I\'ve downloaded the code for an Eclipse plugin. The code uses log4j, but it doesn\'t just use it as a library (referred jar), but as a \"bundle\". So it doesn\'t compile be
I assume you are using the Eclipse Plugin Development Environment (PDE). In this case, the log4j bundle needs to be imported into the "Target Platform".
The Target Platform is like a repository of bundles (i.e. plug-ins) that replaces the "classpath" in traditional Java development. You can find the location of the target platform and modify it by going to Preferences -> Plug-in Development -> Target Platform.
HOWEVER before doing this I strongly recommend you take some time to learn a bit about what you are working on! If you want to develop an Eclipse Plug-in you should at least learn what a plug-in is, and how its dependencies work. If you read a bit about the subject you should not have to ask such an extremely basic question on Stack Overflow... it is covered in all the introductory tutorials and FAQs.