How can i perform conditional validations using JSR 303?

Say if a radio button is clicked and a field X is displayed based on the event.
If the event == true, validate the field in the bean
If the event == false, don't validate the field in the bean

I read that using spring validations, we can use applyIf annotation.
Does JSR 303 provide any annotation for this purpose?

That's hard to answer without knowing some more details. How are you triggering validation, are you invoking validation yourself via one of the methods on javax.validation.Validator? Possibly validation groups (see http://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#chapter-groups) may be useful for you.

--Gunnar