Have you ever checked out a Java project and wondered what jars are required in the build path? How do you manage the classpath of you Eclipse projects? Do you still add jars manually? Do you use classpath variables? STOP! Use PDE projects!

Even if you don’t develop OSGi bundles. It’s so convenient to let PDE manage your classpath. Their classpath container driven by the manifest takes away all the pain. You can even ensure proper API usage across the layers/components by defining what packages are internal and what not.

See here for the necessary steps. Actually there are just two. Convert you Java project into a Plug-in project and edit the manifest.