Подход к ООП

import java.util.Random;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.TextAlignment;
import javafx.stage.Stage;
import javafx.util.Duration;
import logic.HeroRacket;
 
public class Tennis extends Application {
 
    private static final int width = 800;
    private static final int height = 600;
 
    private static final int PLAYER_HEIGHT = 100;
    private static final int PLAYER_WIDTH = 15;
 
    private static final double BALL_R = 15;
    private int ballYSpeed = 1;
    private int ballXSpeed = 1;
 
    private int playerOneXPos = 0;
    private double playerOneYPos = height / 2;
 
    private double playerTwoXPos = width - PLAYER_WIDTH;
    private double playerTwoYPos = height / 2;
 
    private double ballXPos = width / 2;
    private double ballYPos = height / 2;
 
    private int scoreP1 = 0;
    private int scoreP2 = 0;
 
    private boolean gameStarted;
 
 
    public void start(Stage stage) {
        Canvas canvas = new Canvas(width, height);
        GraphicsContext gc = canvas.getGraphicsContext2D();
        Timeline tl = new Timeline(new KeyFrame(Duration.millis(10), e -> run(gc)));
        tl.setCycleCount(Timeline.INDEFINITE);
        canvas.setOnMouseMoved(e ->  playerOneYPos  = e.getY());
        canvas.setOnMouseClicked(e ->  gameStarted = true);
        stage.setScene(new Scene(new StackPane(canvas)));
        stage.show();
        tl.play();
    }
 
    private void field(GraphicsContext gc){
        gc.setFill(Color.GREEN);
        gc.fillRect(0, 0, width, height);
        gc.setFill(Color.WHITE);
        gc.setFont(Font.font(25));
    }
    private void showTextForGame(GraphicsContext gc){
        gc.setStroke(Color.BLACK);
        gc.setTextAlign(TextAlignment.CENTER);
        gc.strokeText("Click to Start", width / 2, height / 2);
    }
    private void run(GraphicsContext gc) {
        field(gc);
 
        if(gameStarted) {
            ballXPos+=ballXSpeed;
            ballYPos+=ballYSpeed;
            if(ballXPos < width - width  / 4) {
                playerTwoYPos = ballYPos - PLAYER_HEIGHT / 2;
            }  else {
                playerTwoYPos =  ballYPos > playerTwoYPos + PLAYER_HEIGHT / 2 ?playerTwoYPos += 1: playerTwoYPos - 1;
            }
            gc.fillOval(ballXPos, ballYPos, BALL_R, BALL_R);
        } else {
            showTextForGame(gc);
            ballXPos = width / 2;
            ballYPos = height / 2;
            ballXSpeed = new Random().nextInt(2) == 0 ? 1: -1;
            ballYSpeed = new Random().nextInt(2) == 0 ? 1: -1;
        }
        if(ballYPos > height || ballYPos < 0) ballYSpeed *=-1;
        if(ballXPos < playerOneXPos - PLAYER_WIDTH) {
            scoreP2++;
            gameStarted = false;
        }
        if(ballXPos > playerTwoXPos + PLAYER_WIDTH) {
            scoreP1++;
            gameStarted = false;
        }
        if( ((ballXPos + BALL_R > playerTwoXPos) && ballYPos >= playerTwoYPos && ballYPos <= playerTwoYPos + PLAYER_HEIGHT) ||
                ((ballXPos < playerOneXPos + PLAYER_WIDTH) && ballYPos >= playerOneYPos && ballYPos <= playerOneYPos + PLAYER_HEIGHT)) {
            ballYSpeed += 1 * Math.signum(ballYSpeed);
            ballXSpeed += 1 * Math.signum(ballXSpeed);
            ballXSpeed *= -1;
            ballYSpeed *= -1;
        }
        showScore(gc);
        showTwoPlayer(gc);
        showOnePlayer(gc);
    }
    public void showScore(GraphicsContext gc){
        gc.fillText(scoreP1 + "\t\t\t\t\t\t\t\t" + scoreP2, 400, 100);
    }
    public void showOnePlayer(GraphicsContext gc){
        gc.fillRect(playerOneXPos, playerOneYPos, PLAYER_WIDTH, PLAYER_HEIGHT);
    }
    private void showTwoPlayer(GraphicsContext gc){
        gc.fillRect(playerTwoXPos, playerTwoYPos, PLAYER_WIDTH, PLAYER_HEIGHT);
    }
}