executable - make your Jar not to be decompiled

Question

How can I package my Java application into an executable jar that cannot be decompiled (for example , by Jadclipse)?

Answer 1

You can't. If the JRE can run it, an application can de-compile it.

The best you can hope for is to make it very hard to read (replace all symbols with combinations of 'l' and '1' and 'O' and '0', put in lots of useless code and so on). You'd be surprised how unreadable you can make code, even with a relatively dumb translation tool. This is called obfuscation and, while not perfect, it's sometimes adequate.

Remember, you can't stop the determined hacker any more than the determined burglar. What you're trying to do is make things very hard for the casual attacker. When presented with the symbols O001l1ll10O, O001llll10O, OO01l1ll10O, O0Ol11ll10O and O001l1ll1OO, and code that doesn't seem to do anything useful, most people will just give up.