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Thread: Images works on an applet, but doesn't work when an applet is in a JFrame.

  1. #26
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    Default Re: Images works on an applet, but doesn't work when an applet is in a JFrame.

    i understand that, but can't figure out, how to load images only once.

    i do load same image for all blocks. and sometimes when the ball hits a block, errors appears:
    Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
    	at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
    	at java.util.AbstractList$Itr.next(Unknown Source)
     
    	at Zaidimas.Main.paint(Main.java:229)
    	at Zaidimas.Main.update(Main.java:189)
     
    	at sun.awt.RepaintArea.updateComponent(Unknown Source)
    	at sun.awt.RepaintArea.paint(Unknown Source)
    	at sun.awt.windows.WComponentPeer.handleEvent(Unknown Source)
    	at java.awt.Component.dispatchEventImpl(Unknown Source)
    	at java.awt.Container.dispatchEventImpl(Unknown Source)
    	at java.awt.Component.dispatchEvent(Unknown Source)
    	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    	at java.awt.EventQueue.access$000(Unknown Source)
    	at java.awt.EventQueue$1.run(Unknown Source)
    	at java.awt.EventQueue$1.run(Unknown Source)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    	at java.awt.EventQueue$2.run(Unknown Source)
    	at java.awt.EventQueue$2.run(Unknown Source)
    	at java.security.AccessController.doPrivileged(Native Method)
    	at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    	at java.awt.EventQueue.dispatchEvent(Unknown Source)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    	at java.awt.EventDispatchThread.run(Unknown Source)

    My paint method:

    public void paint(Graphics g){
    //background
    		try {
    			url_bg = getClass().getResource("bg.png");
    			bg = ImageIO.read(url_bg);
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		g.drawImage(bg, 0, 0, this);
     
    //ball		
    		ball.Draw(g);
     
    //paddle
     
    		try {
    			url_paddle = getClass().getResource("paddle.png");
    			paddle = ImageIO.read(url_paddle);
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		g.drawImage(paddle, paddle.x, paddle.y, this);
     
    //blocks
     
    		for(Block b : blocks){
    			b.draw(g);
    			try {
    				url_block = getClass().getResource("block.png");
    				block = ImageIO.read(url_block);
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			g.drawImage(block, b.x, b.y, this);
     
    		}

    My update method (find this on youtube, to reduce/remove flickering in an applet):
    private Image dbImage;	
    private Graphics dbGraphics;
     
    public void update(Graphics g){
    		if (dbImage == null)
    		{
    			dbImage = createImage(this.getSize().width, this.getSize().height);
    			dbGraphics = dbImage.getGraphics();
    		}
     
    		dbGraphics.setColor(this.getBackground());
    		dbGraphics.fillRect(0, 0, this.getSize().width, this.getSize().height);
     
    		dbGraphics.setColor(this.getForeground());
    		paint(dbGraphics);
    		g.drawImage(dbImage, 0, 0, this);
     
    	}

  2. #27
    Super Moderator Norm's Avatar
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    Default Re: Images works on an applet, but doesn't work when an applet is in a JFrame.

    java.util.ConcurrentModificationException
    Are you changing a List while iterating through it?
    Have you read the API doc for that exception? Its doc is in with the doc for all the classes.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following User Says Thank You to Norm For This Useful Post:

    scorpas (May 18th, 2012)

  4. #28
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    Default Re: Images works on an applet, but doesn't work when an applet is in a JFrame.

    Quote Originally Posted by Norm View Post
    Are you changing a List while iterating through it?
    Have you read the API doc for that exception? Its doc is in with the doc for all the classes.
    if i understand what u asking, then:
    i have array list of blocks (bricks).
    when an applet is running blocks are destroying by a ball collision. So yes, list are changing while the game is playing.

    so, how to load images only once?

    edit: i fixed lag, by putting ImageIO.read methods to my init() method,
    Last edited by scorpas; May 18th, 2012 at 01:54 PM.

  5. #29
    Super Moderator Norm's Avatar
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    Default Re: Images works on an applet, but doesn't work when an applet is in a JFrame.

    so, how to load images only once?
    Don't load them twice.
    Put the load of the images in a method that is only called one time.
    Define the image variables as class variables.
    If you don't understand my answer, don't ignore it, ask a question.

  6. The Following User Says Thank You to Norm For This Useful Post:

    scorpas (May 18th, 2012)

  7. #30
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    Default Re: Images works on an applet, but doesn't work when an applet is in a JFrame.

    ok, done, this one is SOLVED.
    Big thanks to Norm.

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