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Thread: Ping Pong Game Problem with ball Drop and Catch

  1. #1
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    Default Ping Pong Game Problem with ball Drop and Catch

    I have created this ping pong game but having problem with ball and paddle collusion. After first collusion it gives score 1 but later it never touch the paddle.
    Can anyone help with the code:
    import javax.swing.*;
    import java.awt.*;
    import java.awt.event.*;
    import java.awt.geom.*;
    import java.util.Random.*;
    import javax.swing.ImageIcon;
     
    public class Ball extends JFrame implements ActionListener, KeyListener{
    	int xSpeed=0;
    	int x,y;
    	int x1,y1;
    	int score;
    	int randomNum;
        Rectangle blockRect;
        Rectangle ballRect;
    	Timer time;
    	public Ball(String title){
    		super(title);
    		xSpeed=5;
    		x=400;
    		y=100;
    		x1= 325;
    		y1= 500;
    		time=new Timer(100,this);
    		time.start();
    		blockRect = new Rectangle(x1,y1,150,70);
    		addKeyListener(this);
    		setSize(800,600);
    		setVisible(true);
    		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	}
    	public void actionPerformed(ActionEvent e){
    		y=y+xSpeed;
    		repaint();
    		if(y> this.getWidth()){
    			y=25;
    			score -=1;
    		}
    		if(blockRect.intersects(ballRect)){
    			y=40;
    			score +=1;
    			x =200;
    			y = 300;
    		}
    	}
    	public void paint(Graphics g){
    		Graphics2D g2d=(Graphics2D) g;
    		Rectangle rect=new Rectangle(0,0,800,600);
    		g2d.setColor(Color.BLACK);
    		g2d.fill(rect);
    		g2d.setColor(Color.CYAN);
    		g2d.fillOval(x,y,25,25);
    		ballRect=new Rectangle(x,y,30,30);
    		g2d.setColor(Color.RED);
    		g2d.fillRect(x1,y1,150,40);
    		g2d.drawString("Score:" +score,500,50);
    	}
        public void left() {
            x1-=5;
        }
        public void right() {
            x1 +=5;;
        }
        public void keyReleased(KeyEvent e)
        	{}
        public void keyTyped(KeyEvent e)
        	{}
        public void keyPressed(KeyEvent e)
        	{
            if (e.getKeyCode()==KeyEvent.VK_LEFT){
            	left();
            	System.out.println("Left:"+x1);
            }
            if (e.getKeyCode()==KeyEvent.VK_RIGHT){
            	  right();
            	  System.out.println("Left:"+x1);
            }
        }
    	public static void main(String args[]){
    		new Ball("Animated Ball");
    	}
    }


    --- Update ---

    I think something is wrong here:
    public void actionPerformed(ActionEvent e){
    y=y+xSpeed;
    repaint();
    if(y> this.getWidth()){
    y=25;
    score -=1;
    }
    if(blockRect.intersects(ballRect)){
    y=40;
    score +=1;
    x =200;
    y = 300;
    }


  2. #2
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    Default Re: Ping Pong Game Problem with ball Drop and Catch

    A general architecture comment:

    Don't draw directly on the JFrame by overriding its paint() method. That is not how painting in Swing is intended to be done. Instead, add a JPanel to the JFrame and draw on the JPanel using its paintComponent() method.

    As for your question, perhaps its the placement of your repaint() call, though I'm not sure I understand what you're asking.

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: Ping Pong Game Problem with ball Drop and Catch

    The comparison of y with the width seems confused. Shouldn't y be compared to the height?
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Ping Pong Game Problem with ball Drop and Catch

    can anyone re-write the code I made mistake. I am trying to figure it out for many days without luck.

  5. #5
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    Default Re: Ping Pong Game Problem with ball Drop and Catch

    Make a small change to the code by doing what Greg suggested: Create a JPanel with the current paint() method renamed to paintComponent() and adding an instance of that new JPanel to the JFrame.

    Is getWidth() correct for comparing with y?
    If you don't understand my answer, don't ignore it, ask a question.

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