Question

我需要帮助将数据从4 ArrayLists传输到多维数组。请查看我的变量中的注释。

我需要以这种格式将所有arraylists的数据放入card[][]：

card[][] = {{questions,answers,category,essay}};

代码：

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFileChooser;

public class Test {
    static JFileChooser chooser = new JFileChooser();

     //these need to go into card[][]
    static List<String> questions = new ArrayList<String>();
    static List<String> answers = new ArrayList<String>();
    static List<String> categories = new ArrayList<String>();
    static List<String> essays = new ArrayList<String>();


    static String[][] card;

    public static void main(String[] args) {

        OpenFile();

    }

    public static void OpenFile() {
        int retrival = chooser.showOpenDialog(null);
        if (retrival == JFileChooser.APPROVE_OPTION) {
            String line;

            try (BufferedReader br = new BufferedReader(new FileReader(
                    chooser.getSelectedFile()))) {
                while ((line = br.readLine()) != null) {
                    String[] splitted = line.split("Question: ");
                    String[] splittedAnswer = line.split("Answer: ");
                    String[] splittedCategory = line.split("Category: ");
                    String[] splittedEssay = line
                            .split("Essay Question Possibility: ");

                    if (splittedAnswer.length == 2) {
                        answers.add(splittedAnswer[1]);
                    } else if (splitted.length == 2) {
                        questions.add(splitted[1]);

                    } else if (splittedCategory.length == 2) {
                        categories.add(splittedCategory[1]);

                    } else if (splittedEssay.length == 2) {
                        essays.add(splittedEssay[1]);

                    }

                }
                br.close();

            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}

Answer 1

假设所有数组列表大小相同，您可以按照以下方式执行，

String[][] card = new String[4][questions.size()];
for (int i = 0; i < questions.size(); i++) {
    card[0][i] = questions.get(i);
    card[1][i] = answers.get(i);
    card[2][i] = categories.get(i);
    card[3][i] = essays.get(i);
}

的建议 的

但我建议您使用面向对象的数据结构来保存数据。不建议使用多个列表或2D数组。

您可以简单地将结构定义为

public class Card { String question; String answer; String categories; String essay; }

你有这个清单。

List<Card> cards = new ArrayList<Cards>();

Answer 2

试试这个，

            String  card[][] ;
            List<String> questions = new ArrayList<String>();
            List<String> answers = new ArrayList<String>();
            List<String> categories = new ArrayList<String>();
            List<String> essays = new ArrayList<String>();
            questions.add("11");
            questions.add("12");
            questions.add("13");

            answers.add("21");
            answers.add("22");
            answers.add("23");

            categories.add("31");
            categories.add("32");
            categories.add("33");

            essays.add("41");
            essays.add("42");
            essays.add("43");

            card=new String [essays.size()][4];
            for(int i=0;i<questions.size();i++)
            {
               card[i][0]=questions.get(i);
               card[i][1]=answers.get(i);
               card[i][2]=categories.get(i);
               card[i][3]=essays.get(i);
            }

输出

{{“11”，“21”，“31”，“41”}，{“12”，“22”，“32”，“42”}，{“13”，“23 “，”33“，”43“}，...};

Answer 3

我认为所有的arraylists都有一个尺寸。如果'不'你首先应该找到最小尺寸的arraylists然后使用它而不是questions.size（）：

card = new String[questions.size()][4];

for (int i = 0; i < card.length; i++){
    card[i][0] = questions.get(i);
    card[i][1] = answers.get(i);
    card[i][2] = categories.get(i);
    card[i][3] = essays.get(i);
}

结果将如下：

{{“q1”，“a1”，“c1”，“e1”}，{“q2”，“a2”，“c2”，“e2”}，{“q3”，“a3”，“ c3“，”e3“}，{”q4“，”a4“，”c4“，”e4“}，...};

将数据从多个arraylist传输到多维数组

3 个答案: