Appendix A. Superseded Threading Utilities
Readers of previous editions of this book will have noticed that many
of the classes we developed for those editions have been replaced.
The reason has to do with the many new classes provided by J2SE 5.0.
Prior to J2SE 5.0, developers were left to create or purchase a
library that provided the high-level threading support needed by more
complex programs. While these libraries can still be used, it is
recommended that programs migrate to the core J2SE 5.0 classes since
that leaves one less library to maintain, test, and download during
execution.
While the examples in the previous edition of this book are now
obsolete, there are a few advantages to including them in this
appendix (and in the online source). The examples were designed to
teach the subject of threading. They were designed to be simplistic,
not loaded with features, and specifically target a particular
subject. Most of those subjects are now discussed in relation to the
new classes in J2SE 5.0, and the rest of them are no longer necessary
since we are no longer maintaining our own library. Still, for
research purposes, there is advantage in examining them.
As this book goes to press, J2SE 5.0 is only a beta release, so many
developers cannot yet use the new classes in J2SE 5.0. Those
developers will also find these classes useful.
So for those who may be interested, here is a quick review of our
obsolete classes. Obviously, learning the examples in this appendix
is optional. Using these tools should be considered only if you must
use a virtual machine earlier than J2SE 5.0.
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