flutter - Flutter-不可为空的实例字段'questionAnswer','questionText'必须初始化
问题描述
我正在通过在线课程学习颤振。我正在上课。所以我们必须创建一个具有字符串和布尔属性的类。下面是这个类:
class Question {
String questionText;
bool questionAnswer;
Question({required String q, required bool a}) {
questionText = q;
questionAnswer = a;
}
}
错误显示如下:
Non-nullable instance field 'questionText' must be initialized.
Non-nullable instance field 'questionAnswer' must be initialized.
有人请帮忙
解决方案
根据新的空值安全规则,您不能在不指定其值或进行空值检查的情况下初始化任何数据类型的变量。尝试这个:
class Question {
String? questionText;
bool? questionAnswer;
Question({@required String q,@required bool a}) {
questionText = q;
questionAnswer = a;
}
}
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