Java - Access original type of object in ArrayList

I'm working with a double array and need to be able to calculate the surrounding <8 neighbors of one tile from class Tile. Since I want to know them individually, Tile contains 8 setter-methods that accept Tile as a parameter for every direction respectively. So first I'm iterating through the neighbors of a given tile and add them to an ArrayList. Now I want to pass those elements into the setter-methods but they won't accept it because it's not a Tile but a List<Tile> How can I work around this? I tried changing the setter-Method to expect a List but that didn't change anything. Or do I maybe need to restructure my entire approach? For this I was looking at a tile that definitely had all 8 neighbors, I need to think of catching those at the edge who don't have as much neighbors once this works in general.

private void calculateNeighbors (int x, int y){
    System.out.print("The neighbors of " + getTile(x,y));

    List<Tile> neighbors = new ArrayList<>();

    int[] coordinates = new int[]{
            -1,-1, 
            -1, 0,
            -1, 1,
            0,-1,
            0, 1,
            1,-1,
            1, 0,
            1, 1
    };

    for (int i = 0; i < coordinates.length; i++) {
        int columnX = coordinates[i];
        int rowY = coordinates[++i];

        int nextX = x + columnX;
        int nextY = y + rowY;

        if (nextX >= 0 && nextX < getListOfTiles().length
                && nextY >= 0 && nextY < getListOfTiles().length) {
                neighbors.add(getTile(nextX, nextY));
        }
    }
    //this here isn't working
    tile.setTopLeft(neighbors[0]);
    tile.setTop(neighbors[1]);
    //etc
    }
}