class Animal {
static final int DOG=-1, CAT=1, MOUSE = 0;
String saySomething(int kind) {
if (kind 0) return “meow”;
return “squeak”;
}
}

this also allows you to do DOG | CAT is != 0
CAT | MOUSE >= 0 etc

If you have a lot of cases then by grouping related ones into negative / positive you can use 0. The Java compiler is like the old C compilers back in the ’80s before any of the optimizations that were made (some C++ compilers can generate code that is almost as good as assembly, but since Java is already slow on Mobiles and size limited it is worth optimizing the code rather than letting the compiler, although a tool such as proguard means you can use more maintainable code, but it won’t solve all your problems since it doesn’t refactor the logic, just the generated code).

I’m writing a 3d game using mascot capsule, and even now in 2008 the hit from newing and method calls is enormous. As a result I performed many of the optimizations similar to the ones Mihai talks about and it’s over doubled the game’s speed.

On some of the many smaller handsets that we still have to support (our build list covers over 500 different j2me devices) then most of this post makes absolute sense.

Our apps have to run on very very slow, 64kj devices with less than 200k heap. You’re fighting for every byte on these devices, you better understand these concepts. And we’ll be supporting these devices for at least another 12 months.

Sorry, but give me proguard instead now!

Premature optimization is still the root of all evil…

–
Cedric