Hi,

1. You use java.io.File API to read the files
2. Do your validation upon reading the files - based on the size of the
files, you can read them line by line and do your validations.
3. Use try catch blocks for exceptions (It' be IOException mostly)
4. Declare your own exceptions if you want the caller to be known of
validation errors
5. Use JDBC API to talk to the database.

-cheers,
Manish