测验代码无效

Question

enter code here我正在尝试顶级使代码可行，但它不起作用。有一个类，ListOfQuestions但数据没有输入列表。它的测验应该有几个问题以及四个选项，每个问题都可以回答。但问题不会进入ListOfQuestions。

感谢您的帮助。

 public class Main {

    public static void main(String[] args) {
    // write your code here
        ListOfQuestions quiz1 = new ListOfQuestions();
        Quiz quiz = new Quiz(quiz1);
        quiz.add();
        quiz.startQuiz();
    }
}

    import java.util.*;
import java.util.stream.Collectors;

public class Question {

    private String question;
    private Map<String, String> choices;
    private String correctAnswer;

    public Question(String question, String correctAnswer) {
        this.question = question;
        this.choices = new TreeMap<String, String>();
        this.correctAnswer = correctAnswer;
        //System.out.println(question);
    }

    public void addChoices(String option1, String option2, String option3, String option4) {
        this.choices.put("A", option1);
        this.choices.put("B", option2);
        this.choices.put("C", option3);
        this.choices.put("D", option4);
    }

    public String getCorrectAnswer() {
        return this.correctAnswer;
    }
    public String getQuestion() {
        return this.question;
    }

    public void enterChoice(String choice) {
        if (choice.toUpperCase().equals(correctAnswer)) {
            System.out.println("Bingo! your answer is correct");
        } else {
            System.out.println("Incorrect answer");
        }
    }

    @Override
    public String toString() {
        return this.question;
    }
    /*public void print() {
        Map<Letter, String> question = this.choices.entrySet().stream().sorted(Map.Entry.comparingByKey()).collect(Collectors.toMap(
                Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap :: new));

        question.forEach((k,v)->System.out.println(k + ": " + v));


    }*/
}
class Quiz{
    private ListOfQuestions quiz;
    public Quiz(ListOfQuestions quiz) {
        this.quiz = quiz;
     }

    public void add() throws ClassCastException{
        try {
            Question question1 = new Question("Question1", "C");
            question1.addChoices("Answer1", "answer2", "answer3", "answer4");
            this.quiz.addQuestion(question1);

            Question question2 = new Question("question2", "B");
            question2.addChoices("answer1", "answer2", "answer3",
                    "answer4");
            this.quiz.addQuestion(question2);
        } catch (Exception e) {
            System.out.println("error");
        }
    }

    public void startQuiz() {
       this.quiz.pickQuestion();
    }

}

import java.util.ArrayList;
import java.util.List;

public class ListOfQuestions {

    private List<Question> questions;

    public ListOfQuestions() {
        this.questions = new ArrayList<Question>();
    }

    public void addQuestion(Question question) {
        this.questions.add(question);
    }

    public void pickQuestion() {
        for (Question question : this.questions) {
            System.out.println(question);
        }
    }
}

Answer 1

问题在于Question.toString()方法。迭代Map.entrySet()时，它返回Map.Entry (combination of key and value)而不是条目中的键。

示例：

        for (Map.Entry<String, String> key : this.choices.entrySet()) {
            System.out.println(key.getKey() + " : " + key.getValue());
        }

Answer 2

这里我只更改了可行的代码

将测验变量添加到类测验，如下所示，

public class Quiz {
ListOfQuestions quiz;
public Quiz(ListOfQuestions quiz) {
    this.quiz = quiz;
 }

public void add() throws ClassCastException{
    try {
        Question question1 = new Question("Question1", "C");
        question1.addChoices("Answer1", "answer2", "answer3", "answer4");
        this.quiz.addQuestion(question1);

        Question question2 = new Question("question2", "B");
        question2.addChoices("answer1", "answer2", "answer3",
                "answer4");
        this.quiz.addQuestion(question2);
    } catch (Exception e) {
        System.out.println("error");
    }
}

public void startQuiz() {
   this.quiz.pickQuestion();
} 
} 

更改Question类中的toString方法，如下所示，

@Override
public String toString() {
    String sentence = "";
    for (Map.Entry<String, String> key : this.choices.entrySet()) {
        sentence += this.choices.get(key.getKey());
    }
    return this.question;
}

此代码更改仅适用于您的代码。

Answer 3

您的toString()方法包含suspicious call，只需修改即可返回：

return this.question + " " + this.getCorrectAnswer();