Reducing A Matrix Into A Reduced Row Echelon Form

[Kelvin Okornoe]

Am currently working on a project from JetBrains Academy which requires me to read a file containing a matrix and reduce it into reduced row echelon form.
The project requirement can be found here https://hyperskill.org/projects/40/stages/211/implement

This is my current implementation, it only reads the file into two dimensional integer array.

Any recommendations to make the current implementation robust will be appreciated.

package solver;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

public class Matrix {
    File file = new File("../Linear Equations Solver/Linear Equations Solver/task/src/solver/in.txt");

    //reads the content of a file and converts it into a matrix.
    public int[][] convertFileToMatrix() throws IOException {
        int[][] matrix;
        try (BufferedReader br = new BufferedReader(new FileReader(file))) {
            int size = Integer.parseInt(br.readLine());
            matrix = new int[size][];
            for (int z = 0; z < size; z++) {
                String[] line = br.readLine().split("\\s");
                int[] arr = new int[line.length];
                for (int i = 0; i < line.length; i++) {
                    arr[i] = Integer.parseInt(line[i]);
                }
                matrix[z] = arr;
            }
        }
        return matrix;
    }
}

This how the content of the file looks like
The first line determines the row length of the matrix
3
1 1 2 9
2 4 -3 1
3 6 -5 0

Thank you.

[Junilu Lacar]

I would have used a Scanner and Scanner.nextInt() to eliminate the need to do readLine.split() and Integer.parseInt()--that's just too much hoop-jumping for my taste.

[Piet Souris]

Nothing wrong with your code, but I would use this:

var path = Paths.get("...");    // where the input file is located
var matrix = Files.lines(path)
    .skip(1)
    .map(string -> convertToIntArray(string))
    .toArray(int[][]::new)
;

private int[] convertToIntArray(String... s) {
    return Arrays.stream(s).mapToInt(Integer::parseInt).toArray();
}

The method Files.lines may throw an IOException, so either this code must run in a try/catch block, or the method must be declared to throw such an Exception.

[Piet Souris]

Oops... when writing the above code I started from a wrong example. Sorry. I meant this code:

var matrix = Files.lines(path)
    .skip(1)
    .map(string -> convertToIntArray(string.split("\\s+")))
    .toArray(int[][]::new)
;

private static int[] convertToIntArray(String... s) {
    return Arrays.stream(s).mapToInt(Integer::parseInt).toArray();
}

[Kelvin Okornoe]

Thank you for the suggestion so far, I have noted them.
Am still working on the program and I will be posting it here for more reviews.
Thank you.