How to restart this java snake game?

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I copied most code from "Bro Code" in youtube since I'm trying to create a similar game of his. I wanted to learn the basics of creating these types of games that relies on a grid. I'm trying to add a reset feature though I am having trouble after hours of attempts. I want to be able to press the 'R' key in order for the game to restart. However, with my current code, it just doesn't work when pressed in the game over screen. It displays a glimpse of the grid and red circle then comes back to the game over screen. If pressed ingame, it just makes the snake go faster.

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_WIDTH = 600;
    static final int SCREEN_HEIGHT = 600;
    static final int UNIT_SIZE = 25;
    static final int GAME_UNITS = (SCREEN_WIDTH*SCREEN_HEIGHT)/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 = 0;
    int appleX;
    int appleY;
    char direction = 'R';
    boolean running = false;
    Timer timer;
    Random random;

    GamePanel() {
        random = 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() {
        newApple();
        running = true;
        timer = new Timer(DELAY,this);
        timer.start();
    }

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

    public void draw(Graphics g) {
        if (running) {
            // optional grid
            for(int i=0; i<SCREEN_HEIGHT/UNIT_SIZE; i++) {
                g.drawLine(i*UNIT_SIZE, 0, i*UNIT_SIZE, SCREEN_HEIGHT);
                g.drawLine(0, i*UNIT_SIZE, SCREEN_WIDTH, i*UNIT_SIZE);
            }
            g.setColor(Color.red);
            g.fillOval(appleX, appleY, UNIT_SIZE, UNIT_SIZE);

            // snek
            for(int i=0; i<bodyParts; i++) {
                if(i==0) {
                    g.setColor(Color.green);
                    g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
                } else {
                    g.setColor(new Color(45,180,0));
                    g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
                }
            }
            // score
            g.setColor(Color.white);
            g.setFont(new Font("Courier New", Font.BOLD, 40));
            FontMetrics metrics = getFontMetrics(g.getFont());
            g.drawString(String.valueOf(applesEaten),(SCREEN_WIDTH - metrics.stringWidth(String.valueOf(applesEaten)))/2,g.getFont().getSize());
        }
        else {
            gameOver(g);
        }
    }

    public void newApple() {
        appleX = random.nextInt((int)(SCREEN_WIDTH/UNIT_SIZE))*UNIT_SIZE;
        appleY = random.nextInt((int)(SCREEN_HEIGHT/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() {
        // checks if head collides with body
        for(int i=bodyParts; i>0; i--) {
            if ((x[0] == x[i]) && (y[0] == y[i])) {
                running = false;
            }
        }
        // checks if head touches left border
        if (x[0] < 0) {
            running = false;
        }
        // checks if head touches right border
        if (x[0] > SCREEN_WIDTH-UNIT_SIZE) {
            running = false;
        }
        // checks if head touches top border
        if (y[0] < 0) {
            running = false;
        }
        // checks if head touches bottom border
        if (y[0] > SCREEN_HEIGHT-UNIT_SIZE) {
            running = false;
        }

        if (!running) {
             timer.stop();
        }

    }

    public void gameOver(Graphics g) {
        // score
        g.setColor(Color.white);
        g.setFont(new Font("Courier New", Font.BOLD, 20));
        FontMetrics metrics1 = getFontMetrics(g.getFont());
        g.drawString("score: " + applesEaten,(SCREEN_WIDTH - metrics1.stringWidth("score: " + applesEaten))/2,g.getFont().getSize());

        // Game Over text
        g.setColor(Color.green);
        g.setFont(new Font("Courier New", Font.PLAIN, 40));
        FontMetrics metrics2 = getFontMetrics(g.getFont());
        g.drawString("game over",(SCREEN_WIDTH - metrics2.stringWidth("game over"))/2,SCREEN_HEIGHT/2);
    }

    public void restartGame() {
        System.out.println("debug");
        applesEaten = 0;
        bodyParts = 6;
        direction = 'R';
        repaint();
        startGame();
    }

    @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_A:
                    if(direction != 'R') {
                        direction = 'L';
                    }
                    break;
                case KeyEvent.VK_D:
                    if(direction != 'L') {
                        direction = 'R';
                    }
                    break;
                case KeyEvent.VK_W:
                    if(direction != 'D') {
                        direction = 'U';
                    }
                    break;
                case KeyEvent.VK_S:
                    if(direction != 'U') {
                        direction = 'D';
                    }
                    break;
            }
            if (e.getKeyCode() == KeyEvent.VK_R) {
                restartGame();
            }
        }
    }

