All you should have to do here is go into the properties window for the project in the classpath - put the yoko-core and yoko-spec infront of the jdk and they will find the classes.
It did not help. I was still getting the exception. The only way to add a library to bootclasspath in Eclipse is AFAIK to create an User Library in Preferences and check the Boot library checkbox. Then I need to move this libraries to the top in Order/Export tab in the project preferences. Now it works. -- Lukas Zapletal http://lukas.zapletalovi.com