Build a JAR file that can only be executed?

Question

My project isn't complete, but I'd like to distribute some demo versions.

Is there a way to make a executable JAR file that won't give users access to its classes (e.g. when imported into Eclipse)?

If you say 'classes', do you mean the .class files or the .java files? If the last: then don't include them in the jar :) — Mark Rotteveel, Oct 28 '11 at 14:11

score 2 · Answer 1 · answered Oct 28 '11 at 04:04

Your only hopes lie through obfuscation or encryption. Neither is all that awesome in terms of protection against a determined poker-arounder. You sure it's worth it?

ProGuard is a free obfuscator (among other things). Encryptors use custom classloaders to decrypt encrypted byte code on loading.

score 2 · Accepted Answer · answered Oct 28 '11 at 04:11

No, a jar file is a zip file and there's no way to stop your users from looking inside it - because the JVM needs to look inside it to run it.

You can however:

Try converting it into a native executable (there are a few tools to do that)
Run an obfuscator over it (there's even more tools for that)

My experience with obfuscators are that they don't do a good enough job to acutally stop someone who's really keen. I've tried running decompilers over a variety of obfuscated classes and they're still easy enough to understand.

If you're interested in the native exe path, then this article might help.

Generally speaking, I don't think it's worth pursuing. If what you're distributing it valuable enough to the people you're giving it to, then they'll find a way to dig inside if they want to. Or if they're trustworthy then they won't. But technological solutions probably won't change that.

score 0 · Answer 3 · answered Oct 31 '11 at 06:16

0

Did you try Export>Java>Runnable JAR file option in Eclipse?

answered Oct 31 '11 at 06:16

Ayushman

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Build a JAR file that can only be executed?

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