JavaFX memory matching game

hello-view.hxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.HBox?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Font?>


<AnchorPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/15.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.example.memorymatchinggame.HelloController">
   <children>
      <VBox layoutX="160.0" layoutY="60.0" prefHeight="300.0" prefWidth="300.0">
         <children>
            <HBox prefHeight="100.0" prefWidth="300.0">
               <children>
                  <Button fx:id="button0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button fx:id="button1" layoutX="10.0" layoutY="10.0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button fx:id="button2" layoutX="235.0" layoutY="10.0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
               </children>
            </HBox>
            <HBox layoutX="10.0" layoutY="10.0" prefHeight="100.0" prefWidth="300.0">
               <children>
                  <Button fx:id="button3" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button fx:id="button4" layoutX="10.0" layoutY="10.0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button fx:id="button5" layoutX="110.0" layoutY="10.0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
               </children>
            </HBox>
            <HBox layoutX="10.0" layoutY="110.0" prefHeight="100.0" prefWidth="300.0">
               <children>
                  <Button fx:id="button6" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button fx:id="button7" layoutX="10.0" layoutY="10.0" mnemonicParsing="false" onAction="#buttonClicked" prefHeight="100.0" prefWidth="100.0">
                     <font>
                        <Font size="32.0" />
                     </font>
                  </Button>
                  <Button layoutX="110.0" layoutY="10.0" mnemonicParsing="false" prefHeight="100.0" prefWidth="100.0" style="-fx-background-color: #c61a09;" />
               </children>
            </HBox>
         </children>
      </VBox>
   </children>
</AnchorPane>

HelloApplication.java

package com.example.memorymatchinggame;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.stage.Stage;

import java.io.IOException;

public class HelloApplication extends Application {
    @Override
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("hello-view.fxml"));
        Scene scene = new Scene(fxmlLoader.load());
        stage.setTitle("Memory Game");
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}

HelloController.java

package com.example.memorymatchinggame;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Control;
import javafx.util.Duration;

import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.ResourceBundle;

public class HelloController implements Initializable {

    ArrayList<Button> buttons = new ArrayList<>();

    MemoryGame memoryGame = new MemoryGame();

    @FXML
    private Button button0;
    @FXML
    private Button button1;
    @FXML
    private Button button2;
    @FXML
    private Button button3;
    @FXML
    private Button button4;
    @FXML
    private Button button5;
    @FXML
    private Button button6;
    @FXML
    private Button button7;

    Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(1.5), e -> hideButtons()));

    private boolean firstButtonClicked = false;

    private int firstButtonIndex;
    private int secondButtonIndex;
    private boolean match;

    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        memoryGame.setupGame();

        buttons.addAll(Arrays.asList(button0, button1, button2, button3, button4,
                button5, button6, button7));
    }

    @FXML
    void buttonClicked(ActionEvent event) {
        if(!firstButtonClicked){
            //If next turn is started before old buttons are hidden
            if(!match){
                hideButtons();
                timeline.stop();
            }
            match = false;
            firstButtonClicked = true;

            //Get clicked button memory letter
            String buttonId = ((Control)event.getSource()).getId();
            firstButtonIndex = Integer.parseInt(buttonId.substring(buttonId.length() - 1));

            //Change clicked button text
            buttons.get(firstButtonIndex).setText(memoryGame.getOptionAtIndex(firstButtonIndex));

            return;
        }

        //Get clicked button memory letter
        String buttonId = ((Control)event.getSource()).getId();
        secondButtonIndex = Integer.parseInt(buttonId.substring(buttonId.length() - 1));

        //Change clicked button text
        buttons.get(secondButtonIndex).setText(memoryGame.getOptionAtIndex(secondButtonIndex));

        firstButtonClicked = false;

        //Check if the two clicked button match
        if(memoryGame.checkTwoPositions(firstButtonIndex,secondButtonIndex)){
            System.out.println("Match");
            match = true;
            return;
        }

        timeline.play();
    }

    private void hideButtons(){
        buttons.get(firstButtonIndex).setText("");
        buttons.get(secondButtonIndex).setText("");
    }

}

MemoryGame.java

package com.example.memorymatchinggame;

import java.util.*;

public class MemoryGame {

    private int turns = 0;
    private int points = 0;
    private final int boardLength = 3;
    private final int boardSize = boardLength * boardLength;
    private final Random random = new Random();

    private final ArrayList<String> memoryBoard = new ArrayList<>(Arrays.asList("", "", "", "", "", "", "", ""));
    private final ArrayList<String> memoryOptions = new ArrayList<>(Arrays.asList("a", "a", "b", "b", "c", "c", "d", "d"));

    public void setupGame(){
        setupMemoryBoard();
        System.out.println(memoryBoard);
    }

    public String getOptionAtIndex(int index){
        return memoryBoard.get(index);
    }

    private void setupMemoryBoard(){
        for (int i = 0; i < boardSize - 1; i++) {
            String memoryOption = memoryOptions.get(i);
            int position = random.nextInt(boardSize - 1);

            while (!Objects.equals(memoryBoard.get(position), "")){
                position = random.nextInt(boardSize - 1);
            }
            memoryBoard.set(position, memoryOption);
        }
    }

    public boolean checkTwoPositions(int firstIndex, int secondIndex){
       return memoryBoard.get(firstIndex).equals(memoryBoard.get(secondIndex));
    }
}