Why i can't close my JFrame with the .dispose() method

Question

Im trying to "Restart" my little snake game by pressing "Enter". It works but it opens a new JFrame and leaves the old one opened. And if i play the game 4 times i will have 4 opened windows at the end. I know this might sound as a stupid question, but im introducing myself in the gui world and any kind of help would be appreciated. Thank you guys: Here i leave the 3 classes that run my program:

public class SnakeGame { //main class

    public static void main(String[] args) {
        GameFrame frame = new GameFrame();
    }
    
}

    import javax.swing.JFrame;


public class GameFrame extends JFrame{
    
    GamePanel panel;
   
    
    GameFrame(){
        
         panel = new GamePanel();
        
        this.add(panel);
        this.setTitle("Snake");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setResizable(false);
        this.pack();
        this.setVisible(true);
        this.setLocationRelativeTo(null); //centra el JFrame en la pantalla
    }
}

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

public class GamePanel extends JPanel implements ActionListener {
    

    static final int SCREEN_ANCHO = 600;
    static final int SCREEN_ALTO = 600;
    static final int UNIT_SIZE = 25;
    static final int GAME_UNITS = ((SCREEN_ANCHO * SCREEN_ALTO) / UNIT_SIZE);
    static final int DELAY = 75;

    final int[] x = new int[GAME_UNITS];
    final int[] y = new int[GAME_UNITS];

    int bodyParts = 6;
    int applesEaten;
    int appleX;
    int appleY;
    char direction = 'R';
    boolean running = false;
    Timer timer;   // crea un objeto de tipo timer que sirve para iniciar acciones cada x tiempo
    Random random; // objeto de tipo random para generar numeros (posiciones) aleatorias
    
    

    GamePanel() {

        random = new Random();
        this.setPreferredSize(new Dimension(SCREEN_ANCHO, SCREEN_ALTO));
        this.setBackground(Color.BLACK);
        this.setFocusable(true); //hace que que los eventos incidan sobre el panel (hace que sea posible ponerle el foco)
        this.addKeyListener(new MyKeyAdapter());
        startGame();
        
        

    }

    public void startGame() {
        newApple();
        running = true;
        timer = new Timer(DELAY, this); //contador que actua cada x tiempo sobre el objeto indicado (el panel si pones this)
        timer.start(); //comienza el contador

    }

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

    public void draw(Graphics g) {
        if(running){
//        for (int i = 0; i < SCREEN_ALTO / UNIT_SIZE; i++) {
//            g.drawLine(i * UNIT_SIZE, 0, i * UNIT_SIZE, SCREEN_ALTO);
//            g.drawLine(0, i * UNIT_SIZE, SCREEN_ANCHO, i * UNIT_SIZE);
//        }
        g.setColor(Color.RED);
        g.fillOval(appleX, appleY, UNIT_SIZE, UNIT_SIZE);

        for (int i = 0; i < bodyParts; i++) {
            if (i == 0) {
                g.setColor(Color.green.darker().darker());
                g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
            } else {
                g.setColor(Color.green.brighter());
                g.setColor(new Color(random.nextInt(255), random.nextInt(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, 35));
        FontMetrics metrics = getFontMetrics(g.getFont());
        g.drawString("Score:" + applesEaten, (SCREEN_ANCHO - metrics.stringWidth("Score:" + applesEaten))/2, g.getFont().getSize());

        }
        }
        else{
            gameOver(g);
        }

    }

    public void newApple() {

        appleX = random.nextInt((int) (SCREEN_ANCHO / UNIT_SIZE)) * UNIT_SIZE;
        appleY = random.nextInt((int) (SCREEN_ALTO / UNIT_SIZE)) * UNIT_SIZE;

    }

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

        switch (direction) {
            case 'U':
                y[0] = y[0] - UNIT_SIZE;
                break;
            case 'D':
                y[0] = y[0] + UNIT_SIZE;
                break;
            case 'L':
                x[0] = x[0] - UNIT_SIZE;
                break;
            case 'R':
                x[0] = x[0] + UNIT_SIZE;
                break;
        }

