Can't refer to Button through array

I am making a chess game, and I've made the board by piecing together a bunch of buttons, one for each tile on the board.

package game;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;

public class ChessController {

    @FXML 
    private Button
    tile10, tile11, tile12, tile13, tile14, tile15, tile16, tile17,
    tile00, tile01, tile02, tile03, tile04, tile05, tile06, tile07;

    private Button[][] buttonLookup = new Button[][] {
            {tile00, tile01, tile02, tile03, tile04, tile05, tile06, tile07},
            {tile10, tile11, tile12, tile13, tile14, tile15, tile16, tile17}
    };

    @FXML
    private void updateBoard() {
        for (int i = 0; i <= 2; i++) {
        //iterates through rows
            for (int j = 0; j <= 7; j++) {
            //iterates through columns
                System.out.println(buttonLookup[i][j].getId()); //<---- Problem is here
            }
        }
    }
}

When I try to run this I get a NullPointerException, triggered in the line I've marked in the code.

I tried substituting

buttonLookup[i][j]

into

tile00

and this made it work. I also tried with buttonLookup[0][0], and got the same error as with the original code. This leads me to believe I can't refer to the FXML buttons through the array I made to do so. Why not, and is there any way I can do it?

I am trying to change the text on a bunch of buttons, and would like to not hard code that, which is why I'm trying to do it with a loop instead (in the example code I used .getId() instead of .setText("text"), but that was just for testing purposes.