}
protected Collection <Validator> validators() {
Collection <Validator> validators = new ArrayList <Validator> ();
validators.add(new EmptyValidator(classRoomNameText, screenMessageLabel, Validator.ERROR_REQUIRED_CLASSROOM_NAME));
validators.add(new EmptyMapValidator(computerItem.getTableContents(), screenMessageLabel, Validator.ERROR_REQUIRED_CLASSROOM_COMPUTER));
return validators;
}