Tharindu, Yes, learning basics is a proper thing to do. I found your article much better than the book I had read [1].
[1] Kathy Walrath, Mary Campione The JFC Swing Tutorial http://books.google.com/books?id=3rWTX-vjUhEC&printsec=frontcover On Fri, Apr 4, 2008 at 8:59 PM, Tharindu Mathew <[EMAIL PROTECTED]> wrote: > Before digging deep on the problem, I feel I should understand the Swing > subsystem more. I'm reading the following article to get a proper idea. > > http://java.sun.com/products/jfc/tsc/articles/architecture/ > > Please tell me if there is more relevant articles that will help me along > the way. Thanks for the help. > > > On Fri, Apr 4, 2008 at 7:17 PM, Alexei Fedotov <[EMAIL PROTECTED]> > wrote: > > > > > Tharindu, > > Thanks for the question. If I understand you correctly UIDefaults hash > > table does not contain a proper value for a method to call for the key > > corresponding to JRootPane.class. Why? The brief answer is "I don't > > know". Keep digging deeper. BTW, do we have swing gurus on the list > > who could shed the light on the problem? > > > > To guess what should be in the method variable I suggest you setting a > > breakpoint on this line and try to collect a statistics for working > > swing demos. Why do they work? If JRootPanne would work, it probably > > has a different look and feel or setup in standard demos. > > > > I like that you have come with the guess. I checked how setUI() is > > called from java/common/javax/swing/JRootPane.java: it is mentioned > > three times as in other components. So, keeping an eye on this method > > does not help. I believe someone should register a method for this > > class in UIDefaults, for example, call new UIDefaults(a proper array). > > I found that this is done in the following places. > > > > $ grep -rlI 'new UIDefaults' ./java/common/javax/swing/* | grep -v svn > > ./java/common/javax/swing/LookAndFeel.java > > ./java/common/javax/swing/UIManager.java > > ./java/common/javax/swing/plaf/basic/BasicLookAndFeel.java > > ./java/common/javax/swing/plaf/metal/MetalLookAndFeel.java > > ./java/common/javax/swing/plaf/multi/MultiLookAndFeel.java > > ./java/common/javax/swing/plaf/synth/SynthLookAndFeel.java > > ./java/common/javax/swing/text/AbstractDocument.java > > > > Based on this list I may guess that the chosen look and feel does not > > register JRootPane look and feel correctly. Please, keep us posted on > > your advances. > > > > Thanks! > > > > On Fri, Apr 4, 2008 at 10:12 AM, Tharindu Mathew <[EMAIL PROTECTED]> > > wrote: > > > ERROR: UIDefaults.getUI() failed: java.lang.NullPointerException > > > at javax.swing.UIDefaults.getUI(UIDefaults.java:339) > > > at javax.swing.UIManager.getUI(UIManager.java:222) > > > at javax.swing.JPanel.updateUI(JPanel.java:141) > > > at javax.swing.JPanel.<init>(JPanel.java:56) > > > at javax.swing.JPanel.<init>(JPanel.java:76) > > > at javax.swing.JRootPane.createGlassPane(JRootPane.java:278) > > > at javax.swing.JRootPane.<init>(JRootPane.java:78) > > > at javax.swing.JFrame.createRootPane(JFrame.java:175) > > > at javax.swing.JFrame.frameInit(JFrame.java:393) > > > at javax.swing.JFrame.<init>(JFrame.java:123) > > > at > > > > > net.sf.freecol.client.gui.FullScreenFrame.<init>(FullScreenFrame.java:34) > > > at > > net.sf.freecol.client.FreeColClient.startGUI(FreeColClient.java:218) > > > at > > net.sf.freecol.client.FreeColClient.access$000(FreeColClient.java:31) > > > at net.sf.freecol.client.FreeColClient$1.run(FreeColClient.java:142) > > > at > > java.awt.event.InvocationEvent.runAndNotify(InvocationEvent.java:98) > > > at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:78) > > > at > > java.awt.EventQueueCore.dispatchEventImpl(EventQueueCore.java:138) > > > at java.awt.EventQueue.dispatchEvent(EventQueue.java:144) > > > at > > > java.awt.EventDispatchThread.runModalLoop(EventDispatchThread.java:74) > > > at java.awt.EventDispatchThread.run(EventDispatchThread.java:48) > > > > > > > > > In the UI defaults class: > > > > > > Method method = null; > > > if (uiClass == null) { > > > uiClass = getUIClass(classID, > > > comp.getClass().getClassLoader()); > > > method = getCreateUIMethodPriveledged(uiClass); > > > > > > put(fullClassName, uiClass); > > > put(uiClass, method); > > > } else { > > > method = (Method)get(uiClass); *<--- method is null, > > because > > > no value exists for the uiClass key* > > > } > > > return (ComponentUI)method.invoke(null, new Object[] { comp > > }); > > > *<--- causes NPE when tryin to invoke* > > > > > > What is supposed to return to the method variable? Does this return > > null > > > because the setUI() method is not called from within JRootPane? > > > > > > -- > > > Regards, > > > > > > Tharindu > > > > > > > > > > > -- > > With best regards, > > Alexei > > > > > > -- > Regards, > > Tharindu > -- With best regards, Alexei
