How to overwrite a file?

Dear Sir,
I'm writing a program which read a txt file (e.g.infile.txt) and before quit the program, I need to rename the file to infile.old and create another infile.txt. I used file.renameTo(newfile) to rename the file. However, when I run the program the 2nd time, I found that the infile.txt cannot be rename since the infile.old already exist (that means the infile.old cannot be overwirte).
Question 1:
In the program, I need to find whether an infile.old already exist. Which method can be used and what's the synthx?
Question 2:
If the program check that an infile.old already exist, do I need to delete it (before doing the rename) or use another method to overwrite it?
Thanks a lot!

Question 1:
In the program, I need to find whether an infile.old
already exist. Which method can be used and what's
the synthx?Look at the api for the File class it should be pretty clear what method to use.
Question 2:
If the program check that an infile.old already exist,
do I need to delete it (before doing the rename) or
use another method to overwrite it? I would delete the file first, if you just overwrite it and your new data is smaller than the current data in the file, you will have leftovers from the old data at the end of your new data.

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