I'm not sure to understand.
You mean if your jar depends on other stuff?
You mean if your jar depends on other stuff?
The way the bytecode is executed, the standard library, possible changes in GC and JIT implementation, other 3rd party libraries.
For example, if the jar code has a call to Thread.stop() and is loaded in Java 11 or later, when it comes to actually call that method you will get a java.lang.NoSuchMethodError exception.