Using negation in disabled attribute of h:selectBooleanCheckbox

jsf managed-bean
Karanveer Singh Sodhi picture Karanveer Singh Sodhi · Mar 27, 2012 · Viewed 17.4k times · Source

Could someone please tell me how to use negation in the value of a component say checkbox to enable and disable it?

I have to disable a checkbox when the value of a property (somevalue) in bean is false.

like in 

<h:selectBooleanCheckbox id="smthing" disabled="#{!somevalue}"></h:selectBooleanCheckbox>

For bean property

boolean somevalue;

should be diabled but it doesnt work. Maybe I am doing something wrong.

Also could someone please clarify if no value is assigned to the boolean what will be the case then.

Answer

BalusC picture BalusC · Mar 27, 2012

You need to reference it through the managed bean:

<h:selectBooleanCheckbox disabled="#{!bean.somevalue}" />

Another way, which is in my humble opinion prettier to read, for sure if the boolean property has a self-documenting name (somevalue isn't), is using the not keyword:

<h:selectBooleanCheckbox disabled="#{not bean.somevalue}" />

Also could someone please clarify if no value is assigned to the boolean what will be the case then.

The boolean is a primitive and just defaults to false when uninitialized as instance variable. If you have used a Boolean, it would have defaulted to null.

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