My java program is packaged in a jar file and makes use of an external jar library, bouncy castle. My code compiles fine, but running the jar leads to the following error:>
If you are looking for a Fat JAR solution without unpacking or tampering with the original libraries but with a special JAR classloader, take a look at my project here.
Disclaimer: I did not write the code, just package it and publish it on Maven Central and describe in my read-me how to use it.
I personally use it for creating runnable uber JARs containing BouncyCastle dependencies. Maybe it is useful for you, too.