AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Swing JPanel PaintComponent Issue Goto page 1, 2  Next          AppletTalk.com Forum Index -> Java GUI Toolkits View previous topic :: View next topic   Author Message matt Guest Posted: Mon Nov 29, 2004 1:11 am    Post subject: Swing JPanel PaintComponent Issue I have a JFrame that I have undecorated and in full screen mode. To draw on the screen, I add a JPanel and draw on that and go for a setVisible(true). Then, I do what I need and do a setVisible(false) and go forward. Sometimes, though, my application will just hang and not paint anything - at various `screens' ... I'm not doing any threading stuff in my code, so I don't think that's it. Any ideas? Thanks [ummaycoc@localhost java]$ javac -version javac 1.5.0 javac: no source files Usage: javac <options> <source files> where possible options include: -g Generate all debugging info -g:none Generate no debugging info -g:{lines,vars,source} Generate only some debugging info -nowarn Generate no warnings -verbose Output messages about what the compiler is doing -deprecation Output source locations where deprecated APIs are used -classpath <path> Specify where to find user class files -cp <path> Specify where to find user class files -sourcepath <path> Specify where to find input source files -bootclasspath <path> Override location of bootstrap class files -extdirs <dirs> Override location of installed extensions -endorseddirs <dirs> Override location of endorsed standards path -d <directory> Specify where to place generated class files -encoding <encoding> Specify character encoding used by source files -source <release> Provide source compatibility with specified release -target <release> Generate class files for specific VM version -version Version information -help Print a synopsis of standard options -X Print a synopsis of nonstandard options -J<flag> Pass <flag> directly to the runtime system [ummaycoc@localhost java]$ java -version java version "1.5.0" Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64) Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing) [ummaycoc@localhost java]$ uname -a Linux localhost 2.6.3-7mdk-i686-up-4GB #1 Wed Mar 17 15:17:23 CET 2004 i686 unknown unknown GNU/Linux Back to top John McGrath Guest Posted: Mon Nov 29, 2004 4:34 am    Post subject: Re: Swing JPanel PaintComponent Issue On 11/28/2004 at 8:11:49 PM, matt wrote: Quote: Sometimes, though, my application will just hang and not paint anything - at various `screens' ... I'm not doing any threading stuff in my code, so I don't think that's it. Any ideas? No code, no ideas. -- Regards, John McGrath Back to top matt Guest Posted: Mon Nov 29, 2004 11:11 pm    Post subject: Re: Swing JPanel PaintComponent Issue "John McGrath" <ng (AT) jpmcgrath (DOT) net> wrote Quote: On 11/28/2004 at 8:11:49 PM, matt wrote: Sometimes, though, my application will just hang and not paint anything - at various `screens' ... I'm not doing any threading stuff in my code, so I don't think that's it. Any ideas? No code, no ideas. http://www.cs.drexel.edu/~ummaycoc/mathgame.tgz thanks for any help you can give. ~Matt Back to top Andrew Thompson Guest Posted: Tue Nov 30, 2004 1:20 am    Post subject: Re: Swing JPanel PaintComponent Issue On 29 Nov 2004 15:11:54 -0800, matt wrote: Quote: "John McGrath" <ng (AT) jpmcgrath (DOT) net> wrote On 11/28/2004 at 8:11:49 PM, matt wrote: Sometimes, though, my application will just hang and not paint anything - at various `screens' ... I'm not doing any threading stuff in my code, so I don't think that's it. Any ideas? No code, no ideas. http://www.cs.drexel.edu/~ummaycoc/mathgame.tgz ...hmmm. 23 files amounting to 43.5Kb of code. I don't suppose you have a *short* example that displays the problem? -- Andrew Thompson http://www.PhySci.org/codes/ Web & IT Help http://www.PhySci.org/ Open-source software suite http://www.1point1C.org/ Science & Technology http://www.LensEscapes.com/ Images that escape the mundane Back to top hiwa Guest Posted: Tue Nov 30, 2004 4:36 am    Post subject: Re: Swing JPanel PaintComponent Issue [email]mhm26 (AT) drexel (DOT) edu[/email] (matt) wrote in message news:<13383d7a.0411291511.32c96330 (AT) posting (DOT) google.com>... Quote: "John McGrath" <ng (AT) jpmcgrath (DOT) net> wrote On 11/28/2004 at 8:11:49 PM, matt wrote: Sometimes, though, my application will just hang and not paint anything - at various `screens' ... I'm not doing any threading stuff in my code, so I don't think that's it. Any ideas? No code, no ideas. http://www.cs.drexel.edu/~ummaycoc/mathgame.tgz thanks for any help you can give. ~Matt Ugh! Nope! Please don't do that. See http://www.physci.org/codes/sscce.jsp Back to top John McGrath Guest Posted: Tue Nov 30, 2004 5:26 am    Post subject: Re: Swing JPanel PaintComponent Issue On 11/29/2004 at 6:11:54 PM, matt wrote: Quote: http://www.cs.drexel.edu/~ummaycoc/mathgame.tgz Just looking at the Gui class, I can see that the entire structure of the program is wrong. You need to do some reading on Swing, the AWT event model and threads. You can find some good material on that in "The Java Tutorial" on the Sun web site, but I would also recommend that you take in a good Swing book. However, in a nutshell, you need to know two basic rules: 1) Swing is (for the most part) not thread-safe. That means that you need to update the UI in the Event Dispatch Thread. 