Problem with sorting using display tag

[swathi vellanki]

I want the userid to be sorted. So I wrote the code like this , but I defined my userid as string in my object.So it is sorting like string.
but want it to be sorted like number.How can I handle that . could any one please help me. Here is my code.


<s:set name="users" value="offices" scope="request"/>
<display:table name=" users " requestURI="" pagesize="${row}" sort="list" id="jobResults" class="candSearchResults" >
<display:column><s:checkbox name="checked"
fieldValue='%{ user. userId}'/></display:column>
<display:column property="user.userId" title="ID" sort="true"/>
<display:column property="user.userName" href="testing.action" paramId="userStatus" paramProperty="user.userId" title="Name" sort="true"/>
</display:table>