Best way to find and copy files

Question

If i have a list of 2000 file names and want to find:
if they exist in folder x
then copy to folder y
else
output an error messege to txt file.
What would the most efficient way to do this be? So far i've used listFiles() and put a >HUGE< directory listing into an Array. Then I did a comparison for each file name in the list against the array. I know this cant be the most efficient way. I posted earlier in the board but for some reason NO one answered. Can anyone suggest and easier way to do this? and what is the best way to copy files in java? opening a bufferwriter etc? Essectially, im doing a restore from multiple backup directories to the original directory. Please help me if you can take the time.
Thank you,
jon

Answer 1

If i have a list of 2000 file names and want to
find:
if they exist in folder x
then copy to folder y
else
output an error messege to txt file.
What would the most efficient way to do this be?In a loop just read and write each file. If it does not exist, print an error.
So far i've used listFiles() and put a >HUGE< directory listing into an Array. A directory with a million entries is a HUGE directory, I guess you only have a few thousand.
I wouldn't bother reading the files into memory, you only need 2000 of them.
Then I did a comparison for each file name in the list against the array. The OS will do this for you when you try to open the file, which you will have to do anyway to copy it.
I know this cant be the most efficient way. More efficient way, don't do it at all.
I posted earlier in the board but for some reason NO one answered. Perhaps the problem seemed too obvious.
Can anyone suggest and easier way to do this?
and what is the best way to copy files in java? Copy one at a time.
opening a bufferwriter etc? Read a block of say 64K at a time. No buffers required.
Essectially, im
doing a restore from multiple backup directories to
the original directory. Please help me if you can
take the time.If you are recovering from a backup, the most important thing is ensuring the data is correct and valid, speed is less important. (It is no good if it is fast but corrupt)
Coping 2000 files is going to be only as fast as your drive(s) can handle. How you copy the file is less important.