toString method
A string representation of this object.
Some classes have a default textual representation,
often paired with a static parse
function (like int.parse).
These classes will provide the textual representation as
their string representation.
Other classes have no meaningful textual representation
that a program will care about.
Such classes will typically override toString
to provide
useful information when inspecting the object,
mainly for debugging or logging.
Implementation
@override
String toString() {
var string = '';
string += _cardNumber.isEmpty ? "" : 'Card Number = $cardNumber\n';
string += _expiryDate.isEmpty ? "" : 'Expiry Date = $expiryDate\n';
string += _cardIssuer.isEmpty ? "" : 'Card Issuer = $cardIssuer\n';
string += _cardHolderName.isEmpty ? "" : 'Card Holder Name = $cardHolderName\n';
return string;
}