Version 3

    The following simple example demonstrates how to update a price for a specific car from the list.

    Here is the code:


         <h:selectOneMenu id="select" value="#{carBean.currentItem}">
              <f:selectItems value="#{carBean.selectsList}"/>
         <h:inputText id="newprice" value="#{carBean.newPrice}" />
         <a4j:commandButton action="#{carBean.updateCarPrice}" reRender="price" value="Submit"/>
         <rich:dataList var="car" value="#{carBean.listOfCars}" id="list" 
              rows="6" type="disc" ajaxKeys="#{carBean.keyToUpdate}">
              <h:outputText value="#{car.make} #{car.model}"/><br/>
              <h:outputText value="Price: " styleClass="label" />
              <h:outputText id="price" value="#{car.price}" />


    There is no point in updating the whole component to change a price for a single

    car. Using the ajaxKeys attribute we can choose which item to update.


    The car model contains the next properties: a car title, model and price. :


     public class Car {
          private String make;
          private String model;
          private BigDecimal price = new BigDecimal(0);
          public Car() {}
          public Car(String make, String model, BigDecimal price) {
              this.make = make;
              this.model = model;
              this.price = price;
         /* --- getters and setters ----*/



    In the example you see a list of cars. To change a price for a car, choose in the select menu the car which you want to re-set the price for, type a new price in the input field and press the Sumbmit button to update the value.


    In the example, the <a4j:commandButton/> has the reRender attribute bound to the <h:outputText/> that outputs the price using the id attribute. While the ajaxKeys of  <rich:dataList/>  points to the list item to be updated.


    The bean used in the example looks like this:

    public class CarBean {
          private  List<Car> listOfCars;
          private BigDecimal newPrice;
          public List<SelectItem> selectsList = new ArrayList<SelectItem>();
          private Integer currentItem;
          private Set<Integer> keyToUpdate;
          public CarBean(){
               keyToUpdate = new HashSet<Integer>();
               listOfCars = new ArrayList<Car>();
               listOfCars.add( new Car("Chevrolet", "Corvette", new BigDecimal(18500)));
               listOfCars.add( new Car("Chevrolet", "Malibu", new BigDecimal(20500)));
               listOfCars.add( new Car("Chevrolet", "Tahoe", new BigDecimal(17890)));
               listOfCars.add( new Car("Ford", "Taurus", new BigDecimal(18580)));
               listOfCars.add( new Car("Ford", "Explorer", new BigDecimal(21540)));
               listOfCars.add( new Car("Nissan", "Maxima", new BigDecimal(15900)));
               SelectItem item;
               for(Car car : listOfCars){
                     item = new SelectItem(listOfCars.indexOf(car), car.getMake() + "
                   " + car.getModel());
    public void updateCarPrice(){
                keyToUpdate = Collections.singleton(currentItem);
          /* --- getters and setters ----*/




    In the example we use ajaxKeys to update  only one item. Actually, it’s possible to update multiple items: ajaxKeys contains an Object (java.util.Set) that holds keys of all items needed to be updated after an Ajax request.