JSF checkbox listener

Question

<h:selectBooleanCheckbox id="deactivate" title="select to deactivate" />

I have a checkbox and a button on my JSF page. I want the button to be enabled only if checkbox is checked.

What is the JSF way of doing this with no manual javascript and no listener method on my java class. There should be way of doing it maybe with an expression something like;

"panel group rendered=#{}" 

one button rendered for enabled and one button rendered or disabled.

Answer 1

You need to this by calling a valueChangeListener on ajax call so you can enable/disable button
Here is checkboxes and button

       <h:selectBooleanCheckbox id="deactivate" title="select to deactivate" 
valueChangeListener="#{bean.myChangeListener}" onchange="submit()">

        <h:selectManyCheckbox value="#{user.favNumber1}">
            <f:selectItem itemValue="1" itemLabel="Number1 - 1" />
            <f:selectItem itemValue="2" itemLabel="Number1 - 2" />
            <f:selectItem itemValue="3" itemLabel="Number1 - 3" />
            <f:ajax event="change" execute="@this" render="dummyButton"/>
        </h:selectManyCheckbox>
    <h:commandButton id="dummyButton" value="OK" render="#{renderBean.myButton}">

You need create a render class with just one attribute whose value will be set in listener method i-e bean#myChangeListener

public class RenderBean{

    boolean myButton;
    public RendeBean(){

            myButton = true;

    }

    public void enableButton(){

          myButton = true;
    }

    public void disableButton(){

          myButton = false;
    }
}

And here is your bean#myChangeListener

public void myChangeListener(ValueChangeEvent e){
     RenderBean rb = (RenderBean) FacesContext.getCurrentInstance()
            .getExternalContext().getSessionMap().get("renderBean");
        if(e.getNewValue().toString().equals("1"))
                     rb.enableButton();
        else
                     rb.disableButton();
}

Answer 2

What is the JSF way of doing this with no javascript and no listener method on my java class

This is plain impossible. I gather that you actually meant, "no manually written JavaScript" (and thus you accept JSF-generated JavaScript as used by <f:ajax>) and "no manually written listener method" (and thus you accept JSF own magic on the component tree state).

In that case, this should do:

<h:form>
    <h:selectBooleanCheckbox binding="#{checkbox}">
        <f:ajax render="button" />
    </h:selectBooleanCheckbox>
    <h:commandButton id="button" value="submit" 
        action="#{bean.submit}" 
        disabled="#{not checkbox.value}" />
</h:form>

That's all. No additional JS code nor JSF bean properties or listener methods needed. Just a submit() action method.

The binding attribute will in this example put the UIComponent reference of <h:selectBooleanCheckbox> in the Facelet scope under the variable name checkbox. The EL expression #{checkbox.value} returns the value attribute of the component which represents in case of an UISelectBoolean component already a boolean, ready for use in command component's disabled attribute.

Note: if you're facing an incorrect EL error at the line disabled="#{not checkbox.value}" in an older Eclipse version, then you'd need to configure it as follows: Window > Preferences > Web > JavaServer Faces Tools > Validation > Type Coercion Problems > Unary operation boolean coercion problems set it to Warning or Ignore instead of Error. This is not necessary anymore since Eclipse Mars.

See also:

• How does the 'binding' attribute work in JSF? When and how should it be used?