Eclipse cannot create runnable jar - No resources selected

Question

When I try to export my project as a runnable jar Eclise gives me the following error:

No resources selected.

The project runs fine within Eclipse, I already

Answer 1

I fixed the problem, I exported the project as an archive file. Then I opened up a new workspace and imported the the archived project. After that I tried to export the project as a runnable jar, after two tries the jar runs as is it should.

I still don't know what the exact cause was but I hope someone how has run into the same problem finds this helpful.