    }

    public void checkApple() {

        if ((x[0] == appleX) && (y[0] == appleY)) {
            bodyParts++;
            applesEaten++;
            newApple();
        }

    }

    public void checkCollisions() {
        //revisa si la cabeza se choca con el cuerpo
        for (int i = bodyParts; i > 0; i--) {
            if ((x[0] == x[i]) && (y[0] == y[i])) {
                running = false;
            }
        }
        //revisa si la cabeza toca borde izquierdo
        if (x[0] < 0) {
            x[0] = SCREEN_ANCHO-Math.abs(x[0]);
        }
        //revisa si la cabeza toca borde derecho
        if (x[0] >= SCREEN_ANCHO) {
            x[0] = x[0]%SCREEN_ANCHO;
        }
        //revisa si la cabeza toca borde superior
        if (y[0] < 0) {
            y[0]=SCREEN_ALTO-Math.abs(y[0]);
        }
        //revisa si la cabeza toca borde inferior
        if (y[0] >= SCREEN_ALTO) {
            y[0]=y[0]%SCREEN_ALTO;
        }
        
        
        

    }
    
    

    public void gameOver(Graphics g) {
        //GameOver text
        g.setColor(Color.RED);
        g.setFont(new Font("Ink Free", Font.BOLD, 75));
        FontMetrics metrics = getFontMetrics(g.getFont());
        g.drawString("GAME OVER", (SCREEN_ANCHO - metrics.stringWidth("GAME OVER"))/2, SCREEN_ALTO/2-20);
        
        //score
        g.setFont(new Font("Ink Free", Font.BOLD, 55));
        metrics = getFontMetrics(g.getFont());
        g.drawString("Score:" + applesEaten, (SCREEN_ANCHO - metrics.stringWidth("Score:" + applesEaten))/2, SCREEN_ALTO/2+40);
        
        //PLAY AGAIN
        g.setFont(new Font("Ink Free", Font.BOLD, 35));
        metrics = getFontMetrics(g.getFont());
        g.drawString("Press ENTER to play again", (SCREEN_ANCHO - metrics.stringWidth("Press ENTER to playa again"))/2, SCREEN_ALTO/2+80);
       
        
        
        
        
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        if (running) {
            move();
            checkApple();
            checkCollisions();
        }
        repaint();
        
        
            
    }

    public class MyKeyAdapter extends KeyAdapter {

        @Override
        public void keyPressed(KeyEvent e) {
            switch (e.getKeyCode()) {
                case KeyEvent.VK_LEFT:
                    if (direction != 'R') {
                        direction = 'L';
                    }
                    break;
                case KeyEvent.VK_RIGHT:
                    if (direction != 'L') {
                        direction = 'R';
                    }
                    break;
                case KeyEvent.VK_UP:
                    if (direction != 'D') {
                        direction = 'U';
                    }
                    break;
                case KeyEvent.VK_DOWN:
                    if (direction != 'U') {
                        direction = 'D';
                    }
                    break;
            }
            if(e.getKeyCode() == KeyEvent.VK_SPACE){ //this is were i tried to close the old window
                new GameFrame();
            }

        }

    }
    
    
        
    }

Answer 1

I've seen that code from Bro Code's video and I had the same problem before. I did fix it though but with a different approach, I added a new button and whenever I click the button the game resets for me, here is the code:

Button Code:

        resetButton = new JButton();
        resetButton.setText("Click to restart the Game!");
        resetButton.setFont(F1);
        resetButton.setForeground(Color.WHITE);
        resetButton.setBackground(Color.BLACK);
        resetButton.setSize(100, 50);
        resetButton.setLocation(0, 200);
        resetButton.addActionListener(this);
        
        this.add(resetButton, BorderLayout.PAGE_END);

And here is the code for button:

public void actionPerformed(ActionEvent e) {
        if(e.getSource() == resetButton) {
            this.remove(panel); // Closes the Game
            panel = new GamePanel(); // Makes a new a Game
            this.add(panel); // Opens the game
            SwingUtilities.updateComponentTreeUI(this); // Automatically updates the game frame
            panel.requestFocusInWindow(); // Brings back focus to the game from the reset button
            
        }
        
    }

Add these to the GameFrame class and it should work.