integer (not mandatory) field validation

[Maverick Schueler]

Spring MVC 3

I have a form with an integer form bean field (e.g. phoneNumber). This field is not mandatory. but I need to have it only digits (e.g. 0111234567890)
But whenever I keep the field blank, Spring treats it as String and throws exception.

Is there any way we can achieve this?

[James Boswell]

How about annotating your phone number field as follows:

@Pattern(regexp="[0-9]{1,8}", message="Please enter a valid phone number")
private String phoneNumber;

Obviously you can replace the max length 8 to suit your needs.