CODE EXAMPLE FOR JAVA

primefaces custom validate

@FacesValidator("fooValidator")
public class FooValidator implements Validator {

    @Override
    public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
        // ...

        if (valueIsInvalid) {
            throw new ValidatorException(new FacesMessage("Value is invalid!"));
        }
    }

}