ansaurus

Question

Answer 1

+2 A:

I am not sure what you mean with "the value is not getting". You should clarify that bit more.

At least, its sole purpose is to listen on a value change so that you can do some business stuff based on the change such as logging or preloading some stuff related to the new value. When the initial value equals to the submitted value, then this method won't be invoked.

Here's a code snippet to play around with it yourself:

<h:form>
    <p>Input value: <h:inputText value="#{bean.value}" valueChangeListener="#{bean.change}"/></p>
    <p>Old value: <h:outputText value="#{bean.oldValue}" /></p>
    <p>New value: <h:outputText value="#{bean.newValue}" /></p>
    <p><h:commandButton value="submit" action="#{bean.submit}" /></p>
</h:form>

Bean:

package com.example;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import javax.faces.event.ValueChangeEvent;

@ManagedBean
@ViewScoped
public class Bean {

    private String value;
    private String oldValue;
    private String newValue;

    public void submit() {
        System.out.println("Submit: " + value);
    }

    public void change(ValueChangeEvent event) {
        oldValue = (String) event.getOldValue();
        newValue = (String) event.getNewValue();
        System.out.println("Change: " + oldValue + " to " + newValue);
    }

    public String getValue() {
        return value;
    }

    public String getOldValue() {
        return oldValue;
    }

    public String getNewValue() {
        return newValue;
    }

    public void setValue(String value) {
        this.value = value;
    }

}

Update: as per your update: you're using two different instances of the bean. You're actually displaying the values of the managed bean, not of the bean which is newly created by f:valueChangeListener.

BalusC 2010-08-29 16:26:05

Hi BalusC, please read my edited post. I am not using valuelistener of component. I am using `f:valueListener`. Can you find bug in my code? I am reading this article :-http://java-server-faces.blogspot.com/2006/04/valuechangelisteners-what-you-need-to.htmlBut it is not working :(

Ankit Rathod 2010-08-29 16:32:19

See the update. To fix this problem, go ahead with my proposed approach.

BalusC 2010-08-29 16:52:17

Hi BalusC, I didn't quiet understand. So what do i have to do next?

Ankit Rathod 2010-08-29 16:53:52

The `f:valueChangeListener` creates a **new** instance of the bean. It is not using the same instance as the input/output components are displaying. You've now two beans and you're displaying values from the "wrong" bean. Use my approach to achieve the requirement you initially had in mind. Use your approach to completely detach listening on change events from the managed bean (and you're not interested in accessing the value change listener bean in the view).

BalusC 2010-08-29 16:57:28

Great! Thanks BalusC. Btw, your points have enormously grown! Last time when i used JSF 2.0 in June they were 54.4k. Now they are 82.8k. This way you will even break Jon Skeet's record.

Ankit Rathod 2010-08-29 17:00:57

ansaurus

tags:

views:

answers:

ValueChangeListener not working

related questions