在Java中将逗号分隔的文件读取到多维数组中

Question

我要将选择题列表读取为Java中的多维数组，文件格式为:Question,answer1,answer2,answer3,answer4,correctanswer。

一公里有多少米?1、10100、1000 4彩虹童谣里没有哪一种颜色?,蓝色,粉色,黑色,橙色,3一个足球队在场上有多少名队员?10、11、12、13、2

所以我希望数组的格式是Question[][]如果n为1那么Question[n][1]将是CSV文件中的第一个问题，然后选择一个问题，我可以将n更改为我想要的任何值

我不知道会有多少问题，它们会不断地从CSV文件中添加或删除，所以不会有一个静态的数量。问题是如何简单地从CSV文件中加载所有问题?

Answer 1

当您必须为数据层次结构创建一个二维数组时，您可能应该为它创建一个合理的模型。

这里是一个快速(和肮脏)的模型(为了打字速度，丢弃了setter):

问卷类:

/**
 * Facilitates an entire questionnaire
 */
public class Questionnaire extends ArrayList<Question> {
    /**
     * This questionnaire's name
     */
    private String name;
    /**
     * Creates a new questionnaire using the specified name
     * @param name  The name of this questionnaire
     */
    public Questionnaire(String name) {
        this.name = name;
    }
    /**
     * Returns the name of this questionnaire
     */
    public String getName() {
        return name;
    }
}

问题类:

/**
 * Facilitates a question and its answers
 */
public class Question extends ArrayList<Answer> {
    /**
     * The question's text
     */
    private String text;
    /**
     * Constructs a new question using the specified text
     * @param text  The question's text
     */
    public Question(String text) {
        this.text = test;
    }
    /**
     * Returns this question's text
     */
    public String getText() {
        return text;
    }
}

回答类:

/**
 * Facilitates an answer
 */
public class Answer {
    /**
     * The answer's text
     */
    private String text;
    /**
     * Whether or not this answer is correct
     */
    private boolean correct;
    /**
     * Constructs a new answer using the specified settings
     * @param text          The text of this answer
     * @param correct       Whether or not this answer is correct
     */
    public Answer(String text, boolean correct) {
        this.text = text;
        this.correct = correct;
    }
    /**
     * Returns this answer's text
     */
    public String getText() {
        return text;
    }
    /**
     * Whether or not this answer is correct
     */
    public boolean isCorrect() {
        return correct;
    }
}

的用法如下:

// Create a new questionnaire
Questionnaire questionnaire = new Questionnaire("The awesome questionnaire");
// Create a question and add answers to it
Question question = new Question("How awesome is this questionnaire?");
question.add(new Answer("It's pretty awesome", false));
question.add(new Answer("It's really awesome", false));
question.add(new Answer("It's so awesome my mind blows off!", true));
// Add the question to the questionnaire
questionnaire.add(question);

迭代它非常容易:

// Iterate over the questions within the questionnaire
for(Question question : questionnaire) {
    // Print the question's text
    System.out.println(question.getText());
    // Go over each answer in this question
    for(Answer answer : question) {
        // Print the question's text
        System.out.println(answer.getText());
    }
}

你也可以只迭代其中的一部分:

// Iterate over the third to fifth question
for (int questionIndex = 2; questionIndex < 5; questionIndex ++) {
    // Get the current question
    Question question = questionnaire.get(questionIndex);
    // Iterate over all of the answers
    for (int answerIndex = 0; answerIndex < question.size(); answerIndex++) {
        // Get the current answer
        Answer answer = question.get(answerIndex);
    }
}

使用您描述的格式将文件读取到模型中可以通过以下方式完成:

// Create a new questionnaire
Questionnaire questionnaire = new Questionnaire("My awesome questionnaire");
// Lets scan the file and load it up to the questionnaire
Scanner scanner = new Scanner(new File("myfile.txt"));
// Read lines from that file and split it into tokens
String line, tokens[];
int tokenIndex;
while (scanner.hasNextLine() && (line = scanner.nextLine()) != null) {
    tokens = line.split(",");
    // Create the question taking the first token as its text
    Question question = new Question(tokens[0]);
    // Go over the tokens, from the first index to the one before last
    for (tokenIndex = 1; tokenIndex < tokens.length-1; tokenIndex++) {
        // Add the incorrect answer to the question
        question.add(new Answer(tokens[tokenIndex], false));
    }
    // Add the last question (correct one)
    question.add(new Answer(tokens[tokenIndex],true));
}
// Tada! questionnaire is now a complete questionnaire.

Answer 2

最简单的方法是创建一个ArrayList或数组。这看起来很复杂，但使用ArrayList意味着您不必担心问题的数量。

ArrayList<String[]> questions = new ArrayList<String[]>();
// Create the object to contain the questions.
Scanner s = new Scanner(new File("path to file"));
// Create a scanner object to go through each line in the file.
while(s.hasNextLine()) {
   // While lines still exist inside the file that haven't been loaded..
   questions.add(s.nextLine().split(","));
   // Load the array of values, splitting at the comma.
}

最后，您将得到一个ArrayList对象，其中每个条目都是一个String[]，其长度与每行上的令牌数量相同。

编辑

正如在这个答案的评论中提到的，您可以简单地调用ArrayList类中的toArray方法，以获得多维数组。

Answer 3

你需要设置一个嵌套的for循环来处理这个:

for(i = 0; i < number_of_questions; i++)
{
    line_array = current_input_line.split(",")
    Questions[i] = line_array[0]
    for(j = 1; j < line_array.length; j++)
    {
        Questions[i][j] = line_array[j];
    }
}