HELP: Java Programming

Hello,
This may not be the correct place to post my question but I hope someone who knows Java programming can help me out. I use the File.listRoots() method to get all the system roots and I wonder how we know the returned root is a physical hard drive or a removable devices like CD-Rom and floppy drive. I would also like to know how to check if we have permission to read the contents of a folder (what method to use). Thanks in advance.