java - Reference directories correctly when launching a .jar from a batch file

You can ask the JVM about the location of a given class. If you know it is inside the jar you refer to, then you can then extract the location of the jar file, and then construct your file objects relative to that.

See http://stackoverflow.com/a/320595/53897 for details about

return new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath());