NoClassDefFoundError for code in an Java library on Android

Question

I am experiencing an error quite often among my users. The app crashes during startup. When the MainActivity is supposed to be loaded the VM apparently cannot find the class

Answer 1

I have just figured out something with this error.

Just make sure that the library jar file contains the compiled R class under android.support.v7.appcompat package and copy all the res in the v7 appcompat support "project" in your ANDROID_SDK_HOME/extras/android/support/v7/appcompat folder.

I use Netbeans with the Android plugin and this solved my issue.