从txt.file中读取数字并生成2d数组

Question

例如我们有文件(“Test2”)包含:

1 2 3 4 5
1 2 3 4 0
1 2 3 0 0
1 2 0 0 0
1 0 0 0 0
1 2 0 0 0
1 2 3 0 0
1 2 3 4 0
1 2 3 4 5 

我们想从文件读取它。在这个例子中

   public class Read2 {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner s = new Scanner(new FileReader("Test2"));
        int[][] array = new int[9][5];
        while (s.hasNextInt()) {
            for (int i = 0; i < array.length; i++) {
                String[] numbers = s.nextLine().split(" ");
                for (int j = 0; j < array[i].length; j++) {
                    array[i][j] = Integer.parseInt(numbers[j]);
                }
            }
        }
        for (int[] x : array) {
            System.out.println(Arrays.toString(x));
        }
         // It is a normal int[][] and i can use their data for calculations.
        System.out.println(array[0][3] + array[7][2]);
    }
} 

// Output
[1, 2, 3, 4, 5]
[1, 2, 3, 4, 0]
[1, 2, 3, 0, 0]
[1, 2, 0, 0, 0]
[1, 0, 0, 0, 0]
[1, 2, 0, 0, 0]
[1, 2, 3, 0, 0]
[1, 2, 3, 4, 0]
[1, 2, 3, 4, 5]
7//result from sum

我的问题是:如果我有一个x =行，y =列(未知大小)的文件，我想从文件中读取数字，并将它们放入2d数组，就像前面的例子一样。我应该写什么类型的代码？

Answer 1

正如@Andy Turner所说，使用＜code＞列表

public class Read2 {

    public static void main(String[] args) throws FileNotFoundException {
        Scanner s = new Scanner(new FileReader("Test2"));
        List<List<Integer>> list = new ArrayList<>();
        // scan digits in every line
        while (s.hasNextLine()) {
            String str = s.nextLine();
            String[] strSplitArr = str.split(" ");
          list.add(Arrays.stream(strSplitArr)
              .map(Integer::parseInt)
              .collect(Collectors.toList()));
        }
        for (List<Integer> integersInOneLine : list) {
            System.out.println(integersInOneLine.stream()
                      .map(Object::toString)
                      .collect(Collectors.joining(", ", "[", "]")));
            System.out.println();
        }
    }
}

Answer 2

这是一个解决方案使用流API:

var arr = new BufferedReader(new FileReader("PATH/TO/FILE")).lines()
                .map(s -> s.split("\\s+"))
                .map(s -> Stream.of(s)
                        .map(Integer::parseInt)
                        .toArray(Integer[]::new))
                .toArray(Integer[][]::new);