Okay, I think I'm on the verge of some kind of Eureka moment. Every once in a while, I find myself totally befuddled by paths and directory structures and how they are being used within programs such as Jenny and, well, let's face it, WinZip. I'm perusing jr.jar from inside of WinZip, hoping to find something that will help me figure out what I need to do to get Jenny working, and I'm looking at the path column. The jenny files are all located at this address: com\javaranch\db\ But I don't find this directory tree anywhere in my development directory. In fact, it doesn't exist anywhere that I can see. Is this directory structure located only inside of the jr.jar file? If I unzipped jr.jar, would it set up a directory named jr that would have all the inner directory trees mentioned in the path column, and the individual files located within their own trees? I'm missing some giant piece of the puzzle that is keeping me from seeing the whole picture here, I think.
My impression was (and I've never actually used it, just read about it) that Jenny generates Java classes, based on an existing database schema. So I think you need to add add jr.jar to your classpath, and then you should be able to run Jenny. You also need to create a properties file to tell it what to do, but that's covered in the documentation.
So, in short: don't open jr.jar, add it to your classpath.
You are right on the spot with respect to the jr.jar being a zipped up package of directories, and if you unzipped it, it would make the paths you describe.
So as long as you have the jr.jar file in your CLASSPATH, your programs should be able to use anything that is inside it. On my own computer, the .jar files have to be specified specifically (gee - so articulate today), whereas if you have .class files, it is enough to specify the directory within which they reside. So for .class files:
and for jr.jar:
Or something to that effect.
I can't promise that what I just told you is technically true - it just coincides with the way I make sense of it