Android java.lang.NoClassDefFoundError
Did you recently updated your eclipse android plugin (adt r17)? Then the following link might help:
How to fix the classdefnotfounderror with adt-17
Update: One year has passed since the question arose. I will keep the link, because even in 2013 it seem to help some people to solve the problem. But please take care what you are doing, see Erics comment below. Current ADT-Version is 22, I recommend using the most current version.
Edit the build path in this order, this worked for me.
Make sure the /gen is before /src
I fixed the issue by just adding private libraries of the main project to export here:
Project Properties->Java Build Path->Order And ExportAnd make sure Android Private Libraries are checked.
Screenshot:
Make sure google-play-services_lib.jar and google-play-services.jar are checked. Clean the project and re-run and the classNotfound exception goes away.