在这个省道类中可以添加或删除什么？

Question

请问这个飞镖类的错误可能是什么？

class Question {

  String questionText;
  bool questionAnswer;

  Question({String q, bool a}) {
    questionText = q;
    questionAnswer = a;
  }
}

错误日志：

error: Non-nullable instance field 'questionText' must be initialized. (not_initialized_non_nullable_instance_field at [practice] lib\question.dart:5)
error: Non-nullable instance field 'questionAnswer' must be initialized. (not_initialized_non_nullable_instance_field at [practice] lib\question.dart:5)

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Answer 1

class Question {
  String QuestionText;
  bool QuestionAnswer;

  Question(this.QuestionText, this.QuestionAnswer);
}

或

class Question {
  late String QuestionText;
  late bool QuestionAnswer;

  // Question(this.QuestionText, this.QuestionAnswer);
  Question(String q, bool s) {
    QuestionAnswer = s;
    QuestionText = q;
  }
}

Answer 2

通过将添加到类型中，使您的字段为空。

class Question {

  String? questionText;
  bool? questionAnswer;

  Question({String q, bool a}) {
    questionText = q;
    questionAnswer = a;
  }
}