confusion about s:select with multiple true

[Bhaarat Sharma]

I have been playing around with this sample code:

<s:select label="Months"
       name="months"
       headerKey="-1" headerValue="Select Month"
       list="#{'01':'Jan', '02':'Feb'}"
       value="#{'01','02'}"
multiple="true"
required="true"/>


This works as I want it to.  My question is, if I want values for 'list' and
'value' coming from the action class then should the method for list be
returning a hashMap? and value be returning a list? is that the only way?