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Let println be your friend.

Break the equation up into pieces and print out each piece:

System.out.println("secFromMid-secFromMid%3600="+ (secFromMid-secFromMid%3600));

For ease of testing, I suggest you work with...

You do not show what prints out when you do as I suggested. That will tell you what you code is doing.
The formulas you just posted are what you WANT the code to do. But you need to see what the...

Break the statement up into parts and print out the values of all the parts to see why the results is zero

Please edit your post and add code tags around your code to preserve its formatting. Unformatted code is hard to read and understand.
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