A nice feature of Facelets is the ui:repeat tag, which iterates over a supplied list of values to do a full list on your page. One problem: it'll add an index to the generated id's, which can make using it with Ajax a bit of a drag. But if you're just using the f:ajax tag, that index is detected automatically, making ajaxifying the tag relatively easy. Here's a quick example: 

Say you want to make a page that offers three drop down menus with three choices each (it's a simple example, work with me here). Here's the data structure, set up as a bean:

   1 package demo;
   2 
   3 import java.util.ArrayList;
   4 import java.util.Arrays;
   5 import java.util.List;
   6 import javax.faces.bean.ManagedBean;
   7 
   8 @ManagedBean
   9 public class RepeatBean {
  10 
  11     private String[] sarray = {"one", "two", "three"};
  12     private String[] sarray2 = {"four", "five", "six"};
  13     private String[] sarray3 = {"seven", "eight", "nine"};
  14 
  15     private List<List<String>> llist;
  16 
  17     private String[] resultArray = {"two", "four", "nine"};
  18 
  19     public RepeatBean() {
  20         List<String> slist = Arrays.asList(sarray);
  21         List<String> slist2 = Arrays.asList(sarray2);
  22         List<String> slist3 = Arrays.asList(sarray3);
  23 
  24         llist = new ArrayList<List<String>>();
  25         llist.add(slist);
  26         llist.add(slist2);
  27         llist.add(slist3);
  28 
  29     }
  30     public List<List<String>> getLlist() {
  31         return llist;
  32     }
  33     public String[] getResultArray() {
  34         return resultArray;
  35     }
  36     public String getResultArray(int i) {
  37         return resultArray[i];
  38     }
  39     public void setResultArray(int i, String value) {
  40         resultArray[i] = value;
  41     }
  42     public void setResultArray(String[] resultArray) {
  43         this.resultArray = resultArray;
  44     }
  45 }

We create three lists - they'll be the content of the drop down menus. We then create a list of String lists - llist - we'll use this as the input for the . We also make a list to hold the results: resultArray. 

Now: to use it in a page:

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   2 <html xmlns="http://www.w3.org/1999/xhtml"
   3       xmlns:ui="http://java.sun.com/jsf/facelets"
   4       xmlns:h="http://java.sun.com/jsf/html"
   5       xmlns:f="http://java.sun.com/jsf/core"
   6       xmlns:c="http://java.sun.com/jsp/jstl/core">
   7     <h:head>
   8         <title>Repeat Test Demo</title>
   9     </h:head>
  10     <h:body>
  11 
  12         <h:form id="repeatForm">
  13             <ui:repeat value="#{repeatBean.llist}" var="list" varStatus="current" id="repeat">
  14                 <h:selectOneMenu value="#{repeatBean.resultArray[current.index]}" id="chooseOne">
  15                     <f:selectItems value="#{list}"/>
  16                     <f:ajax render="outText"/>
  17                 </h:selectOneMenu>
  18                 <h:outputText value="#{repeatBean.resultArray[current.index]}" id="outText"/>
  19                 <br/>
  20             </ui:repeat>
  21         </h:form>
  22     </h:body>
  23 </html>

This ends up generating ids for the outputText field that look like: repeatForm:repeat:2:outText. But because we're using the f:ajax tag, we only need to specify "outText" - the tag takes care of the work of finding out what the real id is. 

Neat, huh? In case you're not familiar with the ui:repeat tag - you should take a minute to get familiar with it, it's core Facelets functionality. By using the var value, we're saying that we want to create a list variable that will contain one of the lists in llist every iteration. By using varStatus and the index property, we're keeping track of all of the values selected.

Just a simple example of the use of the f:ajax tag in a complex rendered environment. As always, let me know if you have any questions.