StAX和arraylist java

Question

我试图用StAX读取一个xml文档，但是我有一个小问题，我不知道如何修复它，我尝试在互联网上查找(也许我用错了我的问题的关键词:/)，所以我有这个XML：

<questionReponses
xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'
xmlns='http://polytis.fr/studentest'
xsi:schemaLocation='http://polytis.fr/studentest qanda.xsd'>
<questionReponse>
    <categorie>Biologie</categorie>
    <question>Question 1</question>
    <reponse>reponse correcte 1</reponse>
    <mauvaiseReponse>reponse fausse 1.1</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 1.2</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 1.3</mauvaiseReponse>
</questionReponse>
<questionReponse>
    <categorie>Chimie</categorie>
    <question>Question 2</question>
    <reponse>reponse correcte 2</reponse>
    <mauvaiseReponse>reponse fausse 2.1</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 2.2</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 2.3</mauvaiseReponse>
</questionReponse>
<questionReponse>
    <categorie>CultureG</categorie>
    <question>Question 3</question>
    <reponse>reponse correcte 3</reponse>
    <mauvaiseReponse>reponse fausse 3.1</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 3.2</mauvaiseReponse>
    <mauvaiseReponse>reponse fausse 3.3</mauvaiseReponse>
</questionReponse>

​

下面是我的解析器：

try {
        // instanciation du parser
        InputStream in = new FileInputStream(nomFichier);
        XMLInputFactory factory = XMLInputFactory.newInstance();
        XMLStreamReader parser = factory.createXMLStreamReader(in);

        // lecture des evenements
        for (int event = parser.next(); event != XMLStreamConstants.END_DOCUMENT; event = parser.next()) {
            // traitement selon l'evenement
            switch (event) {
                case XMLStreamConstants.START_ELEMENT:
                    break;
                case XMLStreamConstants.END_ELEMENT:
                    if (parser.getLocalName().equals("questionReponse")) {
                        question = new Question(categorieCourante,questionCourante,bonneReponseCourante,mauvaisesReponses);
                        quizz.add(question);
                    }               
                    if (parser.getLocalName().equals("categorie")) {
                        categorieCourante = donneesCourantes;
                    }
                    if (parser.getLocalName().equals("question")) {
                        questionCourante = donneesCourantes;
                    }
                    if (parser.getLocalName().equals("reponse")) {
                        bonneReponseCourante = donneesCourantes;
                    }
                    if (parser.getLocalName().equals("mauvaiseReponse")) {
                        mauvaisesReponses.add(donneesCourantes);
                    }
                    break;
                case XMLStreamConstants.CHARACTERS:
                    donneesCourantes = parser.getText();
                    break;
            } // end switch
        } // end for
        parser.close();
    }

结果并不是预期的那样：

question 1
[categorie = 
Biologie
question = 
Question 1
bonne reponse = 
reponse correcte 1
mauvaises reponse = 
reponse fausse 1.1
reponse fausse 1.2
reponse fausse 1.3
reponse fausse 2.1
reponse fausse 2.2
reponse fausse 2.3
reponse fausse 3.1
reponse fausse 3.2
reponse fausse 3.3


, categorie = 
Chimie
question = 
Question 2
bonne reponse = 
reponse correcte 2
mauvaises reponse = 
reponse fausse 1.1
reponse fausse 1.2
reponse fausse 1.3
reponse fausse 2.1
reponse fausse 2.2
reponse fausse 2.3
reponse fausse 3.1
reponse fausse 3.2
reponse fausse 3.3


, categorie = 
CultureG
question = 
Question 3
bonne reponse = 
reponse correcte 3
mauvaises reponse = 
reponse fausse 1.1
reponse fausse 1.2
reponse fausse 1.3
reponse fausse 2.1
reponse fausse 2.2
reponse fausse 2.3
reponse fausse 3.1
reponse fausse 3.2
reponse fausse 3.3


]

我的三个问题也是一样的。当我解析"mauvaiseReponse“时，所有的"mauvaiseReponse”包都是流和添加的。

我正在寻找的结果是这样的：

question 1
categorie = 
Biologie
question = 
Question 1
bonne reponse = 
reponse correcte 1
mauvaises reponse = 
reponse fausse 1.1
reponse fausse 1.2
reponse fausse 1.3

对不起，如果我的英语不是那么好，我希望你能解决我的问题，并能帮助我解决这个问题。

Answer 1

解释

简单地说，您必须在每个已完成的问题实例上更新您的badAnswers 列表。

我已经为提供的输入xml文件编写了一个示例代码。为了简单起见，我用解决方案在同一个文件中创建了问题类；

    // A - first instantiation of badAnswers list
    List<String> badAnswers = new LinkedList<>();
    for (int event = parser.next(); event != XMLStreamConstants.END_DOCUMENT; event = parser.next()) {

        switch (event) {
            case XMLStreamConstants.START_ELEMENT:
                break;

            case XMLStreamConstants.END_ELEMENT:
                if (parser.getLocalName().equals("questionReponse")) {
                    Question question = new Question(currentCategory, currentQuestion, currentRightAnswer, badAnswers);
                    quiz.add(question);
                    // B - Renew badAnswers after each Question entry insert
                    badAnswers = new LinkedList<>();    
                }   