2) Swing does painting and other critical functions in the Event Dispatch Thread, so event handlers must do their work and exit quickly. This may sound very constraining, but it really is not. You just need to learn how to put things together. -- Regards, John McGrath Back to top matt Guest Posted: Tue Nov 30, 2004 3:16 pm    Post subject: Re: Swing JPanel PaintComponent Issue "John McGrath" <ng (AT) jpmcgrath (DOT) net> wrote Quote: On 11/29/2004 at 6:11:54 PM, matt wrote: http://www.cs.drexel.edu/~ummaycoc/mathgame.tgz Just looking at the Gui class, I can see that the entire structure of the program is wrong. You need to do some reading on Swing, the AWT event model and threads. You can find some good material on that in "The Java Tutorial" on the Sun web site, but I would also recommend that you take in a good Swing book. However, in a nutshell, you need to know two basic rules: 1) Swing is (for the most part) not thread-safe. That means that you need to update the UI in the Event Dispatch Thread. 2) Swing does painting and other critical functions in the Event Dispatch Thread, so event handlers must do their work and exit quickly. This may sound very constraining, but it really is not. You just need to learn how to put things together. So, I only have the one thread doing anything (the Gui Runnable - the main program is done after main(String[])), so there shouldn't be any issues with what I did (I think). I also don't think my event handlers are that inefficient - but I don't think that's relevant to my problem. It seems that paintComponent() is not even being called in some cases. Back to top Andrew Thompson Guest Posted: Tue Nov 30, 2004 3:34 pm    Post subject: Re: Swing JPanel PaintComponent Issue On 30 Nov 2004 07:16:58 -0800, matt wrote: Quote: It seems .. Please do not waste our time with 'seems'. Find out for sure*. Quote: ...that paintComponent() is not even being called in some cases. public void paintComponent(Graphics g) { // * Put a print statement to check.. System.out.println( "Entered paintComponent()!" ); ... -- Andrew Thompson http://www.PhySci.org/codes/ Web & IT Help http://www.PhySci.org/ Open-source software suite http://www.1point1C.org/ Science & Technology http://www.LensEscapes.com/ Images that escape the mundane Back to top Babu Kalakrishnan Guest Posted: Tue Nov 30, 2004 3:38 pm    Post subject: Re: Swing JPanel PaintComponent Issue matt wrote: Quote: So, I only have the one thread doing anything (the Gui Runnable - the main program is done after main(String[])), so there shouldn't be any issues with what I did (I think). If the "Gui runnable" is something that is running in a thread that was started by you, then it _is_ _not_ the Event Dispatch Thread, and you aren't allowed to do any GUI updates from that thread. There is only a single thread called the EDT which is used by AWT for its event dispatch and paint operations, and that is created automatically by the AWT process. BK Back to top matt Guest Posted: Tue Nov 30, 2004 9:59 pm    Post subject: Re: Swing JPanel PaintComponent Issue Andrew Thompson <SeeMySites (AT) www (DOT) invalid> wrote Quote: On 30 Nov 2004 07:16:58 -0800, matt wrote: It seems .. Please do not waste our time with 'seems'. Find out for sure*. ...that paintComponent() is not even being called in some cases. public void paintComponent(Graphics g) { // * Put a print statement to check.. System.out.println( "Entered paintComponent()!" ); ... So, I had the following: protected final void paintComponent(Graphics g) { super.paintComponent(g); System.out.println(this.getClass().getCanonicalName()) in a class that is a sort of baseclass (extends JPanel) that I extend for drawing my various screens -- so I was already on that ball - I said `it seems' because that is what is happening as far as I could tell (but maybe super.paintComponent(g) was messing up). I'll check later when I get to that machine to see that - but I don't think that would cause any issue. Back to top matt Guest Posted: Tue Nov 30, 2004 10:00 pm    Post subject: Re: Swing JPanel PaintComponent