请用Java写一个贪吃蛇游戏

以下是一个简单的贪吃蛇游戏的Java代码示例：

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class SnakeGame extends JFrame implements KeyListener {

    private final int WIDTH = 800;
    private final int HEIGHT = 600;
    private final int DOT_SIZE = 20;
    private final int ALL_DOTS = (WIDTH * HEIGHT) / (DOT_SIZE * DOT_SIZE);
    private final int RAND_POS = 30;
    private final int DELAY = 140;
    
    private List<Point> snake;
    private Point apple;
    private boolean inGame;
    private Timer timer;
    private int direction;

    public SnakeGame() {
        setTitle("Snake Game");
        setSize(WIDTH, HEIGHT);
        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
        addKeyListener(this);

        snake = new ArrayList<>();
        inGame = true;
        direction = KeyEvent.VK_RIGHT;
        timer = new Timer(DELAY, e -> gameLoop());

        initGame();
    }

    private void initGame() {
        snake.clear();
        snake.add(new Point(100, 100));
        snake.add(new Point(80, 100));
        snake.add(new Point(60, 100));
        generateApple();
        timer.start();
    }

    private void generateApple() {
        Random random = new Random();
        int x = random.nextInt(RAND_POS) * DOT_SIZE;
        int y = random.nextInt(RAND_POS) * DOT_SIZE;
        apple = new Point(x, y);
    }

    private void gameLoop() {
        if (inGame) {
            move();
            checkCollision();
            repaint();
        }
    }

    private void move() {
        Point head = new Point(snake.get(0));
        if (direction == KeyEvent.VK_RIGHT) {
            head.x += DOT_SIZE;
        } else if (direction == KeyEvent.VK_LEFT) {
            head.x -= DOT_SIZE;
        } else if (direction == KeyEvent.VK_UP) {
            head.y -= DOT_SIZE;
        } else if (direction == KeyEvent.VK_DOWN) {
            head.y += DOT_SIZE;
        }
        snake.add(0, head);
        snake.remove(snake.size() - 1);
    }

    private void checkCollision() {
        Point head = snake.get(0);
        if (head.x >= WIDTH || head.x < 0 || head.y >= HEIGHT || head.y < 0) {
            inGame = false;
        }
        for (int i = 1; i < snake.size(); i++) {
            if (head.equals(snake.get(i))) {
                inGame = false;
                break;
            }
        }
        if (head.equals(apple)) {
            snake.add(new Point(-1, -1));
            generateApple();
        }
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if (inGame) {
            g.setColor(Color.RED);
            g.fillRect(apple.x, apple.y, DOT_SIZE, DOT_SIZE);

            g.setColor(Color.GREEN);
            for (Point point : snake) {
                g.fillRect(point.x, point.y, DOT_SIZE, DOT_SIZE);
            }
        } else {
            g.setColor(Color.RED);
            g.setFont(new Font("Arial", Font.BOLD, 40));
            g.drawString("Game Over", WIDTH / 2 - 120, HEIGHT / 2);
        }
    }

    @Override
    public void keyTyped(KeyEvent e) {
    }

    @Override
    public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();
        if (key == KeyEvent.VK_LEFT && direction != KeyEvent.VK_RIGHT) {
            direction = KeyEvent.VK_LEFT;
        } else if (key == KeyEvent.VK_RIGHT && direction != KeyEvent.VK_LEFT) {
            direction = KeyEvent.VK_RIGHT;
        } else if (key == KeyEvent.VK_UP && direction != KeyEvent.VK_DOWN) {
            direction = KeyEvent.VK_UP;
        } else if (key == KeyEvent.VK_DOWN && direction != KeyEvent.VK_UP) {
            direction = KeyEvent.VK_DOWN;
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
    }

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

这个代码创建了一个继承自JFrame的SnakeGame类，实现了一个简单的贪吃蛇游戏。在游戏中，玩家控制蛇移动，吃掉苹果来得分，如果蛇撞墙或撞到自己，则游戏结束