The hierarchy of type MainActivity is incompatible

Question

I created a new Android project via eclipse using MainActivity. I added an ActionBarSherlock to the project (Properties> Android and clicked Add). Then, when I replace "extends Activity" with "extends SherlockFragmentActivity", I get a compilation error "The hierarchy of type MainActivity is incompatible."

I also tried to create a project without an Activity, and then created a class "MainActivity" that inherits from SherlockFragmentActivity, and there are no compile-time errors, but with a runtime error "ClassNotfoundException: com.NadavLitvak.nadavfragmentdemo. MainActivity"

Answer 1

Your project should also have a link to android-support-v4.jar (which is included in the ABS libs folder.) So Properties-> Java Build Path-> Add JARs ... and select this jar from ActionBarSherlock-> libs

Answer 2

Sometimes, when Eclipse gets late, it does not add the SDK jar to your project (there is no project in the Android xy folder), so you need to add it. Properties> Android> Project Build Target (usually nothing is marked)