The Java programming language was originally called Oak, and was
designed for use in embedded consumer-electronic applications by James
Gosling. After several years of experience with the language, and
significant contributions by Ed Frank, Patrick Naughton, Jonathan
Payne, and Chris Warth it was retargeted to the Internet, renamed, and
substantially revised to be the language specified here. The final
form of the language was defined by James Gosling, Bill Joy, Guy
Steele, Richard Tuck, Frank Yellin, and Arthur van Hoff, with help
from Graham Hamilton, Tim Lindholm, and many other friends and
colleagues.

The Java programming language is a general-purpose concurrent
class-based object-oriented programming language, specifically
designed to have as few implementation dependencies as possible. It
allows application developers to write a program once and then be able
to run it everywhere on the Internet.

This book attempts a complete specification of the syntax and
semantics of the language. We intend that the behavior of every
language construct is specified here, so that all implementations will
accept the same programs. Except for timing dependencies or other
non-determinisms and given sufficient time and sufficient memory
space, a program written in the Java programming language should
compute the same result on all machines and in all implementations.

We believe that the Java programming language is a mature language,
ready for widespread use. Nevertheless, we expect some evolution of
the language in the years to come. We intend to manage this evolution
in a way that is completely compatible with existing applications. To
do this, we intend to make relatively few new versions of the
language, and to distinguish each new version with a different
filename extension. Compilers and systems will be able to support the
several versions simultannously, with complete compatibility.

Much research and experimentation with the Java platform is already
underway. We encourage this work, and will continue to cooperate with
external groups to explore improvements to the language and
platform. For example, we have already received several interesting
proposals for parameterized types. In technically difficult areas,
near the state of the art, this kind of research collaboration is
essential.

We acknowledge and thank the many people who have contributed to this
book through their excellent feedback, assistance and encouragement:

Particularly thorough, careful, and thoughtful reviews of drafts were
provided by Tom Cargill, Peter Deutsch, Paul Hilfinger, Masayuki Ida,
David Moon, Steven Muchnick, Charles L. Perkins, Chris Van Wyk, Steve
Vinoski, Philip Wadler, Daniel Weinreb, and Kenneth Zadeck. We are
very grateful for their extraordinary volunteer efforts.

We are also grateful for reviews, questions, comments, and suggestions
from Stephen Adams, Bowen Alpern, Glenn Ammons, Leonid Arbuzov, Kim
Bruce, Edwin Chan, David Chase, Pavel Curtis, Drew Dean, William
Dietz, David Dill, Patrick Dussud, Ed Felten, John Giannandrea, John
Gilmore, Charles Gust, Warren Harris, Lee Hasiuk, Mike Hendrickson,
Mark Hill, Urs Hoelzle, Roger Hoover, Susan Flynn Hummel, Christopher
Jang, Mick Jordan, Mukesh Kacker, Peter Kessler, James Larus, Derek
Lieber, Bill McKeeman, Steve Naroff, Evi Nemeth, Robert O'Callahan,
Dave Papay, Craig Partridge, Scott Pfeffer, Eric Raymond, Jim Roskind,
Jim Russell, William Scherlis, Edith Schonberg, Anthony Scian, Matthew
Self, Janice Shepherd, Kathy Stark, Barbara Steele, Rob Strom, William
Waite, Greg Weeks, and Bob Wilson. (This list was generated
semi-automatically from our E-mail records. We apologize if we have
omitted anyone.)

The feedback from all these reviewers was invaluable to us in
improving the definition of the language as well as the form of the
presentation in this book. We thank them for their diligence. Any
remaining errors in this book-we hope they are few-are our
responsibility and not theirs.

We thank Francesca Freedman and Doug Kramer for assistance with
matters of typography and layout. We thank Dan Mills of Adobe Systems
Incorporated for assistance in exploring possible choices of
typefaces.

Many of our colleagues at Sun Microsystems have helped us in one way
or another. Lisa Friendly, our series editor, managed our relationship
with Addison-Wesley. Susan Stambaugh managed the distribution of many
hundreds of copies of drafts to reviewers. We received valuable
assistance and technical advice from Ben Adida, Ole Agesen, Ken
Arnold, Rick Cattell, Asmus Freytag, Norm Hardy, Steve Heller, David
Hough, Doug Kramer, Nancy Lee, Marianne Mueller, Akira Tanaka, Greg
Tarsy, David Ungar, Jim Waldo, Ann Wollrath, Geoff Wyant, and Derek
White. We thank Alan Baratz, David Bowen, Mike Clary, John Doerr, Jon
Kannegaard, Eric Schmidt, Bob Sproull, Bert Sutherland, and Scott
McNealy for leadership and encouragement.

The on-line Bartleby Library of Columbia University, at URL:

http://www.cc.columbia.edu/acis/bartleby/

was invaluable to us during the process of researching and verifying
many of the quotations that are scattered throughout this book. Here
is one example:

They lard their lean books with the fat of others' works.

-Robert Burton (1576-1640)

We are grateful to those who have toiled on Project Bartleby, for
saving us a great deal of effort and reawakening our appreciation for
the works of Walt Whitman.

We are thankful for the tools and services we had at our disposal in
writing this book: telephones, overnight delivery, desktop
workstations, laser printers, photocopiers, text formatting and page
layout software, fonts, electronic mail, the World Wide Web, and, of
course, the Internet. We live in three different states, scattered
across a continent, but collaboration with each other and with our
reviewers has seemed almost effortless. Kudos to the thousands of
people who have worked over the years to make these excellent tools
and services work quickly and reliably.

Mike Hendrickson, Katie Duffy, Simone Payment, and Rosa Aimée González
of Addison-Wesley were very helpful, encouraging, and patient during
the long process of bringing this book to print. We also thank the
copy editors.

Rosemary Simpson worked hard, on a very tight schedule, to create the
index. We got into the act at the last minute, however; blame us and
not her for any jokes you may find hidden therein.

Finally, we are grateful to our families and friends for their love
and support during this last, crazy, year.

In their book The C Programming Language, Brian Kernighan and Dennis
Ritchie said that they felt that the C language "wears well as one's
experience with it grows." If you like C, we think you will like the
Java programming language. We hope that it, too, wears well for you.

James Gosling
Cupertino, California

Bill Joy
Aspen, Colorado

Guy Steele
Chelmsford, Massachusetts

July, 1996