Add the code below in jsp file.
<!--name attribute inside select tag must be a variable in action class with getter/setter -->
<!-- test variable sets the value of selected item in action class -->
<select name="test">
<!-- name attribute could be anything you want but value attribute must be a model class variable-->
<s:set name="lead_string_LS_ID" value="MasterDataModel.string_LS_ID" />
<!-- value attribute must be a list to iterate, status (an instanceof IteratorStatus will be pushed into stack upon each iteration)or result -->
<!-- var Name used to reference the value pushed into the Value Stack (my list contain leadSource_String_Id)-->
<s:iterator value="leadSource_list" status="result" var="leadSource_String_Id">
<!--#lead_string_LS_ID is value taken from <set> tag above. Note # must be in-front of the name
leadSource_String_Id is element specified in var of <iterator> tag
-->
<s:if test='(#lead_string_LS_ID.equals(leadSource_String_Id))'>
<option value="<s:property value='leadSource_String_Id'/>" selected="selected">
<s:property value="leadSource_String_Name" />
</option>
</s:if>
<s:else>
<option
value="<s:property value='leadSource_String_Id'/>">
<s:property value="leadSource_String_Name" />
</option>
</s:else>
</s:iterator>
</select>
