Missing required library in eclipse for non-required library

Question

I'm using Eclipse for Java Develepers (Juno x64 running on Windows 7).

I have a project in which I was trying out a jar I no longer need (args4j), so have removed the dependency. At some point, my PC lost power unexpectedly, and I've since restarted Eclipse.

My project now has an error, "Project 'MyProject' is missing required library: '/path/to/args4j-2.0.21.jar'". I was working with the project for some time after removing the dependency without any issues.

Under the Project Properties > Java Build Path, there's no reference to args4j in any of the tabs.

I've tried:

• searching for the string "args4j" in all files within my project, but there are no matches. There are a bunch of references within <workspace>\.metadata\.plugins\org.eclipse.core.resources\.history\, but I'm reticent to touch them out of fear I might break something else.
• [Edit] clean rebuild has no effect.

Does anyone have any idea why Eclipse is complaining, and what I might be able to do to fix it?

Answer 1

Please do the following, if one does not solve your problem, skip to the next one:

1. Check .classpath file in your project folder. You might have a reference there.
2. Close and re-open the project without closing eclipse, this might rebuild Eclipse resource cache.
3. Make a clean build after re-opening.
4. Re-import your project into a clean workspace.

Answer 2

Re-adding the problematic jar, then removing it did the trick. This is better than reconfiguring the entire workspace in my case, as I have many projects, and ADT configuration in my workspace.