帮我利用java写一款贪吃蛇游戏

好的，下面是一个简单的贪吃蛇游戏的Java代码，希望能帮到你：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class SnakeGame extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;
    private JPanel gamePanel;
    private JButton startButton;
    private Timer timer;

    private final int WIDTH = 500;
    private final int HEIGHT = 500;

    private final int DOT_SIZE = 10;
    private final int ALL_DOTS = 900;
    private final int RAND_POS = 29;

    private int DELAY = 140;

    private int[] x = new int[ALL_DOTS];
    private int[] y = new int[ALL_DOTS];

    private int dots;
    private int apple_x;
    private int apple_y;

    private boolean leftDirection = false;
    private boolean rightDirection = true;
    private boolean upDirection = false;
    private boolean downDirection = false;
    private boolean inGame = true;

    public SnakeGame() {
        initUI();
    }

    private void initUI() {
        setTitle("Snake Game");
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        gamePanel = new JPanel();
        gamePanel.setBackground(Color.black);
        gamePanel.setPreferredSize(new Dimension(WIDTH, HEIGHT));
        add(gamePanel, BorderLayout.CENTER);

        startButton = new JButton("Start");
        startButton.addActionListener(this);
        add(startButton, BorderLayout.NORTH);

        timer = new Timer(DELAY, this);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private void startGame() {
        dots = 3;
        for (int i = 0; i < dots; i++) {
            x[i] = 50 - i * DOT_SIZE;
            y[i] = 50;
        }

        locateApple();

        timer.start();
    }

    private void locateApple() {
        int r = (int) (Math.random() * RAND_POS);
        apple_x = r * DOT_SIZE;

        r = (int) (Math.random() * RAND_POS);
        apple_y = r * DOT_SIZE;
    }

    private void checkApple() {
        if (x[0] == apple_x && y[0] == apple_y) {
            dots++;
            locateApple();
        }
    }

    private void checkCollision() {
        for (int i = dots; i > 0; i--) {
            if (i > 4 && x[0] == x[i] && y[0] == y[i]) {
                inGame = false;
            }
        }

        if (y[0] >= HEIGHT) {
            inGame = false;
        }

        if (y[0] < 0) {
            inGame = false;
        }

        if (x[0] >= WIDTH) {
            inGame = false;
        }

        if (x[0] < 0) {
            inGame = false;
        }

        if (!inGame) {
            timer.stop();
        }
    }

    private void move() {
        for (int i = dots; i > 0; i--) {
            x[i] = x[i - 1];
            y[i] = y[i - 1];
        }

        if (leftDirection) {
            x[0] -= DOT_SIZE;
        }

        if (rightDirection) {
            x[0] += DOT_SIZE;
        }

        if (upDirection) {
            y[0] -= DOT_SIZE;
        }

        if (downDirection) {
            y[0] += DOT_SIZE;
        }
    }

    private void paint(Graphics g) {
        super.paint(g);

        if (inGame) {
            g.setColor(Color.red);
            g.fillOval(apple_x, apple_y, DOT_SIZE, DOT_SIZE);

            for (int i = 0; i < dots; i++) {
                if (i == 0) {
                    g.setColor(Color.green);
                } else {
                    g.setColor(Color.white);
                }

                g.fillRect(x[i], y[i], DOT_SIZE, DOT_SIZE);
            }

            Toolkit.getDefaultToolkit().sync();

        } else {
            gameOver(g);
        }
    }

    private void gameOver(Graphics g) {
        String msg = "Game Over";
        Font font = new Font("Helvetica", Font.BOLD, 14);
        FontMetrics metr = getFontMetrics(font);

        g.setColor(Color.white);
        g.setFont(font);
        g.drawString(msg, (WIDTH - metr.stringWidth(msg)) / 2, HEIGHT / 2);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (inGame) {
            checkApple();
            checkCollision();
            move();
        }

        repaint();
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            SnakeGame game = new SnakeGame();
            game.setVisible(true);
        });
    }
}

这是一个比较简单的实现，可以根据需要自行修改和完善。