as you know java class files are easily decompiled. how can i stop it ?

Hmm - you can't stop this as far as I know.
It's because they're not compiled at all - just precompiled... This precompiling is just some syntax check stuff - real compiling is done on the users machine.

haha.....you cant

these might give you some help or idea's

http://www.saffeine.com/

http://www.javaworld.com/javaworld/javatip...-javatip22.html

http://www.codework.com/dashO/product.html

SkyRaVeR is right, but to some point. It is possible to change the code in such a way, that it is almost impossible to decompile a program. To do this use special programs called obfuscators. They use several tricks:
- if you have a class called MyCollection, everyone knows what is the purpose of it, what about changing its name to "sZ_98gcd987"? Or better: to "for" (not possible in Java but possible in the precompiled code)?
- obfuscator adds some parts of the code which make it difficult to understand the meanin
- it also adds some parts of the unnecessary code which do not have impact on performance
I hope you've got the point. Try to search for obfuscators.

The same thing concerns C# and other .NET languages.

If you compress a executable with the upx.exe program, it seems to be undecompilable (hmm, strange word )

wicked put me on to upx to compress some programs i made in VB... and i did notice using a VB decompiler that it would not recognise the packed program

good point...cheers

sub0, upx don't work with java precompiled file. Only because java doesn't generate exe and fileExtension is .class

for java i personally think it aint possible....
as far as packing with upx...simply unpack it and decompile it

have you ever tried decompiling a famous programs classes like anfi ? they can't be decompiled and if they are decompiled not all of the code will be available.