JavaFX snake game

Controller.java

package sample;

import javafx.animation.Animation;
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.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.util.Duration;

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

public class Controller implements Initializable {

    //A snake body part is 50x50
    private final Double snakeSize = 50.;
    //The head of the snake is created, at position (250,250)
    private final Rectangle snakeHead = new Rectangle(250,250,snakeSize,snakeSize);
    //First snake tail created behind the head of the snake
    Rectangle snakeTail_1 = new Rectangle(snakeHead.getX() - snakeSize,snakeHead.getY(),snakeSize,snakeSize);

    //x and y position of the snake head different from starting position
    double xPos = snakeHead.getLayoutX();
    double yPos = snakeHead.getLayoutY();

    //Direction snake is moving at start
    private Direction direction = Direction.RIGHT;

    //List of all position of thew snake head
    private final List<Position> positions = new ArrayList<>();

    //List of all snake body parts
    private final ArrayList<Rectangle> snakeBody = new ArrayList<>();

    //Game ticks is how many times the snake have moved
    private int gameTicks = 0;

    @FXML
    private AnchorPane anchorPane;
    @FXML
    private Button startButton;

    //Timeline that is running the game every time the KeyFrame is called (0.3 s)
    Timeline timeline = new Timeline(new KeyFrame(Duration.seconds(0.3),e ->{
        positions.add(new Position(snakeHead.getX() +xPos, snakeHead.getY() + yPos));
        moveSnakeHead(snakeHead);
        for (int i = 1; i < snakeBody.size(); i++) {
            moveSnakeTail(snakeBody.get(i),i);
        }
        gameTicks++;
    }));

    //Method called after the stage is loaded
    @Override
    public void initialize(URL url, ResourceBundle resourceBundle) {
        snakeBody.add(snakeHead);
        snakeHead.setFill(Color.RED);

        timeline.setCycleCount(Animation.INDEFINITE);
        timeline.play();

        snakeBody.add(snakeTail_1);

        anchorPane.getChildren().addAll(snakeHead,snakeTail_1);
    }


    @FXML
    void start(MouseEvent event) {
        //Restart not implemented yet
    }

    //Change position with key pressed
    @FXML
    void moveSquareKeyPressed(KeyEvent event) {
        if(event.getCode().equals(KeyCode.W) && direction != Direction.DOWN){
            direction = Direction.UP;
        } else if(event.getCode().equals(KeyCode.S) && direction != Direction.UP){
            direction = Direction.DOWN;
        }else if(event.getCode().equals(KeyCode.A) && direction != Direction.RIGHT){
            direction = Direction.LEFT;
        }else if(event.getCode().equals(KeyCode.D) && direction != Direction.LEFT){
            direction = Direction.RIGHT;
        }
    }

    //Create another snake body part
    @FXML
    void addBodyPart(ActionEvent event) {
        addSnakeTail();
    }

    //Snake head is moved in the direction specified
    private void moveSnakeHead(Rectangle snakeHead){
        if(direction.equals(Direction.RIGHT)){
            xPos = xPos + snakeSize;
            snakeHead.setTranslateX(xPos);
        } else if(direction.equals(Direction.LEFT)) {
            xPos = xPos - snakeSize;
            snakeHead.setTranslateX(xPos);
        }else if(direction.equals(Direction.UP)) {
            yPos = yPos - snakeSize;
            snakeHead.setTranslateY(yPos);
        }else if(direction.equals(Direction.DOWN)) {
            yPos = yPos + snakeSize;
            snakeHead.setTranslateY(yPos);
        }
    }

    //A specific tail is moved to the position of the head x game ticks after the head was there
    private void moveSnakeTail(Rectangle snakeTail, int tailNumber){
        double yPos = positions.get(gameTicks - tailNumber + 1).getYPos() - snakeTail.getY();
        double xPos = positions.get(gameTicks - tailNumber + 1).getXPos() - snakeTail.getX();
        snakeTail.setTranslateX(xPos);
        snakeTail.setTranslateY(yPos);
    }

    //New snake tail is created and added to the snake and the anchor pane
    private void addSnakeTail(){
        Rectangle rectangle = snakeBody.get(snakeBody.size() - 1);
        Rectangle snakeTail = new Rectangle(
                snakeBody.get(1).getX() + xPos + snakeSize,
                snakeBody.get(1).getY() + yPos,
                snakeSize,snakeSize);
        snakeBody.add(snakeTail);
        anchorPane.getChildren().add(snakeTail);
    }
}

Direction.java

package sample;

public enum Direction {
    UP, DOWN, RIGHT, LEFT
}

Main.java

package sample;

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

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }


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

Position.java

package sample;

public class Position {
    private final double xPos;
    private final double yPos;

    public Position(double xPos, double yPos) {
        this.xPos = xPos;
        this.yPos = yPos;
    }

    public double getXPos() {
        return xPos;
    }

    public double getYPos() {
        return yPos;
    }

    @Override
    public String toString() {
        return "Position{" +
                "xPos=" + xPos +
                ", yPos=" + yPos +
                '}';
    }
}

sample.fxml

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>


<AnchorPane fx:id="anchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" onKeyPressed="#moveSquareKeyPressed" prefHeight="600.0" prefWidth="600.0" style="-fx-background-color: #EAF4D3;" xmlns="http://javafx.com/javafx/15.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
   <children>
      <Button fx:id="startButton" layoutX="32.0" layoutY="34.0" mnemonicParsing="false" onKeyPressed="#moveSquareKeyPressed" onMouseClicked="#start" text="Restart" />
      <Button layoutX="517.0" layoutY="34.0" mnemonicParsing="false" onAction="#addBodyPart" text="Add" />
   </children>
</AnchorPane>