While playing the snake game, there were questions that came to my mind. Can you help me?

Hello! I am currently new to java. I am also making a snake game to improve=
 myself. My snake game is working fine now. But I want to improve this snak=
e game. I know I have too many questions. But one of my goals is to improve=
 myself in this field. Naturally, while developing myself, there are questi=
ons that come to my mind. You would make me very happy if you could solve s=
ome or all of these questions. In the meantime, I would be very happy if yo=
u could explain the questions I asked by writing code. In this way, I will =
understand better. Thank you for your immediate attention.

First I want to duplicate the class pages to handle the class issue in my s=
nake game. In other words, I want to take some of the codes in the GamePane=
l in my code and put them in a different class page. For example, I want to=
 create a page called motion and put the parts related to motion in GamePan=
el inside this page. How can I do that?


Secondly, I have now designed the game intro with the help of Swing. And I =
put a button called Start Game at the entrance of the game. Now I want my g=
ame to start when I press this button. But when I run the current trouble p=
rogram, my game entry does not appear. My aim is to make the game entry app=
ear first and then to start the game when I press the button. How can I do =
that?



Third, I want to add sound to the game. How can I do that?



Fourth, I want to have a level part in my game. When the score is 5 my snak=
e will speed up and I want it to write "level 2" to indicate it. When the s=
core is 10, let the snake get even faster and write "level 3". So how do I =
do this? And what part of this code will I place?




My code:

package snake;
public class Main {
    public static void main(String[] args) {
        new GameFrame();
    }
}
//****************************************************


package snake;

import javax.swing.JFrame;

public class GameFrame extends JFrame{
    GameFrame()
    {
        this.add(new GamePanel());
        this.setTitle("Snake Game");
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setResizable(false);
        this.pack();
        this.setVisible(true);
        this.setLocationRelativeTo(null);      =20
    }   =20
}



//******************************************************
package snake;

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

public class GamePanel extends JPanel implements ActionListener {
   =20
    SnakeFoodApple apple =3D new SnakeFoodApple(600, 600, 25);
    static final int SCREEN_WIDTH =3D 600;
    static final int SCREEN_HEIGHT =3D 600;
    static final int GAME_UNITS =3D (SCREEN_WIDTH * SCREEN_HEIGHT) / UNIT_S=
IZE;
    static int DELAY =3D 75;
    final int X[] =3D new int[GAME_UNITS];
    final int Y[] =3D new int[GAME_UNITS];
    int bodyParts =3D 6;
    int applesEaten;
    int appleX;
    int appleY;
    char direction =3D 'R';
    boolean running =3D false;
    Timer timer;
    Random random =3D new Random();


    GamePanel() {
        random =3D new Random();
        this.setPreferredSize(new Dimension(SCREEN_WIDTH, SCREEN_HEIGHT));
        this.setBackground(Color.black);
        this.setFocusable(true);
        this.addKeyListener(new MyKeyAdapter());
        startGame();
    }

    public void startGame() {
        apple.newApple();
        running =3D true;
        timer =3D new Timer(DELAY, this);
        timer.start();
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        draw(g);
    }

    public void draw(Graphics g) {
        if (running) {
            g.setColor(Color.red);
            g.fillOval(apple.getX(), apple.getY(), UNIT_SIZE, UNIT_SIZE);

            for (int i =3D 0; i < bodyParts; i++) {
                if (i =3D=3D 0) {
                    g.setColor(Color.green);
                    g.fillRect(X[i], Y[i], UNIT_SIZE, UNIT_SIZE);
                } else {
                    g.setColor(new Color(random.nextInt(255), random.nextIn=
t(255), random.nextInt(255)));
                    g.fillRect(X[i], Y[i], UNIT_SIZE, UNIT_SIZE);
                }
            }
            g.setColor(Color.red);
            g.setFont(new Font("Ink Free", Font.BOLD, 40));
            FontMetrics metrics =3D getFontMetrics(g.getFont());
            g.drawString("SCORE: " + applesEaten, (SCREEN_WIDTH - metrics.s=
tringWidth("SCORE: " + applesEaten)) / 2, g.getFont().getSize());
        } else {
            gameOver(g);
        }

    }


    public void move() {
        for (int i =3D bodyParts; i > 0; i--) {
            X[i] =3D X[i - 1];
            Y[i] =3D Y[i - 1];
        }
        switch (direction) {
            case 'U':
                Y[0] =3D Y[0] - UNIT_SIZE;
                break;
            case 'D':
                Y[0] =3D Y[0] + UNIT_SIZE;
                break;
            case 'L':
                X[0] =3D X[0] - UNIT_SIZE;
                break;
            case 'R':
                X[0] =3D X[0] + UNIT_SIZE;
                break;
        }
    }

    public void checkApple() {
        if ((X[0] =3D=3D apple.getX()) && (Y[0] =3D=3D apple.getY())) {
            bodyParts++;
            applesEaten++;
            apple.newApple();
        }
    }

