How to find a contour using java in android studio without using any external libraries like openCV

Question

I'm new for image processing, I'm tring to find a contour of an image without using external libraries.

public static List<Contour> findContours(Bitmap edgeImage) {
        List<Contour> contours = new ArrayList<>();

        int width = edgeImage.getWidth();
        int height = edgeImage.getHeight();

        boolean[][] visited = new boolean[width][height];

        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                if (!visited[x][y] && isEdgePixel(edgeImage, x, y)) {
                    Contour contour = traceContour(edgeImage, visited, x, y);
                    contours.add(contour);
                }
            }
        }

        return contours;
    }

    private static Contour traceContour(Bitmap edgeImage, boolean[][] visited, int startX, int startY) {
        List<Point> contourPoints = new ArrayList<>();

        // Depth-first search to trace contour
        dfs(edgeImage, visited, startX, startY, contourPoints);

        return new Contour(contourPoints);
    }

    private static void dfs(Bitmap edgeImage, boolean[][] visited, int x, int y, List<Point> contourPoints) {
        int width = edgeImage.getWidth();
        int height = edgeImage.getHeight();

        if (x < 0 || x >= width || y < 0 || y >= height || visited[x][y] || !isEdgePixel(edgeImage, x, y)) {
            return;
        }

        visited[x][y] = true;
        contourPoints.add(new Point(x, y));

        // Visit neighbors
        dfs(edgeImage, visited, x + 1, y, contourPoints);
        dfs(edgeImage, visited, x - 1, y, contourPoints);
        dfs(edgeImage, visited, x, y + 1, contourPoints);
        dfs(edgeImage, visited, x, y - 1, contourPoints);        
    }

    private static boolean isEdgePixel(Bitmap edgeImage, int x, int y) {
        // Customize this method based on how edges are represented in your edge image
        // For simplicity, assuming black pixels represent edges
        int pixelValue = edgeImage.getPixel(x, y);
        return Color.red(pixelValue) == 0;  // Assuming black edges
    }

I use the above code for finding a contour but the code is crashed after calling a function dfs

I don't know the reason.

please any one help me for resolove this issue