toString method Null safety

  1. @override
String toString()

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 represetion.

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.


String toString() {
  switch (exception.runtimeType) {
    case InvalidArgumentException:
      return "${key}: argument should start with letter compose by letter, _ or digits";
    case InvalidChoiceException:
      return "${key}: choice only support select, plural, gender";
    case InvalidOptionException:
      final typedException = exception as InvalidOptionException;
      return "${key}: ${typedException.option} must be one of the ${typedException.validOptions}";
    case MissingCloseCurlyException:
      return "${key}: missing }";
    case MissingOpenCurlyException:
      return "${key}: missing {";
      return "";