Familiarize yourself with Appendix B of G&T.

The book contains some bugs since it is quite new; it's worth going through the errata sheet and noting them in your copy; there are probably yet more.

You need not follow the links on these pages; I've listed them individually:
read about inheritance
read more about inheritance

Java interfaces are used within G&T. Aside from the material you read for last time on page 697, here is documentation from another source:
read intro on interfaces
read about interfaces