Java中的toString

Question

在这里，我试图为Question和ChoiceQuestion类提供一些toString方法。应该打印问题文本（针对两个类），并打印带有ChoiceQuestion选项的选项号。知道我在ChoiceQuestion类中缺少什么来完成这项工作吗？任何帮助，将不胜感激！

What was the original name of the Java language?
1: *7
2: Duke
3: Oak
4: Gosling

/**
 A question with multiple choices.
 */
class ChoiceQuestion extends Question
{
  private ArrayList<String> choices;

  /**
   Constructs a choice question with no choices.
   */
  public ChoiceQuestion()
  {
    choices = new ArrayList<String>();
  }

  /**
   Adds an answer choice to this question.
   @param choice the choice to add
   @param correct true if this is the correct choice, false otherwise
   */
  public void addChoice(String choice, boolean correct)
  {
    choices.add(choice);
    if (correct)
    {
      // Convert choices.size() to string
      String choiceString = "" + choices.size();
      setAnswer(choiceString);
    }
  }

  public String toString()
    {
        return choices.toString() + super.toString() ;
    }




}

class Main {
  public static void main(String[] args) {
    Question question = new Question();
    question.setText("Who was the inventor of Java?");
    question.setAnswer("James Gosling");
    boolean resultQuestion = question.checkAnswer("Andrew Gosling");
    String toStringOutputQuestion = question.toString();

    ChoiceQuestion choiceQuestion = new ChoiceQuestion();
    choiceQuestion.setText("What was the original name of the Java language?");
    choiceQuestion.addChoice("*7", false);
    choiceQuestion.addChoice("Duke", false);
    choiceQuestion.addChoice("Oak", true);
    choiceQuestion.addChoice("Gosling", false);
    boolean resultChoiceQuestion = choiceQuestion.checkAnswer("3");
    String toStringOutputChoiceQuestion = choiceQuestion.toString();
  }
}

/**
 A question with a text and an answer.
 */
class Question
{
  private String text;
  private String answer;

  /**
   Constructs a question with empty question and answer.
   */
  public Question()
  {
    text = "";
    answer = "";
  }

  /**
   Sets the question text.
   @param questionText the text of this question
   */
  public void setText(String questionText)
  {
    text = questionText;
  }

  /**
   Sets the answer for this question.
   @param correctResponse the answer
   */
  public void setAnswer(String correctResponse)
  {
    answer = correctResponse;
  }

  /**
   Checks a given response for correctness.
   @param response the response to check
   @return true if the response was correct, false otherwise
   */
  public boolean checkAnswer(String response)
  {
    return response.equals(answer);
  }

    public String toString()
    {
        return text + answer;
    }

}

Answer 1

嗯，准确地定义您遇到的问题很有帮助。

这里是我发现的东西的快速浏览...

1）您需要在Arraylist的顶部使用import语句：“ import java.util.ArrayList;”

2）您至少需要一个公共课：“公共课Main {”

3）您的程序未在屏幕上输出任何内容。添加一些System.out.println行。