I/O in Java® 2 SDK
I/O in Java 2 SDK contains a number of significant changes to
java.io.File, making it a true abstract representation of file and directory pathnames. Both the specification and implementation of this class have been thoroughly revised, giving support for new features such as temporary files, conversion of abstract pathnames to URL's, comparability, and access to additional file attributes.
For completeness, a discussion of the JDK 1.1 I/O changes can be found here as well:
I/O Guide to features introduced in JDK 1.1
Additional I/O reference material