snake-game

this is snake game
package com.zetcode;

import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Graphics; import java.awt.Image; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.ImageIcon; import javax.swing.JPanel; import javax.swing.Timer;

public class Board extends JPanel implements ActionListener {

private final int B_WIDTH = 300;
private final int B_HEIGHT = 300;
private final int DOT_SIZE = 10;
private final int ALL_DOTS = 900;
private final int RAND_POS = 29;
private final int DELAY = 140;

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

private Timer timer;
private Image ball;
private Image apple;
private Image head;

public Board() {
    
    initBoard();
}

private void initBoard() {

    addKeyListener(new TAdapter());
    setBackground(Color.black);
    setFocusable(true);

    setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
    loadImages();
    initGame();
}

private void loadImages() {

    ImageIcon iid = new ImageIcon("src/resources/dot.png");
    ball = iid.getImage();

    ImageIcon iia = new ImageIcon("src/resources/apple.png");
    apple = iia.getImage();

    ImageIcon iih = new ImageIcon("src/resources/head.png");
    head = iih.getImage();
}

private void initGame() {

    dots = 3;

    for (int z = 0; z < dots; z++) {
        x[z] = 50 - z * 10;
        y[z] = 50;
    }
    
    locateApple();

    timer = new Timer(DELAY, this);
    timer.start();
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);

    doDrawing(g);
}

private void doDrawing(Graphics g) {
    
    if (inGame) {

        g.drawImage(apple, apple_x, apple_y, this);

        for (int z = 0; z < dots; z++) {
            if (z == 0) {
                g.drawImage(head, x[z], y[z], this);
            } else {
                g.drawImage(ball, x[z], y[z], this);
            }
        }

        Toolkit.getDefaultToolkit().sync();

    } else {

        gameOver(g);
    }        
}

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

    g.setColor(Color.white);
    g.setFont(small);
    g.drawString(msg, (B_WIDTH - metr.stringWidth(msg)) / 2, B_HEIGHT / 2);
}

private void checkApple() {

    if ((x[0] == apple_x) && (y[0] == apple_y)) {

        dots++;
        locateApple();
    }
}

private void move() {

    for (int z = dots; z > 0; z--) {
        x[z] = x[(z - 1)];
        y[z] = y[(z - 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 checkCollision() {

    for (int z = dots; z > 0; z--) {

        if ((z > 4) && (x[0] == x[z]) && (y[0] == y[z])) {
            inGame = false;
        }
    }

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

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

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

    if (x[0] < 0) {
        inGame = false;
    }
    
    if (!inGame) {
        timer.stop();
    }
}

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));
}

@Override
public void actionPerformed(ActionEvent e) {

    if (inGame) {

        checkApple();
        checkCollision();
        move();
    }

    repaint();
}

private class TAdapter extends KeyAdapter {

    @Override
    public void keyPressed(KeyEvent e) {

        int key = e.getKeyCode();

        if ((key == KeyEvent.VK_LEFT) && (!rightDirection)) {
            leftDirection = true;
            upDirection = false;
            downDirection = false;
        }

        if ((key == KeyEvent.VK_RIGHT) && (!leftDirection)) {
            rightDirection = true;
            upDirection = false;
            downDirection = false;
        }

        if ((key == KeyEvent.VK_UP) && (!downDirection)) {
            upDirection = true;
            rightDirection = false;
            leftDirection = false;
        }

        if ((key == KeyEvent.VK_DOWN) && (!upDirection)) {
            downDirection = true;
            rightDirection = false;
            leftDirection = false;
        }
    }
}

}