain why I get a true result in the following code snippet.
Thanks.
------------------------------------------------------------------------------------------

import java.util.*;
import java.text.*;

public class Uptime
{
  public static void main(String []args) throws Exception
  {
   
          String started =       "28 Feb 2004 1:23:45 pm";
          String now =       "28 Feb 2004 1:23:45 am";
   
      SimpleDateFormat df=new SimpleDateFormat("dd MMM yyyy HH:mm:ss aa");

          Date s=df.parse(started,new ParsePosition(0));
          Date n=df.parse(now,new ParsePosition(0));
      System.out.println(s.equals(n)); // prints true...
  }

}
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Question by:BabyFace
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11 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 12341615
Probably because you're telling Java you're using double digits for hours yet you're not in reality. If you move the String format to single figures, it will probably then take into account am/pm and print false
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Accepted Solution

by:
Tommy Braas earned 50 total points
ID: 12341767
Hi BabyFace,

You're specifying to read the time as 24 hour clock, but have added the am/pm field, plus the actual time is in am/pm.

Try the following format:
"dd MMM yyyy h:mm:ss a")


\t
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Expert Comment

by:CEHJ
ID: 12341792
o can you tell me how that answer (posted almost twenty minutes later) is any different from what i've said?
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Expert Comment

by:Tommy Braas
ID: 12341893
CEHJ,
> o can you tell me how that answer (posted almost twenty minutes later)
> is any different from what i've said?
Certainly, you didn't mention that the actual parse string was in 24 hour format. You're not mentioning the conflict between the 24 hour clock and the am/pm field.

\t
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Expert Comment

by:CEHJ
ID: 12341938
>>you didn't mention that the actual parse string was in 24 hour format

>>
you're using double digits for hours yet you're not in reality. If you move the String format to single figures, it will probably then take into account am/pm and print false
>>
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Expert Comment

by:CEHJ
ID: 12342217
!?
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Expert Comment

by:Tommy Braas
ID: 12342402
CEHJ,

So are you saying the 10, 11, 12 are only legal values for the hour field in 24 hour notation?

\t

(being facetious...)
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Expert Comment

by:Tommy Braas
ID: 12342403
BabyFace,

Thank you much! =-)
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Expert Comment

by:CEHJ
ID: 12342451
>>So are you saying the ..

I don't understand your comment, but i do understand that you've simply paraphrased the answer i gave:

>>You're specifying to read the time as 24 hour clock
==
>>you're using double digits for hours

and
>>
Try the following format:
"dd MMM yyyy h:mm:ss a")
>>
==
>> If you move the String format to single figures
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Expert Comment

by:Tommy Braas
ID: 12342542
CEHJ,
> >>You're specifying to read the time as 24 hour clock
> ==
> >>you're using double digits for hours

NOT the same thing. "HH" parses as 24 hour clock (which is what the asker was using), "hh" or "h" denotes 12 hour clock. Whether you use one or two 'h' is of NO consequence, same thing goes for the 'a'

\t
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Expert Comment

by:CEHJ
ID: 12342589
>>NOT the same thing.

That's certainly what i meant by it
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