If you have multiple display areas in your app you would have multiple 
ActivityMappers (one per display area, e.g. a master area and a detail 
area). Now if you go to a Place each ActivityMapper can return a different 
Activity based on the Place. So its more like one-to-<number of activity 
mappers>. A common example is that you have a ListEmailActivity that shows 
a list of emails and a EMailDetailsActivity that actually shows the 
selected email's content. Both can be started at the same time if the list 
of emails and the contents of the selected email are visible at the same 
time. If an ActivityMapper does not need to return an Activity for a place 
it can return null or return a default Activity that displays a message or 
something. You could use both methods, e.g. if you return null it means 
"hide the entire display area because I don't need it for that place" and 
if you want to show a message return a MessageActivity instead.

It can also happen that an ActivityMapper can start the same Activity for 
different places. For example you could have a single ListActivity that 
defines a general set of features for a list style view (for example 
searching the list, list ordering, etc.) but uses a ListAdapter to manage 
the displayed objects. If you now have EmailListPlace, PersonListPlace, 
etc. they all would start a ListActivity but for each Place the 
ListActivity would use a different ListAdapter, e.g. EmailAdapter, 
PersonAdapter, etc. 

-- J.

-- 
You received this message because you are subscribed to the Google Groups 
"Google Web Toolkit" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/google-web-toolkit/-/ahsrTNbpg8gJ.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to 
[email protected].
For more options, visit this group at 
http://groups.google.com/group/google-web-toolkit?hl=en.

Reply via email to