JSF NoSuchMethodException

Question

Hi!
I constantly receive a NoSuchMethodException in my simple JSF application. Found one similar post in the forum, but there were no solution to the problem there...
Basically I have a JSP with this code:
<h:commandLink id="reload" action="update" actionListener="#{mainBean.changeID}">
  <h:outputText id="history" value="#{history.endTask}"/>
</h:commandLink>And my backing bean:
import javax.faces.event.ActionEvent;
import javax.faces.event.ActionListener;
public class MainBackingBean implements ActionListener {
  public void changeID(ActionEvent actionEvent) {
    System.out.println("this time maybe?");
}faces-config.xml:
<managed-bean>
  <managed-bean-name>mainBean</managed-bean-name>
    <managed-bean-class>
      com.util.ejb.backing.MainBackingBean
    </managed-bean-class>
  <managed-bean-scope>session</managed-bean-scope>
</managed-bean>The stacktrace looks like this when clicking the link:
15:44:58,244 ERROR [[FacesServlet]] Servlet.service() for servlet FacesServlet threw exception
javax.faces.el.EvaluationException: Exception while invoking expression #{mainBean.changeID}
Caused by: java.lang.NoSuchMethodException: com.util.ejb.backing.MainBackingBean.changeID(javax.faces.event.ActionEvent)
I'm all out of ideas what can be causing this. I have tried to access the method from within the class which works fine, and the JSF seem to render fine otherwise. I am thankful for all suggestions!
Best regards,
Peter

Answer 1

Thanks for looking for a solution before posting. I'd be glad to help you out.
First off, you don't actually need to implement ActionListener on your bean when you access it this way. There's two ways to add an action listener to a component, the first is with the actionListener attribute (as you've done), the other is by using the f:actionListener tag.
When you use the actionListener attribute, you just have to have a method that is executed when an action happens (the method needs to have a specific signature though). You are very close to having the right method signature. Here's the signature your method should match (in fact, it's so close that I'm not sure this is necessary):
  public void changeID(ActionEvent actionEvent) throws AbortProcessingException {
    //perform actions
  }Anyways, the biggest thing here is to remove the implements ActionListener. This puts some method requirements onto your MainBackingBean that you have not fulfilled.
Doing the above ought to solve your NoSuchMethodException errors. The next bit is for informational purposes.
The second way to add an ActionListener to a component is with the f:actionListener tag. The f:actionListener tag is added as a child to your commandLink or commandButton. It would look something like this:
<h:commandLink id="reload" action="update" actionListener="#{mainBean.changeID}">
  <h:outputText id="history" value="#{history.endTask}"/>
  <f:actionListener type="your.package.name.ActionListenerClassName" />
</h:commandLink>This will register an action listener, of class your.package.name.ActionListenerClassName, on the commandLink.
When you create the ActionListenerClassName, this is when you need to implement ActionListener. By implementing ActionListener this forces you to write the processAction method. The ActionListenerClassName class will look like this:
public class MyActionListener implements ActionListener {
     /* (non-Javadoc)
      * @see javax.faces.event.ActionListener#processAction(javax.faces.event.ActionEvent)
     public void processAction(ActionEvent event)
          throws AbortProcessingException {
          //Perform action here
}And that's all there is to it.
Hope this helps!
CowKing