ObjectInputStream

[Adam Bell]

I'm having some problems with ObjectInputStream, using weka again.  If I create a weka.classifiers.functions.MultilayerPerceptron and train it and save it (ObjectOutputStream ) then when I try to load it again(ObjectInputStream) I am getting this error:

Type:java.lang.ClassNotFoundException
Message:weka.classifiers.functions.neural.SigmoidUnit
Source:IKVM.OpenJDK.ClassLibrary
TargetSite:System.Object readObject()
HelpLink:null
TargetSite:System.Object readObject()
HelpLink:null
StackTrace:

   at java.io.ObjectInputStream.readObject()
   at WekaRunner.IO.LoadClassifier(String path) in C:\Documents and Settings\Adam\My Documents\Source\Csharp\General\NV2\Weka\Weka\IO.cs:line 88

It can't find 'weka.classifiers.functions.neural.SigmoidUnit', which exists?

Any idea whats going on here?
Adam


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[Jeroen Frijters]

Adam Bell wrote:

> I'm having some problems with ObjectInputStream, using weka again.  If
> I create a weka.classifiers.functions.MultilayerPerceptron and train it
> and save it (ObjectOutputStream ) then when I try to load it
> again(ObjectInputStream) I am getting this error:
>
> Type:java.lang.ClassNotFoundException
> Message:weka.classifiers.functions.neural.SigmoidUnit
> Source:IKVM.OpenJDK.ClassLibrary
> TargetSite:System.Object readObject()
> HelpLink:null
> TargetSite:System.Object readObject()
> HelpLink:null
> StackTrace:
>
>    at java.io.ObjectInputStream.readObject()
>    at WekaRunner.IO.LoadClassifier(String path) in C:\Documents and
> Settings\Adam\My
> Documents\Source\Csharp\General\NV2\Weka\Weka\IO.cs:line 88
>
> It can't find 'weka.classifiers.functions.neural.SigmoidUnit', which
> exists?
>
> Any idea whats going on here?

The class may exist, but the class loader that is used can't find the class. ObjectInputStream uses the first non-null class loader on the call stack and if that happens to be an assembly class loader for an assembly that doesn't reference the weka assembly it won't be able to load from it.

You can either make sure that that assembly has a reference to the weka assembly, or you can override ObjectInputStream.resolveClass() to do resolve the class yourself.

Regards,
Jeroen

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