Restarting a Java Game

Question

I have a Java Game i need to restart it when the user presses the restart button. My code snippets :

package projectflappy;
//imports
 public class TheGame extends JFrame  implements MouseListener{
 JPanel jp;
 //declaration of the varibles
   ....
 int x_ball = 30;
int y_ball = 200;
int x_width = 500;
int y_height = 500;
Label img = new Label();
int count = 5 , test = -4000;
int i; //for ball loop
Ellipse2D Ball;
int cord_xup1 = 175,cord_xdown1 = 175;
int cord_xup2 = 320,cord_xdown2 = 320;
int cord_xup3 = 460,cord_xdown3 = 460;
int cord_xup4 = 585,cord_xdown4 = 585;
int cord_xup5 = 700,cord_xdown5 = 700;
Boolean flag = true;
RoundRectangle2D up1,down1,up2,down2,up3,down3,up4,down4,up5,down5;
Font font = new Font("Matura MT Script Capitals",Font.ROMAN_BASELINE,40);
Font font1 = new Font("Matura MT Script Capitals",Font.ROMAN_BASELINE,20);
Font font3 = new Font("Matura MT Script Capitals",Font.ROMAN_BASELINE,20);
Font font4 = new Font("Matura MT Script Capitals",Font.ROMAN_BASELINE,10);
float das[] = {10.0f};
BasicStroke color = new   BasicStroke(10,BasicStroke.CAP_ROUND,BasicStroke.JOIN_BEVEL,20.0f,das,0.0f); 


private CellRendererPane crp = new CellRendererPane(); 

GradientPaint gp2 = new GradientPaint(20, 0, 
Color.DARK_GRAY, 0, 10, Color.GRAY, true);


    GradientPaint gp3 = new GradientPaint(30, 0, 
    Color.BLACK, 0, 20, Color.GREEN, true);

   Toolkit kit = Toolkit.getDefaultToolkit();

   //Getting the "background.jpg" image we have in the folder
      Image background = kit.getImage("D:\\College\\Programs\\ProjectFLAPPY\\src\\projectflappy\\1.png");

   JLabel a = new JLabel("Get Ready ! Click to Start.");
   JLabel retry = new JLabel(new          
  ImageIcon("D:\\College\\Programs\\ProjectFLAPPY\\src\\projectflappy\\unnamed.png"));
//constructor
public TheGame() throws IOException 
{
    super("Simple Drawing");
    setSize(x_width, y_height);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);

    jp = new DrawingPanel();
    add(jp);

    addMouseListener(this);


}
// Timer class initiazation--animating the ball

ActionListener action = new ActionListener() {

    @Override
    public void actionPerformed(ActionEvent ae) {
       update();

       repaint();
    }
};
Timer t = new Timer(50,action);

public void mouseClicked(MouseEvent e) {
     // mouse events for animating 
}

// for drawing on the panel
class DrawingPanel extends JPanel{
    private static final long serialVersionUID = 1L;

    public DrawingPanel() {
        setPreferredSize(new Dimension(300, 300));
        setLayout(null);
        retry.setVisible(false);
        retry.setBounds(175,260,46,46);
        a.setForeground(Color.YELLOW);
        a.setFont(font1);
        a.setVisible(true);
        a.setBounds(105,200,300,100);
        add(a);
        add(retry);

    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D d = (Graphics2D)g;
        d.drawImage(background, -270,-30, this);
        Ball = new Ellipse2D.Double(x_ball,y_ball,30,30);

        d.setColor(Color.green);
        d.setFont(font3);


        up1 = new RoundRectangle2D.Double(cord_xup1,-5,30,175,20,20);
        down1 = new RoundRectangle2D.Double(cord_xdown1,310,30,155,20,20);

        up2 = new RoundRectangle2D.Double(cord_xup2,-5,30,200,20,20);
        down2 = new RoundRectangle2D.Double(cord_xdown2,310,30,175,20,20);

        up3 = new RoundRectangle2D.Double(cord_xup3,-5,30,230,20,20);
        down3 = new RoundRectangle2D.Double(cord_xdown3,350,30,135,20,20);

        up4 = new RoundRectangle2D.Double(cord_xup4,-5,30,115,20,20);
        down4 = new RoundRectangle2D.Double(cord_xdown4,240,30,115,20,20);

        d.setPaint(gp2);
        d.setStroke(color);
        d.fill(up1);
        d.fill(down1);

        d.fill(up2);
        d.fill(down2);

        d.fill(up3);
        d.fill(down3);

        d.fill(up4);
        d.fill(down4);


