When using ProGuard, you should be aware of a few technical issues, all of
which are easily avoided or resolved:
For best results, ProGuard's optimization algorithms assume that the
processed code never intentionally throws NullPointerExceptions or
ArrayIndexOutOfBoundsExceptions, or even OutOfMemoryErrors or
StackOverflowErrors, in order to achieve something useful. For instance,
it may remove a method call myObject.myMethod() if that call
wouldn't have any effect. It ignores the possibility that
myObject might be null, causing a NullPointerException. In
some way this is a good thing: optimized code may throw fewer exceptions.
Should this entire assumption be false, you'll have to switch off
optimization using the -dontoptimize option.
ProGuard's optimization algorithms currently also assume that the
processed code never creates busy-waiting loops without at least
testing on a volatile field. Again, it may remove such loops. Should this
assumption be false, you'll have to switch off optimization using
the -dontoptimize option.
When obfuscating, ProGuard writes out class files named
"a.class", "b.class", etc. If a package contains
a large number of classes, ProGuard may also write out
"aux.class". Inconveniently, Windows refuses to create
files with this reserved name (among a few other names). It's generally
better to write the output to a jar, in order to avoid such problems.