Android “No Class Deff. Find Error :xxxxxx"问题

There are only three reasons you will ever get this error:

The class genuinely doesn't exist. If you are using code from an official example and getting this, make sure you have the latest build of the library
You have not added the jar to your build path. To fix this, right click on the jar in Eclipse, and do Build Path ► Add to Build Path.
Your jar is not in the

/libs

folder. This happens when you have added the jar to the build path, but newer versions of ADT need it to be in

/libs

. Put it there and re-add it to the build path.
Mostly, such errors occur because newer versions of the ADT require all external jars to be in the

/libs

folder. Your colleague was probably on a different version than you, and hence the error.

简单来说：

把第三方包从libraries移除，然后把lib改成libs，

libs下面的jar包会自动的加到Android Dependencies里面。

修改之后android tools->fix project即可。