// Creates a custom validator.
Validator statuteValidator = createStatuteValidator(crimeCode);
// Can add the same validator to multiple subjects to do multi-field
// validation.
crimeValidation.addValidator(statuteValidator);
ValidatorController.addAsFocusListener(dateOfCrime, statuteValidator);
// Cannot book someone for a crime more than 30 years old.
ValidatorController.addAsFocusListener(dateOfCrime, new DateRangeValidator(
offsetDate(30), new Date()));