Java Reference
In-Depth Information
Admittedly, this solution suffers from the same problem that it's trying to cure: there's
no set individual or organization that can actually dictate to vendors exactly which JSRs
they must support. Consequently, these attempts at unification are themselves not per-
fect; they rely on market forces for their success. However, the expert groups behind
these JSRs often include key manufacturers and operators—companies including Nokia,
Vodafone, Motorola, Orange, and Sun—lending credibility and momentum to these
efforts to stem platform fragmentation.
Reading a JSR
Since you've made it this far in the topic, I'll let you in on a little secret: a lot of what
I've told you throughout this topic is available in the JSRs that document the APIs
you've read about.
1
In fact, Java ME changes so quickly that in practice, it's better for
you to be familiar with the JSRs that define the platform than for you to have simply
read a book or two on Java ME. (Of course, there's no substitute for actual experience
writing code for the platform, too!) That way, as vendors introduce new APIs for
emerging technologies, you'll be prepared to learn about the APIs and how to use
them in your application.
Broadly speaking, most JSRs have the following contents (often with these titles):
•
Introduction
: States the purpose for the JSR. This introduction usually tells you
the business case for the JSR; in the case of an optional API, it will tell you why the
expert group that drafted the JSR felt the Java developer community needed the
optional API.
•
Contributors
: Lists the companies (and often people) behind the creation of
the JSR.
•
Glossary
: Defines domain-specific terms that the JSR uses, and often recaps
the definitions of
must
,
must not
,
should
,
should not
, and
may
, as described in
Request for Comments (RFC) 2119, “Key Words for Use in RFCs to Indicate
Requirement Levels.”
•
Packages
: Describes the packages the JSR introduces to the Java environment.
•
APIs
: Describes the classes and interfaces in the packages the JSR introduces.
•
Samples
: Shows how to use the APIs the JSR introduces. If you're lucky, the JSR
will contain samples.
1.
That said, I've tried to give you practical experience in applying the Java ME APIs, as well as make the
material a little less dry than Atacama Desert.
