toString method

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 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.


String toString() {
  String? name =;
  String nameString = (name == null) ? "" : " ($name)";
  Object? message = this.message;
  var messageString = (message == null) ? "" : ": ${message}";
  String prefix = "$_errorName$nameString$messageString";
  if (!_hasValue) return prefix;
  // If we know the invalid value, we can try to describe the problem.
  String explanation = _errorExplanation;
  String errorValue = Error.safeToString(invalidValue);
  return "$prefix$explanation: $errorValue";