When to use short and byte

when do i should really use byte and short anyway?
let's say i'm writing a MIDlet and i really really want to save up some memory at run time, would it be helpful if i will use short and byte if i dont need large numbers? let's say i only need a maximum representation of 500?
i know int is commonly used, but is it worth the change?

I don't know about the Micro Editon VM, but the Java Standard Edition run-time VM has no special instructions for operating using byte primitives as opposed to, say, integer or short primitives, and byte primitives in the VM are stored as ints, I believe. So, chances are your optimizations of these primitives aren't going to save you that much in terms of speed or memory. However, again, my previous comments only apply to the Standard Edition VM [feel free to correct them if I am wrong, as I am not sure if these restrictions have changed since Java v1.3 or not].
Plus, if your value is going to be a maximum of 500, you need a short because the signed byte primitive will only be valid across the -128 to 127 range.
-Dok

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From my point of view, simulator is suitable for the logical functionality testing of your application. In order to benchmark your application, you should use an emulator whose configuration is close to your real card.
I used to participated into a smart card benchmark project. The real performance depends on many factors, even the driver for the card reader can affect the application performance. I've never used a simulator to test an application performance so I haven't got any problem like yours. Just some ideas to share with you.
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JDL

When to use short and byte

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