}
java
1 Answers

I also could find a way to do that as he wrote the code in such a way that we would play the game only once. I would have needed to change a lot of variables and other things, so instead, I found a solution for it. You can just hide the current frame when you call a restart and show another new one. Your restartGame code will be:

public void restartGame() {
   setVisible(false);
   new GameFrame();
}

and the entire could be:

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_WIDTH = 600;
    static final int SCREEN_HEIGHT = 600;
    static final int UNIT_SIZE = 25;
    static final int GAME_UNITS = (SCREEN_WIDTH*SCREEN_HEIGHT)/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 = 0;
    int appleX;
    int appleY;
    char direction = 'R';
    boolean running = false;
    Timer timer;
    Random random;

    GamePanel() {
        random = 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() {
        newApple();
        running = true;
        timer = new Timer(DELAY,this);
        timer.start();
    }

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

    public void draw(Graphics g) {
        if (running) {
            // optional grid
            for(int i=0; i<SCREEN_HEIGHT/UNIT_SIZE; i++) {
                g.drawLine(i*UNIT_SIZE, 0, i*UNIT_SIZE, SCREEN_HEIGHT);
                g.drawLine(0, i*UNIT_SIZE, SCREEN_WIDTH, i*UNIT_SIZE);
            }
            g.setColor(Color.red);
            g.fillOval(appleX, appleY, UNIT_SIZE, UNIT_SIZE);

            // snek
            for(int i=0; i<bodyParts; i++) {
                if(i==0) {
                    g.setColor(Color.green);
                    g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
                } else {
                    g.setColor(new Color(45,180,0));
                    g.fillRect(x[i], y[i], UNIT_SIZE, UNIT_SIZE);
                }
            }
            // score
            g.setColor(Color.white);
            g.setFont(new Font("Courier New", Font.BOLD, 40));
            FontMetrics metrics = getFontMetrics(g.getFont());
            g.drawString(String.valueOf(applesEaten),(SCREEN_WIDTH - metrics.stringWidth(String.valueOf(applesEaten)))/2,g.getFont().getSize());
        }
        else {
            gameOver(g);
        }
    }

    public void newApple() {
        appleX = random.nextInt((int)(SCREEN_WIDTH/UNIT_SIZE))*UNIT_SIZE;
        appleY = random.nextInt((int)(SCREEN_HEIGHT/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() {
        // checks if head collides with body
        for(int i=bodyParts; i>0; i--) {
            if ((x[0] == x[i]) && (y[0] == y[i])) {
                running = false;
            }
        }
        // checks if head touches left border
        if (x[0] < 0) {
            running = false;
        }
        // checks if head touches right border
        if (x[0] > SCREEN_WIDTH-UNIT_SIZE) {
            running = false;
        }
        // checks if head touches top border
        if (y[0] < 0) {
            running = false;
        }
        // checks if head touches bottom border
        if (y[0] > SCREEN_HEIGHT-UNIT_SIZE) {
            running = false;
        }

        if (!running) {
             timer.stop();
        }

    }

    public void gameOver(Graphics g) {
        g.setColor(Color.white);
        g.setFont(new Font("Courier New", Font.BOLD, 20));
        FontMetrics metrics1 = getFontMetrics(g.getFont());
        g.drawString("score: " + applesEaten,(SCREEN_WIDTH - metrics1.stringWidth("score: " + applesEaten))/2,g.getFont().getSize());

        // Game Over text
        g.setColor(Color.green);
        g.setFont(new Font("Courier New", Font.PLAIN, 40));
        FontMetrics metrics2 = getFontMetrics(g.getFont());
        g.drawString("Game over",(SCREEN_WIDTH - metrics2.stringWidth("Game Over"))/2,SCREEN_HEIGHT/2);
        g.setFont(new Font("Courier New", Font.PLAIN, 20));
        FontMetrics metrics3 = getFontMetrics(g.getFont());
        g.drawString("Press 'R' to play again",(SCREEN_WIDTH - metrics3.stringWidth("Press 'R' to play again"))/2,SCREEN_HEIGHT/2 + 70);
    }

    public void restartGame() {
        setVisible(false);
        new GameFrame();
    }

    public void dispose() {
        JFrame parent = (JFrame) this.getTopLevelAncestor();
        parent.dispose();
    }

    @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;
                case KeyEvent.VK_R:
                    restartGame();
                    System.out.println("restart");
                    break;
            }
        }
    }

}

I have also added a few more things which you can see in the testing below:

enter image description here

user_171332830
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