RichFaces Interview Questions and Answers
Ques 16. What is a4j:ajax?
a4j:ajax is one of our core behaviors, extending the base JSF 2.0 f:ajax tag. This tag triggers an Ajax request when the specified parent event is triggered.
<h:inputText value="#{userBean.name}"> <a4j:ajax event="keyup" render="out" /></h:inputText><h:outputText value="#{userBean.name}" id="out" />Ques 17. What is a4j:commandLink in RichFaces?
The a4j:commandLink combines the standard h:commandLink with our own a4j:ajax. This not only reduces typing, but also inherits all a4j:ajax special options.
Ques 18. What is a4j:actionListener in RichFaces?
Use a4j:actionListener to register an ActionListener class on a parent action component. Multiple listener methods can be registered on an action components in this way.
The a4j:actionListener tag differs from the standard JSF tag in that it allows the listener to be attached in any of three ways:
- By listener method, using the listener attribute.
- By listener class, using the type attribute.
- By object binding, using the binding attribute.
<h:commandButton value="Update"> <a4j:actionListener listener="#{bean.actionMethod}"/> <f:ajax render="messages"/></h:commandButton>Ques 19. What is a4j:jsFunction in RichFaces?
The a4j:jsFunction component creates a JavaScript function that allows you to send JSF Ajax requests from any JavaScript. You define the Ajax and JSF properties just like a4j:ajax, or a4j:commandButton, and a4j:jsFunction creates the JavaScript for you. The component sends a request using the standard JSF mechanisms. Note that this means a JSF form is required.
The following example shows how to use a4j:jsFunction to create a function named updateName. This is then called on mouseover of the different names. This triggers the full round trip Ajax request and renders the updated name.
<span onmouseover="updateAddress('WithoutBook')" onmouseout="updateAddress('')">WithoutBook</span>
<a4j:jsFunction name="updateAddress" render="showAddress"> <a4j:param name="address" assignTo="#{bean.address}" /></a4j:jsFunction>Ques 20. What is a4j:param in RichFaces?
<a4j:commandButton value="Update Name" render="rep"> <a4j:param value="WithoutBook" assignTo="#{bean.name}" /></a4j:commandButton>
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