FriendlyMessage friendlyMessage = snapshot.getValue(FriendlyMessage.class); get error

[yopetra]

This string get error when trying to conver result of snapshot which is String to FriendlyMessage object.
Here is an error:
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.android.firebaseapp01.FriendlyMessage