Read a matrix from a txt and store it in a 2D array in java

So I'm trying put a matrix from a txt file into a variable and I have though about using an Array called value[][].

for example the file could be:

0 2 8 1
4 1 6 2
2 1 4 7
2 4 7 9

And the value of value[2][1] would be 6.

How would I go about reading the file and filling the array with the numbers in the correct positions?

Solution with undefined matrix length:

int[][] value = null;
//you can use relative path or full path here
File file = new File("file-name.txt");
try {
    Scanner sizeScanner = new Scanner(file);
    String[] temp = sizeScanner.nextLine().split(" ");
    sizeScanner.close();
    int nMatrix = temp.length;

    Scanner scanner = new Scanner(file);
    value = new int[nMatrix][nMatrix];
    for (int i = 0; i < nMatrix; i++) {
        String[] numbers = scanner.nextLine().split(" ");
        for (int j = 0; j < nMatrix; j++) {
            value[i][j] = Integer.parseInt(numbers[j]);
        }
    }
    scanner.close();
} catch (FileNotFoundException e) {
    e.printStackTrace();
}