unable to added custom swing panel

[NickL]

Hi,

I am using the "Choose Panel" option in the Swing Designer and am experiencing some difficulty. I have a blank JFrame, create using New->Swing->JFrame. It does have anything in it. I select my class from the dialog box that is presented. The class is extended directly from JPanel with a no arg constructor. It was also created using Swing Designer. After selecting it, I go to place it in the contentPane of the JFrame and I get a circle with a line through it as my cursor. There is nowhere to drop it, doesn't work on the blank contentPane or in the tree view. When I click, simply nothing happens. How can I add my panel to the frame?

I'm running Eclipse 3.1 M5a and Swing Designer 3.0.1 on Windows XP Pro SP2, command line= "C:\Program Files\eclipse\eclipse.exe" -vmargs -Xms128M -Xmx256M

[Eric Clayberg]

I am using the "Choose Panel" option in the Swing Designer and am experiencing some difficulty. I have a blank JFrame, create using New->Swing->JFrame. It does have anything in it. I select my class from the dialog box that is presented. The class is extended directly from JPanel with a no arg constructor. It was also created using Swing Designer. After selecting it, I go to place it in the contentPane of the JFrame and I get a circle with a line through it as my cursor. There is nowhere to drop it, doesn't work on the blank contentPane or in the tree view. When I click, simply nothing happens. How can I add my panel to the frame?

Check your Eclipse ".log" for any errors. Also check your project's /bin directory to make sure that a .class file exists for your JPanel. Designer can't add a custom widget unless it has been compiled and is available on your project's classpath.

[NickL]

Where should I look for the .log file? I checked my /bin, the JPanel is compiled. Eclipse compiles classes automatically, right? Is there some way this could go wrong? I tried cleaning the project and recompiling, didn't help this problem.

[NickL]

I should also mention that this worked the first time I tried it, then I added an argument to the constructor of the JPanel and this caused a big red box to appear in the frame instead of my panel.

I removed the argument from the constructor, deleted the red box and tried to reinsert my panel into the frame, but was unable to do so. Like I said, I have cleaned the project, toggled auto building and recomplied everything trying to get it to take but no dice.

Thanks for your help!

[Eric Clayberg]

Where should I look for the .log file?

It is in your <workspace>/.metadata directory.

Custom widgets must also have a zero-argument constructor.

[NickL]

Ok, here's the error that appears in the log when I perform the sequence I described earlier:

com.swtdesigner.properties.PropertyException: java.lang.NullPointerException
at com.swtdesigner.model.swing.component.custom.ContainerBeanWithPropertyChildrenInfo.ensureBeanInstance(ContainerBeanWithPropertyChildrenInfo.java:323)
at com.swtdesigner.model.swing.component.custom.WorkspaceContainerBeanInfo.isBean(WorkspaceContainerBeanInfo.java:191)
at com.swtdesigner.model.swing.component.custom.WorkspaceContainerBeanInfo.fetchDefaultValuesForPropertyDescriptors(WorkspaceContainerBeanInfo.java:181)
at com.swtdesigner.model.swing.JavaBeanInfo.initClassAndBounds(JavaBeanInfo.java:635)
at com.swtdesigner.model.swing.JavaBeanInfo.<init>(JavaBeanInfo.java:160)
at com.swtdesigner.model.swing.component.ComponentBeanInfo.<init>(ComponentBeanInfo.java:106)
at com.swtdesigner.model.swing.component.ContainerBeanInfo.<init>(ContainerBeanInfo.java:97)
at com.swtdesigner.model.swing.component.custom.ContainerBeanWithPropertyChildrenInfo.<init>(ContainerBeanWithPropertyChildrenInfo.java:51)
at com.swtdesigner.model.swing.component.custom.WorkspaceContainerBeanInfo.<init>(WorkspaceContainerBeanInfo.java:51)
at com.swtdesigner.gef.tools.swing.SwingBeanCreationToolEntry$1.getNewObject(SwingBeanCreationToolEntry.java:114)
at org.eclipse.gef.requests.CreateRequest.getNewObject(CreateRequest.java:72)
at com.swtdesigner.gef.policy.swing.layout.border.BorderLayoutEditPolicy.getCreateCommand(BorderLayoutEditPolicy.java:211)
at org.eclipse.gef.editpolicies.LayoutEditPolicy.getCommand(LayoutEditPolicy.java:175)
at org.eclipse.gef.editparts.AbstractEditPart.getCommand(AbstractEditPart.java:494)
at org.eclipse.gef.tools.TargetingTool.getCommand(TargetingTool.java:111)
at org.eclipse.gef.tools.CreationTool.handleMove(CreationTool.java:183)
at org.eclipse.gef.tools.AbstractTool.mouseMove(AbstractTool.java:992)
at org.eclipse.gef.EditDomain.mouseMove(EditDomain.java:221)
at com.swtdesigner.gef.DesignerEditDomain.mouseMove(DesignerEditDomain.java:206)
at org.eclipse.gef.ui.parts.DomainEventDispatcher.dispatchMouseMoved(DomainEventDispatcher.java:331)
at org.eclipse.draw2d.LightweightSystem$EventHandler.mouseMove(LightweightSystem.java:506)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:144)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:82)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:842)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:2908)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2541)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:1612)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1578)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:293)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:144)
at org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplication.java:102)
at org.eclipse.core.internal.runtime.PlatformActivator$1.run(PlatformActivator.java:228)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:333)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:150)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.core.launcher.Main.invokeFramework(Main.java:268)
at org.eclipse.core.launcher.Main.basicRun(Main.java:260)
at org.eclipse.core.launcher.Main.run(Main.java:887)
at org.eclipse.core.launcher.Main.main(Main.java:871)
Caused by: java.lang.NullPointerException
at edu.virginia.speclab.juxta.diff.viewer.CollationViewer.highlightDifferences(CollationViewer.java:75)
at edu.virginia.speclab.juxta.diff.viewer.CollationViewer.<init>(CollationViewer.java:36)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.swtdesigner.model.swing.component.custom.ContainerBeanWithPropertyChildrenInfo$1.run(ContainerBeanWithPropertyChildrenInfo.java:300)

[Eric Clayberg]

Ok, here's the error that appears in the log when I perform the sequence I described earlier

The error indicates that it can't instantiate your custom widget for some reason.

If you want to send us the class, we can try it on our end.