Re: [Ikvm-developers] NoClassDefFoundError occurred

[Volker B. <vol...@go...>]

Hi,

First the general questions:
Which IKVM version do you use?
Which classloader do you use? See also the wiki at
http://sourceforge.net/apps/mediawiki/ikvm/index.php?title=ClassLoader

Volker
 

> -----Ursprungliche Nachricht-----
> Von: Frank Bergmann [mailto:fbergman@u.washington.edu] 
> Gesendet: Dienstag, 3. November 2009 20:14
> An: ikv...@li...
> Betreff: [Ikvm-developers] NoClassDefFoundError occurred
> 
> Hello, 
> 
> First of all let me say how much I appreciate all the hard 
> work you do with
> ikvm it is simply amazing and has changed the way we will deploy our
> software from now on. However, I am facing problems and it 
> would be great if
> you could help me out. 
> 
> I'm using ikvmc generated assemblies that allow me to access 
> the qtjambi
> framework:
> 
> http://code.google.com/p/qt4dotnet/
> 
> and mostly things work just fine, at least as long as I 
> confine myself to
> never use .Net objects in a class used by qtjambi. However 
> for my current
> project I'm stumped. I need to define my own object inherited from
> QGraphicsScene, which works great up to the point where 
> qtjambi is using it
> (here in a custom QGraphicsItem::itemChange method). So I was 
> hoping you
> could tell me what I could do to make it work. I think I saw 
> on the IKVM
> website that it should be possible to refer to CLI objects. 
> Here the error I
> get: 
> 
> 
> public class MyItem: QGraphicsItemGroup
> {
> public override object 
> itemChange(QGraphicsItem.GraphicsItemChange change,
> object value)
>         {
>             if (change ==
> QGraphicsItem.GraphicsItemChange.ItemPositionChange)
>             {
>                 UpdateTheItem();
> 
>                 return value;
>             }
> 
>             return base.itemChange(change, value); //<---- BOOOOM
>         }
> 
> ....
> }
> 
> The Exception: 
> 
> Java.lang.NoClassDefFoundError {"cli/MyGraphicsScene"}
> 
>    at IKVM.Runtime.JNI.Frame.Leave()
>    at
> com.trolltech.qt.gui.QGraphicsItemGroup.__qt_itemChange_Graphi
> csItemChange_O
> bject(Int64 , Int32 , Object )
>    at 
> com.trolltech.qt.gui.QGraphicsItemGroup.itemChange(GraphicsItemChange
> change, Object value)
>    at 
> BenZaiTenQt.GraphicItems.QSpeciesItem.itemChange(GraphicsItemChange
> change, Object value) in MyItem.cs:line 167
> 
> 
> and here the definition of the scene: 
> 
> public class MyGraphicsScene : QGraphicsScene
>     {
>         
>         
>         public MyGraphicsScene(QObject parent)
>             : base(parent)
>         {
>             Initialize();
>         }
>         public MyGraphicsScene(QRectF sceneRect, QObject parent)
>             : base(sceneRect, parent)
>         {
>             Initialize();
>         }
>         public MyGraphicsScene(double x, double y, double 
> width, double
> height, QObject parent)
>             : base(x, y, width, height, parent)
>         {
>             Initialize();
>         }
>         public MyGraphicsScene(QRectF sceneRect)
>             : base(sceneRect)
>         {
>             Initialize();
>         }
>         public MyGraphicsScene(double x, double y, double 
> width, double
> height)
>             : base(x, y, width, height)
>         {
>             Initialize();
>         }
>         protected internal 
> MyGraphicsScene(QtJambiObject.QPrivateConstructor
> p)
>             : base(p)
>         {
>             Initialize();
>         }
> 
>         private void Initialize()
>         {
>             
>         }
>          
>     }
> 
> Also things like the following seem to fail, I wonder why: 
> 
> public class MyVeryImportantClass { public 
> MyVeryImportantClass () {} } 
> 
> public class MyDialog : QDialog { public 
> MyDialog(MyVeryImportantClass var1)
> { _var1 = var1; } 
> 		public MyVeryImportantClass Helper { get { 
> return _var1; }
> set { _var1 = value;} } }
> 
> where a CLI class is referenced will just fail with a
> NullReferenceException:
> 
> *** exception in native code ***
> System.NullReferenceException: Object reference not set to an 
> instance of an
> object.
>    at __<Getter>(Object )
>    at
> IKVM.NativeCode.sun.reflect.ReflectionFactory.FieldAccessorImp
> lBase.FastObje
> ctFieldAccessor.get(Object obj)
>    at IKVM.Runtime.JNIEnv.GetObjectField(JNIEnv* pEnv, IntPtr 
> obj, IntPtr
> fieldID)
>    at 
> com.trolltech.qt.gui.QDialog.__qt_QDialog_QWidget_WindowFlags(Int64 ,
> Int32 )
> *** exception in native code ***
> System.NullReferenceException: Object reference not set to an 
> instance of an
> object.
>    at __<Getter>(Object )
>    at
> IKVM.NativeCode.sun.reflect.ReflectionFactory.FieldAccessorImp
> lBase.FastObje
> ctFieldAccessor.get(Object obj)
>    at IKVM.Runtime.JNIEnv.GetObjectField(JNIEnv* pEnv, IntPtr 
> obj, IntPtr
> fieldID)
>    at com.trolltech.qt.core.QObject.__qt_toString(Int64 )
> 
> 
> Thank you so much 
> Best
> frank
> 
> 
> --------------------------------------------------------------
> ----------------
> Come build with us! The BlackBerry(R) Developer Conference in SF, CA
> is the only developer event you need to attend this year. 
> Jumpstart your
> developing skills, take BlackBerry mobile applications to 
> market and stay 
> ahead of the curve. Join us from November 9 - 12, 2009. Register now!
> http://p.sf.net/sfu/devconference
> _______________________________________________
> Ikvm-developers mailing list
> Ikv...@li...
> https://lists.sourceforge.net/lists/listinfo/ikvm-developers
>