Java Advanced - The Matrix

import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Scanner;

public class TheMatrix {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int[] ints = Arrays.stream(scanner.nextLine().split("\\s")).mapToInt(Integer::parseInt).toArray();
        int rows = ints[0];
        int cols = ints[1];

        char[][] matrix = new char[rows][cols];
        for (int i = 0; i < rows; i++) {
            String[] strings = scanner.nextLine().split("\\s");
            for (int j = 0; j < cols; j++) {
                matrix[i][j] = strings[j].charAt(0);
            }
        }

        char fillChar = scanner.nextLine().charAt(0);
        ints = Arrays.stream(scanner.nextLine().split("\\s")).mapToInt(Integer::parseInt).toArray();
        int startRow = ints[0];
        int startCol = ints[1];
        char startChar = matrix[startRow][startCol];

        ArrayDeque<String> stack = new ArrayDeque<>();
        stack.push(startRow + " " + startCol);
        while (!stack.isEmpty()) {
            String node = stack.pop();
            ints = Arrays.stream(node.split("\\s")).mapToInt(Integer::parseInt).toArray();
            startRow = ints[0];
            startCol = ints[1];
            matrix[startRow][startCol] = fillChar;
            if (canReachUp(matrix, startRow - 1, startCol, startChar)) {
                stack.push(startRow - 1 + " " + startCol);
            }
            if (canReachDown(matrix, startRow + 1, startCol, startChar)) {
                stack.push(startRow + 1 + " " + startCol);
            }
            if (canReachLeft(matrix, startRow, startCol - 1, startChar)) {
                stack.push(startRow + " " + (startCol - 1));
            }
            if (canReachRight(matrix, startRow, startCol + 1, startChar)) {
                stack.push(startRow + " " + (startCol + 1));
            }
        }

        for (char[] chars : matrix) {
            for (char aChar : chars) {
                System.out.print(aChar);
            }
            System.out.println();
        }
    }

    private static boolean canReachUp(char[][] matrix, int row, int col, char startChar) {
        return row >= 0 && matrix[row][col] == startChar;
    }

    private static boolean canReachDown(char[][] matrix, int row, int col, char startChar) {
        return row < matrix.length && matrix[row][col] == startChar;
    }

    private static boolean canReachLeft(char[][] matrix, int row, int col, char startChar) {
        return col >= 0 && matrix[row][col] == startChar;
    }

    private static boolean canReachRight(char[][] matrix, int row, int col, char startChar) {
        return col < matrix[row].length && matrix[row][col] == startChar;
    }
}