还请注意，我在这里使用了LinkedList实现来演示您的问题与列表实现无关，它与实现无关。

解码

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.LinkedList;
import java.util.List;

import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

public class Solution {

    public static void main(String[] args)  {
        List<Question> quiz = getQuiz("inputFile.xml");

        printQuiz(quiz);
    }

    public static List<Question> getQuiz(String fileName) {
        List<Question> quiz = null;

        try {
            // parser instantiation
            InputStream in = new FileInputStream(fileName);
            XMLInputFactory factory = XMLInputFactory.newInstance();
            XMLStreamReader parser = factory.createXMLStreamReader(in);

            String currentData = null, currentCategory = null, currentQuestion = null, currentRightAnswer = null;
            quiz = new LinkedList<>();
            List<String> badAnswers = new LinkedList<>();   // first instantiation of badAnswers list
            for (int event = parser.next(); event != XMLStreamConstants.END_DOCUMENT; event = parser.next()) {

                switch (event) {
                    case XMLStreamConstants.START_ELEMENT:
                        break;

                    case XMLStreamConstants.END_ELEMENT:
                        if (parser.getLocalName().equals("questionReponse")) {
                            Question question = new Question(currentCategory, currentQuestion, currentRightAnswer, badAnswers);
                            quiz.add(question);
                            badAnswers = new LinkedList<>();    // Renew badAnswers after each Question entry insert
                        }               
                        if (parser.getLocalName().equals("categorie")) {
                            currentCategory = currentData;
                        }
                        if (parser.getLocalName().equals("question")) {
                            currentQuestion = currentData;
                        }
                        if (parser.getLocalName().equals("reponse")) {
                            currentRightAnswer = currentData;
                        }
                        if (parser.getLocalName().equals("mauvaiseReponse")) {
                            badAnswers.add(currentData);
                        }
                        break;

                    case XMLStreamConstants.CHARACTERS:
                        currentData = parser.getText();
                        break;
                }
            }   // end of for loop
            parser.close();

        } catch (FileNotFoundException | XMLStreamException e) {
            e.printStackTrace();
        }

        return quiz;
    }

    public static void printQuiz(List<Question> quiz) {
        int i = 1;
        for(Question q : quiz) {
            System.out.println("Question    : " + i++);
            System.out.printf("\tCategory   : %s\n" , q.getCurrentCategory());
            System.out.printf("\tQuestion   : %s\n" , q.getCurrentQuestion());
            System.out.printf("\tAnswer     : %s\n" , q.getCurrentRightAnswer());
            System.out.printf("\tBad Answers: %s\n" , q.getBadAnswers());
            System.out.println("***********************\n");
        }
    }

}

class Question {

    private String currentCategory;
    private String currentQuestion;
    private String currentRightAnswer;
    private List<String> badAnswers;

    public Question(String currentCategory, String currentQuestion, String currentRightAnswer, List<String> badAnswers) {
        this.currentCategory = currentCategory;
        this.currentQuestion = currentQuestion;
        this.currentRightAnswer = currentRightAnswer;
        this.badAnswers = badAnswers;
    }

    public String getCurrentCategory() {
        return currentCategory;
    }

    public String getCurrentQuestion() {
        return currentQuestion;
    }

    public String getCurrentRightAnswer() {
        return currentRightAnswer;
    }

    public List<String> getBadAnswers() {
        return badAnswers;
    }

}

演示输出

Question    : 1
    Category   : Biologie
    Question   : Question 1
    Answer     : reponse correcte 1
    Bad Answers: [reponse fausse 1.1, reponse fausse 1.2, reponse fausse 1.3]
***********************

Question    : 2
    Category   : Chimie
    Question   : Question 2
    Answer     : reponse correcte 2
    Bad Answers: [reponse fausse 2.1, reponse fausse 2.2, reponse fausse 2.3]
***********************

Question    : 3
    Category   : CultureG
    Question   : Question 3
    Answer     : reponse correcte 3
    Bad Answers: [reponse fausse 3.1, reponse fausse 3.2, reponse fausse 3.3]
***********************

Answer 2

之所以会发生这种情况，是因为您的所有问题都有相同的mauvaisesReponses列表实例。

您应该在将新实例mauvaisesReponses添加到问题new Question(categorieCourante,questionCourante,bonneReponseCourante,mauvaisesReponses)之后创建它。

question = new Question(categorieCourante,questionCourante,bonneReponseCourante,mauvaisesReponses);
quizz.add(question);
mauvaisesReponses = new ArrayList<>(); //Or what data structure you use for it.