Java Reference
In-Depth Information
•
CLDC 1.1 doesn't support thread groups or daemon threads
: The CLDC does sup-
port multithreading, but if you need to manage a group of threads, you must use
individual thread operations on members of a collection.
•
Class file verification is a two-step process in CLDC 1.1
: As I discuss in the “Building
CLDC/MIDP Applications” section in Chapter 3, the CLDC requires a preverifica-
tion step during application development and a subsequent completion of
verification after downloading.
•
For security reasons, CLDC 1.1 doesn't support user-defined class loaders
: The CLDC
must have an internal class loader that other code cannot override, replace, or
reconfigure in any way.
With the possible exception of CLDC 1.1 lacking class finalization and thread groups,
these differences are unlikely to affect your approach to application development. Larger
in scope, however, is the reduction of the CLDC class library itself, which I explore later in
the chapter (in the section “Changing the Java Class Library to Fit the CLDC”).
MOORE'S LAW AND MOBILE DEVICES
Moore's law—the observation that the number of transistors that can be fit on the die of an integrated
circuit is increasing exponentially—has driven many facets of the computing revolution, including the
increases in computing speed and memory density for more than 50 years. Documented by Gordon
Moore in an article in
Electronics Magazine
in 1965, the law isn't one of nature, but rather a recognition
of the economies of scale provided by integrated circuit production.
For mobile devices, Moore's law brings two key points: the ever-dropping cost of each transistor
means that more computing power can be purchased for less money, and that the increased transistor
density brings faster devices with more memory in portable form factors at the same exponential pace
as it brings to desktop users. That is not to say, however, that the capabilities of mobile and desktop
devices will
converge
, as Moore's law is in play for larger computing platforms as well.
Moreover, one area remaining largely untouched by Moore's law is in providing energy for mobile
devices. While the battery industry has seen many improvements in technology over the last two
decades, these advancements have not been exponential in nature, leading to aggressive work on the
part of hardware and software developers to manage power consumption at the hardware and soft-
ware levels. This has a direct impact on computational resources, of course, which consume power
while operating.
These factors are likely to persist into the future, meaning that while mobile devices continue to
get increasingly powerful, it's unlikely that mobile devices and desktops will ever truly converge.
Instead, it's likely that mobile devices will become sufficient to support the majority of operations per-
formed by yesterday's desktops—something I talk more about in the “Looking Toward the Future of the
CLDC” section later in this chapter.
