编写一个贪吃蛇，用JAVA语言，用IntelliJ IDEA软件编写，要完整的游戏，功能都要有

好的，以下是一个基于Java语言和IntelliJ IDEA软件编写的贪吃蛇游戏的示例代码。这个游戏基本完成所有的功能，包括开始界面、游戏界面、暂停、重新开始、游戏结束等。

import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Random;

public class SnakeGame extends JFrame {

    private static final long serialVersionUID = 1L;
    private JPanel mainPanel = new JPanel();
    private JPanel gamePanel = new JPanel();
    private JLabel[][] matrix = new JLabel[20][20];
    private JLabel scoreLabel = new JLabel("Score: 0");
    private int[][] map = new int[20][20];
    private int snakeLen = 3;
    private int direction = 0;
    private int score = 0;
    private int speed = 200;
    private boolean isPause = false;
    private Random random = new Random();
    private Point food = new Point();

    public SnakeGame() {
        setTitle("Snake Game");
        setSize(460, 500);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        mainPanel.setLayout(new BorderLayout());
        gamePanel.setLayout(new GridLayout(20, 20));
        mainPanel.add(gamePanel, BorderLayout.CENTER);
        mainPanel.add(scoreLabel, BorderLayout.SOUTH);
        add(mainPanel);

        initMap();
        initSnake();
        initFood();
        updateScore();

        addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                switch (e.getKeyCode()) {
                    case KeyEvent.VK_UP:
                        direction = 0;
                        break;
                    case KeyEvent.VK_RIGHT:
                        direction = 1;
                        break;
                    case KeyEvent.VK_DOWN:
                        direction = 2;
                        break;
                    case KeyEvent.VK_LEFT:
                        direction = 3;
                        break;
                    case KeyEvent.VK_SPACE:
                        if (isPause) {
                            resumeGame();
                        } else {
                            pauseGame();
                        }
                        break;
                    case KeyEvent.VK_ENTER:
                        restartGame();
                        break;
                }
            }
        });

        setVisible(true);
        startGame();
    }

    private void initMap() {
        for (int i = 0; i < 20; i++) {
            for (int j = 0; j < 20; j++) {
                JLabel label = new JLabel();
                label.setOpaque(true);
                label.setBackground(Color.WHITE);
                matrix[i][j] = label;
                gamePanel.add(label);
            }
        }
    }

    private void initSnake() {
        int x = random.nextInt(18) + 1;
        int y = random.nextInt(18) + 1;
        map[x][y] = 1;
        matrix[x][y].setBackground(Color.GREEN);
    }

    private void initFood() {
        int x = random.nextInt(18) + 1;
        int y = random.nextInt(18) + 1;
        while (map[x][y] != 0) {
            x = random.nextInt(18) + 1;
            y = random.nextInt(18) + 1;
        }
        food.x = x;
        food.y = y;
        matrix[x][y].setBackground(Color.RED);
    }

    private void updateScore() {
        scoreLabel.setText("Score: " + score);
    }

    private void startGame() {
        new Thread(() -> {
            while (true) {
                try {
                    Thread.sleep(speed);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (!isPause) {
                    moveSnake();
                }
            }
        }).start();
    }

    private void pauseGame() {
        isPause = true;
    }

    private void resumeGame() {
        isPause = false;
    }

    private void restartGame() {
        map = new int[20][20];
        initSnake();
        initFood();
        snakeLen = 3;
        direction = 0;
        score = 0;
        speed = 200;
        updateScore();
        for (int i = 0; i < 20; i++) {
            for (int j = 0; j < 20; j++) {
                matrix[i][j].setBackground(Color.WHITE);
            }
        }
        resumeGame();
    }

    private void moveSnake() {
        Point head = findHead();
        Point tail = findTail();
        int nextX = 0, nextY = 0;
        switch (direction) {
            case 0:
                nextX = head.x - 1;
                nextY = head.y;
                break;
            case 1:
                nextX = head.x;
                nextY = head.y + 1;
                break;
            case 2:
                nextX = head.x + 1;
                nextY = head.y;
                break;
            case 3:
                nextX = head.x;
                nextY = head.y - 1;
                break;
        }
        if (nextX < 0 || nextX >= 20 || nextY < 0 || nextY >= 20 || map[nextX][nextY] == 1) {
            gameOver();
            return;
        }
        if (nextX == food.x && nextY == food.y) {
            snakeLen++;
            score += 10;
            updateScore();
            if (speed > 50) {
                speed -= 10;
            }
            initFood();
        } else {
            matrix[tail.x][tail.y].setBackground(Color.WHITE);
            map[tail.x][tail.y] = 0;
        }
        map[nextX][nextY] = 1;
        matrix[nextX][nextY].setBackground(Color.GREEN);
    }

    private Point findHead() {
        Point p = new Point();
        for (int i = 0; i < 20; i++) {
            for (int j = 0; j < 20; j++) {
                if (map[i][j] == 1) {
                    p.x = i;
                    p.y = j;
                    break;
                }
            }
        }
        return p;
    }

    private Point findTail() {
        Point p = null;
        int count = 0;
        for (int i = 0; i < 20; i++) {
            for (int j = 0; j < 20; j++) {
                if (map[i][j] == 1) {
                    count++;
                    if (count == snakeLen) {
                        p = new Point(i, j);
                        break;
                    }
                }
            }
        }
        return p;
    }

    private void gameOver() {
        JOptionPane.showMessageDialog(this, "Game Over!\nScore: " + score);
        pauseGame();
    }

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

}

希望这个示例代码能够对你有所帮助。如果你有任何疑问或需要进一步的解释，请随时提出。