Using Proguard to obfuscate your classes in your midlets is a must. The jar size is reduced and the code is optimized.
But when I obfuscated my app an error is displayed and the jar is not obfustaced. The error is similar to:
WTF is this? :)
I don't know why, I didn't download the source of proguard (BTW this amazing tool is opensource)
How to fix it? Two options:
* disable optimization. It's not the best option but it helps. Use parameter -dontoptimize
* disable optimization partially. I used this option. The last proguard has many parameters for optimization, and I found the parameter that worked in my midlet:
this means the optimizer will avoid marking methods as static.
It worked for me, I hope it works for you.
Proguard optimizations site: http://proguard.sourceforge.net/manual/optimizations.html