x.y Activity is not a concrete class error message in manifest

Question

I got ... "is not a concrete class" error in manifest file.

The app works though. I can build and test without problem but this error bugs my eyes. Please help if you can.

When I ctrl + click on the activity name on the manifest it even opens the .java src file.

(The activity is actually called "MapInputActivty" - typo i know, but this is not the problem.)

Answer 1

That message is telling you that the MapInputActivty class is abstract, and instantiation will fail should the system try to launch it. The base classes for your app's components don't need to appear in the manifest. Only the concrete subclasses are necessary, so that the system has the appropriate information on the components' capabilities and functionalities. For example, though all of your Activities must be descendents of the Activity class, you wouldn't list the Activity class in the manifest.