Re: return a Collection (Set or List)

thufir wrote:
> The scanFile method returns a List.  Sometimes, however, I want it to 
> return a Set.  When I change the return type to Collection I get an
error:
> 
> a00720398/data/BedAndBreakfast.java:33: incompatible types
> found   : java.util.Collection<a00720398.data.Guest>
> required: java.util.List<a00720398.data.Guest>
>         guests = console.scanFile(new File("Guests.txt"), new
GuestFactory
> ());
>                                  ^
> 1 error
> 
> 
> I've seen Collection used as a parameter in a signature, can it also be 
> used as a return type?  A quick Google seems to show "yes".  

You really should show the part of the code that actually has the problem.
 Read
  http://sscce.org/
to find out how.

The problem is not the return of the Collection but its assignment to a 
narrower type.  You can assign a List<Foo> to a Collection<Foo> but not
the 
other way around.

If that's not what happened, but I'll bet it is, then you should have
shown 
the declaration of 'guests'.  Or, for that matter, 'console' and
'scanFile()'.

-- 
Lew