Classpaths, more

An email from a student. This will be discussed in class (12/11/01)

I am getting errors that say that the Oracle driver class cannot be found - however, the classes12.zip was packed in the jar file that I was running from. So I did some more testing...

I had been running the application by typing "java -jar javadb.jar"
I tried not using the -jar parameter, "java -cp javadb.jar javadb/JavaDB" and that failed also.
Then I realized that my profile already had the classes12.zip file in my CLASSPATH, so even if I didn't have the file in my jar, it should have been found. So I tried explicitly adding my classpath, "java -cp $CLASSPATH -jar javadb.jar". Didn't work.
So again I figured maybe it was the -jar parameter. So I tried it without, "java -cp $CLASSPATH:javadb.jar javadb/JavaDB". SUCCESS!!!

So I have changed my README file to require the user first extract the classes12.zip file from the jar they download and then run "java -cp classes12.zip:javadb.jar javadb/JavaDB". That seems to work, but my question to you is: do you know why this is so complicated? I don't understand why I couldn't just run it fine when the classes12.zip was packed in my jar. Also, does the -cp parameter override what you already had in your CLASSPATH variable? It seems to since I had to explicitly include it. You might want to forward this information on to the rest of the class because I know a lot of students were still having trouble with the ClassNotFound exception - maybe this is why.

See http://java.sun.com/j2se/1.3/docs/tooldocs/tools.html then basic tools

The standard options for java and Setting the classpath