com.google.common.base.Preconditions

[IjonTichyRaumpilot]

When I debugged the example some classes could not be found.
I justed added the gexf4-core.jar to the build path etc.
I found the missing classes in:
http://code.google.com/p/guava-libraries/

Maybe it is because I didn't use Maven.

I see, here is how to setup a maven project in Eclipse
http://maven.apache.org/guides/mini/guide-ide-eclipse.html