java - 如何在 Java 中将数字文件读入数组列表

Question

我希望能够从类似以下内容的文件中读取 map :

0, 0, 0, 0, 0

0, 0, 1, 0, 0

0, 1, 1, 1, 1

0, 1, 1, 1, 0

0, 0, 1, 1, 0

并创建一个如下所示的数组列表:

{[0, 0, 0, 0, 0],

[0, 0, 1, 0, 0],

[0, 1, 1, 1, 1],

[0, 1, 1, 1, 0],

[0, 0, 1, 1, 0]}

我尝试过使用 br.readLine() 但它似乎被卡住了，但没有在中间抛出错误。

public static int[][] loadFile() throws IOException{

    FileReader in = new FileReader(Main.currentFilePath + Main.currentFile);
    BufferedReader br = new BufferedReader(in);
    String line;
    int [] intArray = {};
    int [][] fileArray = {};
    int j = 0;
    while ((line = br.readLine()) != null) {
        List<String> stringList = new ArrayList<String>(Arrays.asList(line.split(",")));
        String[] stringArray = stringList.toArray(new String[0]);
        List<Integer> intList = new ArrayList<Integer>();
        System.out.println("RRRRR");
        for(int i = 0; i < stringList.size(); i++) {
            Scanner scanner = new Scanner(stringArray[i]);
            System.out.println("GGGGG");
            while (scanner.hasNextInt()) {
                intList.add(scanner.nextInt());
                intArray = intList.parallelStream().mapToInt(Integer::intValue).toArray();
                System.out.println("FFFF");
            }
            System.out.println(fileArray[j][i]);
            fileArray[j][i] = intArray[i];
        }
        j++;
    }
    return fileArray;
    
}

Answer 1

基本问题是，您声明了一个 0 长度的数组(无元素)，这使得无法向其中添加任何元素。

int [][] fileArray = {};

除非您事先确切地知道所需的行/列数，否则数组不是很有帮助，相反，您可以使用某种List，例如...

List<int[]> rows = new ArrayList<>(5);
int maxCols = 0;
try (BufferedReader br = new BufferedReader(new FileReader(new File("Test.txt")))) {
    String text = null;
    while ((text = br.readLine()) != null) {
        System.out.println(text);
        String[] parts = text.split(",");
        int[] row = new int[parts.length];
        maxCols = Math.max(maxCols, row.length);
        for (int col = 0; col < parts.length; col++) {
            row[col] = Integer.parseInt(parts[col].trim());
        }
        rows.add(row);
    }
} catch (IOException ex) {
    ex.printStackTrace();
}

int[][] map = new int[rows.size()][maxCols];
for (int row = 0; row < rows.size(); row++) {
    map[row] = rows.get(row);
}

我的“个人”直觉是根本不用理会数组，只需使用复合List...

List<List<Integer>> rows = new ArrayList<>(5);
try (BufferedReader br = new BufferedReader(new FileReader(new File("Test.txt")))) {
    String text = null;
    while ((text = br.readLine()) != null) {
        System.out.println(text);
        String[] parts = text.split(",");
        List<Integer> row = new ArrayList<>(parts.length);
        for (String value : parts) {
            row.add(Integer.parseInt(value.trim()));
        }
        rows.add(row);
    }
} catch (IOException ex) {
    ex.printStackTrace();
}