    public void checkCollisions() {
        for (int i =3D bodyParts; i > 0; i--) {
            if ((X[0] =3D=3D X[i]) && (Y[0] =3D=3D Y[i])) {
                running =3D false;
            }
        }
     =20
        if (X[0] < 0) {
            running =3D false;
        }
        if (X[0] > SCREEN_WIDTH) {
            running =3D false;
        }
       =20
        if (Y[0] < 0) {
            running =3D false;
        }
        if (Y[0] > SCREEN_HEIGHT) {
            running =3D false;
        }
        if (!running) {
            timer.stop();
        }
    }
   =20
    public void gameOver(Graphics g) {
        g.setColor(Color.red);
        g.setFont(new Font("Ink Free", Font.BOLD, 40));
        FontMetrics metrics1 =3D getFontMetrics(g.getFont());
        g.drawString("SCORE: " + applesEaten, (SCREEN_WIDTH - metrics1.stri=
ngWidth("SCORE: " + applesEaten)) / 2, g.getFont().getSize());
        g.setColor(Color.red);
        g.setFont(new Font("Ink Free", Font.BOLD, 75));
        FontMetrics metrics2 =3D getFontMetrics(g.getFont());
        g.drawString("GAME OVER", (SCREEN_WIDTH - metrics2.stringWidth("GAM=
E OVER")) / 2, SCREEN_HEIGHT / 2);

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (running) {
            move();
            checkApple();
            checkCollisions();
        }
        repaint();  =20
    }

    public class MyKeyAdapter extends KeyAdapter {

        @Override
        public void keyPressed(KeyEvent e) {
            switch (e.getKeyCode()) {
                case KeyEvent.VK_LEFT:
                    if (direction !=3D 'R') {
                        direction =3D 'L';
                    }
                    break;
                case KeyEvent.VK_RIGHT:
                    if (direction !=3D 'L') {
                        direction =3D 'R';
                    }
                    break;
                case KeyEvent.VK_UP:
                    if (direction !=3D 'D') {
                        direction =3D 'U';
                    }
                    break;
                case KeyEvent.VK_DOWN:
                    if (direction !=3D 'U') {
                        direction =3D 'D';
                    }
                    break;

            }
        }
    }
}





//***************************
package snake;

import java.util.Random;

public class SnakeFoodApple {
    private final int screenWidth;
    private final int screenHeight;
    private final int unitSize;
    private final Random random =3D new Random();
    private int appleX;
    private int appleY;

    public SnakeFoodApple(int screenWidth, int screenHeight, int unitSize) =
{
        this.screenWidth =3D screenWidth;
        this.screenHeight =3D screenHeight;
        this.unitSize =3D unitSize;
    }

    public void newApple() {
        appleX =3D random.nextInt(screenWidth / unitSize) * unitSize;
        appleY =3D random.nextInt(screenHeight / unitSize) * unitSize;
    }

    public int getX() {
        return appleX;
    }

    public int getY() {
        return appleY;
    }
    =20
}







//************************************************

package snake;

public class Home extends javax.swing.JFrame {

    public Home() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate=3D"collapsed" desc=3D"Generated Code">    =
                     =20
    private void initComponents() {

        jPanel1 =3D new javax.swing.JPanel();
        jPanel4 =3D new javax.swing.JPanel();
        jLabel2 =3D new javax.swing.JLabel();
        b_start_game =3D new javax.swing.JButton();
        jLabel3 =3D new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE)=
;
        setTitle("Snake Game");
        setResizable(false);

        jPanel1.setBackground(new java.awt.Color(255, 255, 255));
        jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new ja=
va.awt.Color(255, 0, 0), 4));

        jPanel4.setBackground(new java.awt.Color(51, 255, 51));

        jLabel2.setFont(new java.awt.Font("Tahoma", 1, 44)); // NOI18N
        jLabel2.setText("SNAKE GAME");

        b_start_game.setBackground(new java.awt.Color(0, 51, 255));
        b_start_game.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
        b_start_game.setForeground(new java.awt.Color(255, 255, 255));
        b_start_game.setText("START GAME");
        b_start_game.addActionListener(new java.awt.event.ActionListener() =
{
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                b_start_gameActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel4Layout =3D new javax.swing.GroupLayo=
ut(jPanel4);
        jPanel4.setLayout(jPanel4Layout);
        jPanel4Layout.setHorizontalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Align=
ment.LEADING)
            .addGroup(jPanel4Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(b_start_game, javax.swing.GroupLayout.DEFAULT=
_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(jPanel4Layout.createSequentialGroup()
                .addGap(21, 21, 21)
                .addComponent(jLabel2)
                .addContainerGap(24, Short.MAX_VALUE))
        );
        jPanel4Layout.setVerticalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Align=
ment.LEADING)
            .addGroup(jPanel4Layout.createSequentialGroup()
                .addGap(117, 117, 117)
                .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SI=
ZE, 114, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(71, 71, 71)
                .addComponent(b_start_game, javax.swing.GroupLayout.PREFERR=
ED_SIZE, 88, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Shor=
t.MAX_VALUE))
        );

        jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/=
snake/snake.png"))); // NOI18N
        jLabel3.setText("jLabel3");

        javax.swing.GroupLayout jPanel1Layout =3D new javax.swing.GroupLayo=
ut(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Align=
ment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SI=
ZE, 281, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement=
.UNRELATED)
                .addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE=
, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Align=
ment.LEADING)
            .addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE, ja=
vax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addGap(77, 77, 77)
                .addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SI=
ZE, 438, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(77, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout =3D new javax.swing.GroupLayout(getC=
ontentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LE=
ADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.Alignment.TRAILI=
NG, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_S=
IZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LE=
ADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, ja=
vax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                       =20

    private void b_start_gameActionPerformed(java.awt.event.ActionEvent evt=
) {                                            =20

    }                                           =20


    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Home().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                    =20
    private javax.swing.JButton b_start_game;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel4;
    // End of variables declaration                  =20
}