Issue Babu Kalakrishnan <k.a.l.a (AT) sankya (DOT) com> wrote Quote: matt wrote: So, I only have the one thread doing anything (the Gui Runnable - the main program is done after main(String[])), so there shouldn't be any issues with what I did (I think). If the "Gui runnable" is something that is running in a thread that was started by you, then it _is_ _not_ the Event Dispatch Thread, and you aren't allowed to do any GUI updates from that thread. There is only a single thread called the EDT which is used by AWT for its event dispatch and paint operations, and that is created automatically by the AWT process. BK My thread doesn't call paint - it just instantiates objects that are subclasses of JPanel that are added to a JFrame -- so I'm not doing any updating from my thread. ~Me! Back to top hiwa Guest Posted: Wed Dec 01, 2004 12:39 am    Post subject: Re: Swing JPanel PaintComponent Issue From Gui.java: This is wrong: Quote: new Thread(new Gui(frame)).run(); And you don't call invokeLater() or invokeAndWait() from you app thread. Everybody can tell you haven't learn Java basics at all!! Back to top John McGrath Guest Posted: Wed Dec 01, 2004 2:11 am    Post subject: Re: Swing JPanel PaintComponent Issue On 11/30/2004 at 5:00:43 PM, matt wrote: Quote: My thread doesn't call paint - it just instantiates objects that are subclasses of JPanel that are added to a JFrame -- so I'm not doing any updating from my thread. Matt, Here are some rather simple things you need to listen to and understand: 1) Your code is not going to work the way it is put together. 2) You may think you understand the correct structure and operation of Swing / AWT programs, but you *really* do not. 3) The people who are telling you this *do* understand Swing and AWT. At least some of them understand it better than just about anyone you are likely to meet. 4) People in these newsgroups are willing to spend time helping others, but those seeking help need to bring themselves to a point where they can understand what they are being told, without requiring others to write a book for them. As such, you need to get a good Swing book and study it. -- Regards, John McGrath Back to top matt Guest Posted: Wed Dec 01, 2004 3:08 pm    Post subject: Re: Swing JPanel PaintComponent Issue Quote: 1) Your code is not going to work the way it is put together. I know it's not. That's why I came here. The fact that it working is nondeterministic gives me issues. Quote: 2) You may think you understand the correct structure and operation of Swing / AWT programs, but you *really* do not. No - I don't think I understand the correct operation/structure of the AWT/Swing programs. I try to stay away from Java (it's a *very* poorly designed beast - not that my current incarnation of its use is any better). Quote: 3) The people who are telling you this *do* understand Swing and AWT. At least some of them understand it better than just about anyone you are likely to meet. I don't think I asserted otherwise. Quote: 4) People in these newsgroups are willing to spend time helping others, but those seeking help need to bring themselves to a point where they can understand what they are being told, without requiring others to write a book for them. As such, you need to get a good Swing book and study it. So, people said "It may be x" and I said "I don't think it is X because of Y" - clearly I may not have an understanding of how X and Y interact in the java model of reality. So I was trying to do what you said - bring myself to understanding by presenting my view of the scenario - but you seem to assert otherwise, and it seems like you came off as quite rude/curt in doing so, something you may wish to look into considering you are presenting yourself as a facet of a community (java/swing/awt). I'm working on a short example to reproduce the error -- I hope the community can still help me when I have it. Thanks, Matthew Maycock Back to top Andrew Thompson Guest Posted: Wed Dec 01, 2004 3:32 pm    Post subject: Re: Swing JPanel PaintComponent Issue On 1 Dec 2004 07:08:29 -0800, matt wrote: Quote: I'm working on a short example to reproduce the error .. A sterling idea. For tips on preparing an example that will help others to help you, check the document that hiwa linked to. ( I can personally recommend those tips, since I wrote the document . -- Andrew Thompson http://www.PhySci.org/codes/ Web & IT Help http://www.PhySci.org/ Open-source software suite http://www.1point1C.org/ Science & Technology http://www.LensEscapes.com/ Images that escape the mundane Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java GUI Toolkits All times are GMT Goto page 1, 2  Next Page 1 of 2   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.