how to protect .jar file from decompielation?

i know that i need obsfucator but it hass erros, if anyone can help i will be glad.

 

if you encrypt source as far as i know

if you encrypt you can also decrypt but obfusicator allows you to not open in decompilation, you need to hack it with hexid to ediit :)  and encrypt decrypt is really easy

As you said, using obfuscator such as http://proguard.sourceforge.net/.

 

And with obfuscation you still can open, but all variables and methods are renamed, which is almost impossible for random guys to understand it.

i have it but unfortnunetlly get to many errors, it isn't obsfucateing i think :( do you have any guide?

i used guides from youtube but not works :(

I tried it for like an hour without checking notice, I had 4 errors in final but .jar was still broken.

 

Well here is a how to for the GUI :

- compile your project

- in ProGuard, put input/output jars (input is the jar you want to obfuscate and the list of required jar that jar is using in order to normally compile... It includes some JAVA common jars too ! Output is the resulting jar, so rename it comparing to l2jserver.jar

- you press the button and voilà. You can also generate a table with all links before/after.

 

Personally I compiled it all good, except 4 errors (all about templates)