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Java Forum / General / April 2006Newbie needs help with gcj
I am trying to teach myself java. In order to actually understand the basics, I am using command line tools and not a full blown IDE. I am using the O'Reilly book "Learning Java" (Tiger). I am running a Debian GNU/Linux box. The introductory programs include the obligatory console based "Hello, Java" and four others that use javax.swing and add various eye-candy. They all compile fine with javac and run with the "java" VM. I decided to try and compile them natively using gcj (just for chuckles and grins). The console based program compiles and runs just fine. The others compile, but then give me the following run time errors: ~/Projects/Java$ hello-java1 Exception in thread "main" java.lang.Error: not implemented at javax.swing.UIDefaults.put(java.lang.Object, java.lang.Object) (/usr/lib/libgcj.so.4.0.0) at javax.swing.plaf.basic.BasicDefaults.BasicDefaults() (/usr/lib/libgcj.so.4.0.0) at javax.swing.plaf.metal.MetalLookAndFeel.getDefaults() (/usr/lib/libgcj.so.4.0.0) at javax.swing.UIManager.getDefaults() (/usr/lib/libgcj.so.4.0.0) at javax.swing.UIManager.getUI(javax.swing.JComponent) (/usr/lib/libgcj.so.4.0.0) at javax.swing.JPanel.updateUI() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JPanel.JPanel(java.awt.LayoutManager, boolean) (/usr/lib/libgcj.so.4.0.0) at javax.swing.JPanel.JPanel() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JRootPane.createGlassPane() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JRootPane.getGlassPane() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JRootPane.JRootPane() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JFrame.createRootPane() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JFrame.getRootPane() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JFrame.frameInit() (/usr/lib/libgcj.so.4.0.0) at javax.swing.JFrame.JFrame(java.lang.String) (/usr/lib/libgcj.so.4.0.0) at HelloJava1.main(java.lang.String[]) (Unknown Source) Is there something extra that I need to do with swing programs to get them to compile and run natively using gcj? Marc Shapiro gcj does't not implement all the swing libraries. > I am trying to teach myself java. In order to actually understand the > basics, I am using command line tools and not a full blown IDE. I am [quoted text clipped - 37 lines] > > Marc Shapiro > I am trying to teach myself java. In order to actually understand the > basics, I am using command line tools and not a full blown IDE. I am [quoted text clipped - 11 lines] > Exception in thread "main" java.lang.Error: not implemented > at javax.swing.UIDefaults.put(java.lang.Object, java.lang.Object) <similar errors snipped> > Is there something extra that I need to do with swing programs to get > them to compile and run natively using gcj? gcj doesn't support the whole set of Java classes that are standard with the Sun runtime (JRE) or developer tools (JDK). You can read more about this at the GCJ home page. I recall there are a couple of significant ongoing projects to fill these gaps. You can obtain the Sun JDK for free from Sun. No doubt a Debian package is also available from the usual Debian repositories. I'd suggest you use this unless you have some overriding ethical reason for choosing GNU tools. > gcj doesn't support the whole set of Java classes that are standard with > the Sun runtime (JRE) or developer tools (JDK). You can read more about [quoted text clipped - 5 lines] > use this unless you have some overriding ethical reason for choosing GNU > tools. Not at all. I have the JDK1.5.0_06 installed and that is what I am using. I just wanted to try and play around with compiling to native code instead of to bytecode. That is what I was using gcj for. Does the jdk have a similar compiler? If not, well, it would be nice, but I can live without it since gcj is obviously not yet complete enough to handle anything beyond console programs. For that I could just use python. Marc Shapiro >> gcj doesn't support the whole set of Java classes that are standard >> with the Sun runtime (JRE) or developer tools (JDK). You can read more [quoted text clipped - 10 lines] > code instead of to bytecode. That is what I was using gcj for. Does > the jdk have a similar compiler? There are commercial compilers that can produce native executables (e.g. some versions of JBuilder). I've not tried them. I hear that anything that uses Swing will have to rely on the JRE being installed since Sun prohibits separate deployment of the DLL's that Swing needs. You may be OK if you use SWT instead of Swing. There's lots of interesting stuff out there but I suspect that producing native binaries is non trivial. e.g. http://swingwt.sourceforge.net/ says "Developers deploying to *nix/Win32 can compile natively with GCJ and the applications can be distributed without a VM." But I think you may have to change references to javax.swing in your .java code. > >> gcj doesn't support the whole set of Java classes that are standard > >> with the Sun runtime (JRE) or developer tools (JDK). You can read [quoted text clipped - 15 lines] > since Sun prohibits separate deployment of the DLL's that Swing > needs. You may be OK if you use SWT instead of Swing. Well, separately redistributing the DLLs would be a violation of copyright, but reimplementation would be alright. Doesn't the IBM JDK have a reimplementation of Swing?  SignatureMicah J. Cowan Programmer, musician, typesetting enthusiast, gamer... http://micah.cowan.name/ > There are commercial compilers that can produce native executables (e.g. > some versions of JBuilder). I've not tried them. I hear that anything [quoted text clipped - 7 lines] > and the applications can be distributed without a VM." But I think you > may have to change references to javax.swing in your .java code. It looks like swingwt would do the job, and I may look into it further later on. For now, however, I think that I am probably better off just working my way through a book, or two, dealing with standard java and swing. Until I get the hag of the standard stuff, trying to do other things will probably just add to my confusion. Thanks for the pointer, though. Marc Shapiro ["Followup-To:" header set to comp.lang.java.help.] On 2006-04-06, Marc Shapiro penned: > It looks like swingwt would do the job, and I may look into it > further later on. For now, however, I think that I am probably > better off just working my way through a book, or two, dealing with > standard java and swing. Until I get the hag of the standard stuff, > trying to do other things will probably just add to my confusion. If it makes you feel better, lots of people who've been working in Java for years (myself included) have never compiled a java app to a native binary. I've just never needed to, and it seems like you lose a lot of flexibility by doing so. Signaturemonique Ask smart questions, get good answers: http://www.catb.org/~esr/faqs/smart-questions.html Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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