dart – Flutter：lib1 :: Object类型的值不能分配给lib2 :: Obj

import 'package:flutter/material.dart';
import 'package:startup_namer/misc/Constants.dart';
import 'package:startup_namer/ui/question_text.dart';
import '../utils/question.dart';
import '../utils/quiz.dart';
import '../ui/answer_button.dart';
import '../ui/correct_wrong_overlay.dart';

class QuizPage extends StatefulWidget {
    @override
    State createState() => new QuizPageState();
}

//States are mutable
class QuizPageState extends State<QuizPage> {

    static List<Question> quizQuestions = [
        new Question("5 * 5 = 25",true),new Question("4 + 2 = 6",new Question("4 + 2 = 7",false),new Question("Computers don't use energy",new Question("B is after A in the alphabet",];

    Question currentQuestion;
    Quiz quiz = new Quiz(quizQuestions);

    String questionText;
    int questionNumber;
    bool isCorrect,overlayShouldBeVisible = false;


    @override
    void initState() {
        super.initState();
        this.currentQuestion = this.quiz.nextQuestion;
        this.questionText = this.currentQuestion.aQuestion;
        this.questionNumber = this.quiz.questionNumber;
    }

    @override
    Widget build(BuildContext context) {
        return new Stack( 
            fit: StackFit.expand,children: <Widget>[
                //Container for tons of stuff (Main page essentially)
                new Column(
                    children: <Widget>[
                        new AnswerButton(true,() => testMe(true)),new QuestionText(this.questionText,this.questionNumber),new AnswerButton(false,() => testMe(false)),],//<Widget>[]
                ),//Column
                (this.overlayShouldBeVisible) ? new CorrectWrongOverlay(true) : new Container()
            ] //<Widget>[]
        ); //Stack
    }
}

void testMe(bool isTrue){
    if(isTrue){
        print("it is true,huzzah!");
    } else {
        print("it is false,:(");
    }
}

我收到此错误：

Error: A value of type 'dart.core::List<#lib1::Question>' can't be assigned to a variable of type 'dart.core::List<#lib2::Question>'.

我正在关注this教程系列,并检查了他们的存储库的代码,但我无法看到导致此问题的原因.

如果没有其他模糊的问题类与之冲突,为什么我会看到这个投射错误？