Work in progress. Attempting to start an intent crashes with the message
  "Unable to find explicit activity class {com.example....EditItemActivity}; have you declared this activity in your AndroidManifest.xml?"

(The .... is to save typing a long name.) The class exists. The editor can see it and if a non-existent class is substituted, the editor notices.
The manifest file mentions the class in a way that appears normal for an activity. I don't know if some special notation is needed that
the class accepts intent messages.