Snake Game in Java: A Beginner's Guide

// Press Shift twice to open the Search Everywhere dialog and type 'show whitespaces', // then press Enter. You can now see whitespace characters in your code. package com.firefor01;

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

public class test extends JFrame implements ActionListener { String name; JButton jbn = new JButton('开始'); D jpn = new D();

test() { Container cn = getContentPane(); cn.setLayout(new BorderLayout()); cn.add(jbn, BorderLayout.NORTH); cn.add(jpn, BorderLayout.CENTER); jbn.addActionListener(this); setSize(600, 400); setVisible(true); }

public void actionPerformed(ActionEvent e) {
    Thread t1 = new Thread(jpn);
    t1.start();
    jpn.requestFocus(true);
}

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

}

class D extends JPanel implements Runnable, KeyListener { int x = 10; int direction = 0; Random r = new Random(); Vector v = new Vector(); Point food = new Point();

D() {
    v.add(new Point(20, 10));
    v.add(new Point(20, 10));
    v.add(new Point(20, 10));
    v.add(new Point(20, 10));

    int t = r.nextInt(20);
    food.x = t * 10;
    food.y = t * 10;
    addKeyListener(this);
}

public void paint(Graphics g) {
    super.paint(g);
    for (int i = 0; i < v.size(); i++) {
        Point p = v.get(i);
        int x = p.x;
        int y = p.y;
        if (i == v.size() - 1) {
            g.setColor(Color.blue);
            g.fillOval(x, y, 9, 9);
        } else {
            g.setColor(Color.black);
            g.fillOval(x, y, 9, 9);
        }
    }

    int x = food.x;
    int y = food.y;
    g.setColor(Color.red);
    g.fillRect(x, y, 9, 9);
}

public void keyPressed(KeyEvent e) {
    if (e.getKeyCode() == KeyEvent.VK_UP && direction != 3) { // Add boundary check
        direction = 2;
    }
    if (e.getKeyCode() == KeyEvent.VK_DOWN && direction != 2) { // Add boundary check
        direction = 3;
    }
    if (e.getKeyCode() == KeyEvent.VK_LEFT && direction != 0) { // Add boundary check
        direction = 1;
    }
    if (e.getKeyCode() == KeyEvent.VK_RIGHT && direction != 1) { // Add boundary check
        direction = 0;
    }
}

public void keyReleased(KeyEvent e) {

}

public void keyTyped(KeyEvent e) {

}

public void run() {
    try {
        while (true) {
            Point head = v.get(v.size() - 1); // Get the head of the snake
            Point newHead = new Point(head); // Create a new head point

            // Update the new head point based on the direction
            if (direction == 0) {
                newHead.x += 10;
            }
            if (direction == 1) {
                newHead.x -= 10;
            }
            if (direction == 2) {
                newHead.y -= 10;
            }
            if (direction == 3) {
                newHead.y += 10;
            }

            // Check if the new head point is hitting the boundary
            if (newHead.x < 0 || newHead.x >= getWidth() || newHead.y < 0 || newHead.y >= getHeight()) {
                JOptionPane.showMessageDialog(null, 'Game over!'); // Show game over message
                System.exit(0); // Exit the program
            }

            // Check if the new head point is hitting the body
            for (int i = 0; i < v.size() - 1; i++) {
                Point p = v.get(i);
                if (p.equals(newHead)) {
                    JOptionPane.showMessageDialog(null, 'Game over!'); // Show game over message
                    System.exit(0); // Exit the program
                }
            }

            v.add(newHead); // Add the new head point to the vector

            // Check if the snake is eating the food
            if (newHead.equals(food)) {
                int t = r.nextInt(20);
                food.x = t * 10;
                food.y = t * 10;
            } else {
                v.remove(0); // Remove the tail of the snake
            }

            repaint(); // Repaint the panel
            Thread.sleep(100); // Delay the thread
        }
    } catch (Exception e) {

    }
}

}