int tileSize = 50;
int[][] grid = new int[3][5];

int xpx = 0,ypx = 0;

for (int y = 0; y <= grid.length; y++) {

    for (int x = 0; x <= grid[0].length; x++) {

        // Replace by grid[yval][xval] = Rect(xpx,ypx,tileSize,tileSize);
        System.out.println("X Coord:" + xpx + "\nY Coord:" + ypx + "\nX,Y Array:" + x + "," + y);

        xpx += tileSize;

    }
    xpx = 0;
    ypx += tileSize;
}