        d.setPaint(gp3);
        d.setStroke(color);
        d.fill(Ball);
        d.setColor(Color.BLACK);
        d.setFont(font1);
        d.drawString(""+score ,200,50);
        if( Ball.intersects(up1.getBounds()) || Ball.intersects(down1.getBounds()) || Ball.intersects(up2.getBounds()) || Ball.intersects(down2.getBounds()) || Ball.intersects(up3.getBounds()) || Ball.intersects(down3.getBounds()) || Ball.intersects(up4.getBounds()) || Ball.intersects(down4.getBounds()))
    {
        t.stop();
        flag = false;
        d.setColor(Color.red);
        d.setFont(font);
        d.drawString("Game Over : "+score ,100,250);
        retry.setVisible(true);
    }
        ****this is the retry button actually it is a JLabel i have used a mouse event over it
        retry.addMouseListener( new MouseListener(){
         @Override
            public void mouseClicked(MouseEvent e) {
                ***i have tried this but doesnt work.
                new DrawingPanel();
                t.restart();
            }

            @Override
            public void mousePressed(MouseEvent e) {
               // throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

            @Override
            public void mouseEntered(MouseEvent e) {
                //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }

            @Override
            public void mouseExited(MouseEvent e) {
                //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
            }
});
    }

}   


public void update()
{
    cord_xdown1 -= 5;
    cord_xup1 -= 5;

    cord_xdown2 -= 5;
    cord_xup2 -= 5;

    cord_xdown3 -= 5;
    cord_xup3 -= 5;

    cord_xdown4 -= 5;
    cord_xup4 -= 5;

    cord_xdown5 -= 5;
    cord_xup5 -= 5;

    if( cord_xup1 <=-20)
    {
        cord_xup1 = 500;
        cord_xdown1 = 500;
    }
    if( cord_xup2 <=-20)
    {
        cord_xup2 = 500;
        cord_xdown2 = 500;
    }
    if( cord_xup3 <=-20)
    {
        cord_xup3 = 500;
        cord_xdown3 = 500;
    }
    if( cord_xup4 <=-20)
    {
        cord_xup4 = 500;
        cord_xdown4 = 500;
    }
    if( cord_xup5 <=-20)
    {
        cord_xup5 = 500;
        cord_xdown5 = 500;
    }

    if(count >= 0)
    {
        y_ball = y_ball - 7;
        count--;

        if( y_ball == y_height)
        {
            t.stop();
        }
    }
    else
    {
        y_ball = y_ball + 7;
        if( y_ball == y_height-70)
        {
            t.stop();
        }
    }

    if(cord_xdown1 == x_ball || cord_xdown2 == x_ball || cord_xdown3 == x_ball || cord_xdown4  == x_ball)
        {   
            score = score+1;

        }

}
 public static void main(String[] args) throws IOException {
    new TheGame();

}

}

I have tried something but it doesn't work. Give me some idea on how to work on this. And when I try to do something like this

  new TheGame();

n number of windows get opened up. I don't get that. I have removed all the declarations and Java imports for reducing the length of the code. Please help. Thanks.

Answer 1

Move your timer code and your action listener into the constructor:

//constructor
public TheGame() throws IOException 
{
    super("Simple Drawing");
    setSize(x_width, y_height);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setVisible(true);

    jp = new DrawingPanel();
    add(jp);

    addMouseListener(this);
  // Timer class initiazation--animating the ball

ActionListener action = new ActionListener() {

    @Override
    public void actionPerformed(ActionEvent ae) {
       update();

       repaint();
    }
};
Timer t = new Timer(50,action);

}

Try calling this method from the restart buttons onclick listener:

retry.addMouseListener( new MouseListener(){
     @Override
        public void mouseClicked(MouseEvent e) {
         restartApplication();
        }


//------------------------------------------------------------------------------

public void restartApplication()
{
  final String javaBin = System.getProperty("java.home") + File.separator + "bin" + File.separator + "java";
  final File currentJar = new File(TheGame.class.getProtectionDomain().getCodeSource().getLocation().toURI());

  /* is it a jar file? */
  if(!currentJar.getName().endsWith(".jar"))
    return;

  /* Build command: java -jar application.jar */
  final ArrayList<String> command = new ArrayList<String>();
  command.add(javaBin);
  command.add("-jar");
  command.add(currentJar.getPath());

  final ProcessBuilder builder = new ProcessBuilder(command);
  builder.start();
  System.exit(0);
}

Answer 2

Restructure your program such that your display code is independent from your game code

Create another class, a GameDisplay, that holds your JFrame and other swing components, and that manages mouse and keyboard events. In fact, it's best practice to create several classes to manage all this, but one is sufficient for this purpose. Then, have your GameDisplay contain a Game, and call the Game's methods in response to events. Once you have done that, you can restart the game simply by constructing a new Game instance and having your GameDisplay begin using the new instance instead.