In what way do the files differ? Surely, if the overall size is different, then there must be at least one file inside of it that has a different size?
The length is same. I tested it by printing the length in the standard output.
I used a folder comparison software to find exactly where things went wrong. It showed that the content of jar file was a mismatch. So I extracted the jars and then compared it again but the extracted files did not have any difference.
So I guess the problem lies on the archiving task of ant i.e <jar>. So Is there any way by which I can get consistent ouput for the same.
You need to identify exactly what is different about them.
If the difference is the time the file was created, then you can never make them exactly the same.
Some file/folder compare softwares include the time/date in their compare. Some of these software allows to exclude in the compare process, the time/date factor.