Apply ValueChangeListener to programmatically created ADF Faces components

Again a post in series of  Working with ADF Faces Components programmatically
Previously i have posted about Getting value , Applying Action Listener , Applying Client/Server Listener, Creating and applying client Attributes, Setting value expression , Applying Validation to programmatically created component
Now this post post is about applying Value Change Listener to a component that is created at run time
See how to do this (Jdev 12.1.3)-

• First created a FusionWebApplication and a page in viewController project
• Dropped a button on page , on this button action i will create an inputText programmatically and assign Value Change Listener method reference to it
• To create new inputText i have added following code (described in previous post)




/**Method to add dynamically created component to a parent layout
     * @param parentUIComponent
     * @param childUIComponent
     */
    public void addComponent(UIComponent parentUIComponent, UIComponent childUIComponent) {
        parentUIComponent.getChildren().add(childUIComponent);
        AdfFacesContext.getCurrentInstance().addPartialTarget(parentUIComponent);
    }







        //Code to create af:inputText and add it to panelgroup layout
        RichInputText ui = new RichInputText();
        ui.setId("pit1");
        ui.setContentStyle("width:200px;color:navy");
        //getParentGroupLayoutBind is the component binding of parent panel group layout
        addComponent(getParentGroupLayoutBind(), ui);




• Next step is to create a Value Change Listener method in managed bean, that will be called on value change event of inputText




    /**ValueChangeListener method to be applied on programmatically created inputText
     * @param valueChangeEvent
     */
    public void testValuChangeListener(ValueChangeEvent valueChangeEvent) {
        FacesMessage msg = new FacesMessage("**VALUE CHANGE LISTENER CALLED** " + valueChangeEvent.getNewValue());
        FacesContext.getCurrentInstance().addMessage(null, msg);
    }




• Now assign this Value Change Listener method to programmatically created inputText, see how to do this
  Helper method to resolve Value Change Listener(javax.faces.event.ValueChangeListener)




//Packages used
   
import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.faces.application.Application;
import javax.el.MethodExpression;
import javax.faces.context.FacesContext;
import javax.faces.component.UIComponent;
import javax.faces.event.MethodExpressionValueChangeListener;




    /**Method to to resolve Value Change Listener method
     * @param actionName
     */
    private ValueChangeListener resolveValueChangeListener(String validatorName) {
        //ValueChangeListener method takes 1 argument of following type , we have to define that
        Class[] argtypes = new Class[1];
        argtypes[0] = ValueChangeEvent.class;
        FacesContext facesCtx = FacesContext.getCurrentInstance();
        Application app = facesCtx.getApplication();
        ExpressionFactory elFactory = app.getExpressionFactory();
        ELContext elContext = facesCtx.getELContext();
        MethodExpression methodExp = elFactory.createMethodExpression(elContext, validatorName, null, argtypes);
        return new MethodExpressionValueChangeListener(methodExp);
    }



To apply this Value Change Listener to inputText just write this - Pass exact el reference of bean value change listener method to resolveValueChangeListener method



//Pass string that contains proper el reference of Validator method 
ui.addValueChangeListener(resolveValueChangeListener("#{viewScope.Testbean.testValuChangeListener}"));




• All done :) Run and check application , On button click an inputText is created, i have entered a value  see Value Change Listener is called 

Cheers:) Happy Learning