public function setFieldIdentifier($fieldIdentifier)
    {
        if ($fieldIdentifier == '' || Format::isIdentifier($fieldIdentifier)) {
            $this->fieldIdentifier = $fieldIdentifier;
        } else {
            $msg = "'${fieldIdentifier}' is not a valid QTI identifier.";
            throw new InvalidArgumentException($msg);
        }
    }
public function setFieldIdentifier($fieldIdentifier)
    {
        if ($fieldIdentifier == '' || Format::isIdentifier($fieldIdentifier)) {
            $this->fieldIdentifier = $fieldIdentifier;
        } else {
            $msg = "'${fieldIdentifier}' is not a valid QTI identifier.";
            throw new InvalidArgumentException($msg);
        }
    }
public function setFieldIdentifier ( $ fieldIdentifier ) { if ( $ fieldIdentifier == '' || Format :: isIdentifier ( $ fieldIdentifier ) ) { $ this -> fieldIdentifier = $ fieldIdentifier ; } else { $ msg = "'${fieldIdentifier}' is not a valid QTI identifier." ; throw new InvalidArgumentException ( $ msg ) ; } }
Set the field identifier. An empty string means it is not specified.

@param string $fieldIdentifier A QTI identifier.
@throws \InvalidArgumentException If $fieldIdentifier is not a valid QTI Identifier.
Set the field identifier . An empty string means it is not specified .