JExcelAPI: java.lang.NoClassDefFoundError: jxl/Workbook

[DC200]

Cross post from new-java/26805-installing-java-libraries.html. I didn't know which other sub-forum to put this in.

I'm getting the following error during runtime while attempting to use the JExcelAPI:

Exception in thread "main" java.lang.NoClassDefFoundError: jxl/Workbook
	at demo.main(demo.java:10)
Caused by: java.lang.ClassNotFoundException: jxl.Workbook
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:319)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:264)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:332)
	... 1 more

The jar has been put into jre/lib/ext and the test code compiles fine with import jxl.*, but still no luck. It can see the package, but why can't it find the class definition?

This is the code I'm trying to test: Workbook workbook = Workbook.getWorkbook(new File("excel.xls"))

[DC200]

I seem to have found a temporary solution to this problem. After trying unsuccessfully to modify the classpath, I unpacked the jar and moved the folder "jxl" into the same directory as the class files I was trying to run. No runtime errors at all.