My apologies to Matthias, I gave him a bogus answer (referencing the
newInstance on
the Object class rather than the newInstance(Object o) method on Field
handler.
I would think that what he is doing should work.... I'm also interested
in the solution
to his problem.
Is there a simple, self contained example of using a FieldHandler somewhere
in the castor source directory ?
or online somewhere ?
thanks to whoever can help.
Chris
----- Original Message -----
From: "Keith Visco" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, December 16, 2002 12:14 PM
Subject: Re: [castor-dev] NotConstructable Exception and FieldHandler
>
> You can also create a "valueOf" method that takes a string value and
> returns the proper enumeration instance, which is how Castor deals with
> unmarshalling type-safe enumerations:
>
> public static [object-type] valueOf(String enumValue) {
>
> }
>
> --Keith
>
> -------- Original Message --------
> Subject: Re: [castor-dev] NotConstructable Exception and FieldHandler
> Date: Mon, 16 Dec 2002 11:55:54 -0800
> From: "Chris Bedford" <[EMAIL PROTECTED]>
> Reply-To: [EMAIL PROTECTED]
> To: [EMAIL PROTECTED]
> References: <[EMAIL PROTECTED]>
>
> Hi, Matthias: I'm no Castor expert,but I can tell you that
> Class.newInstance() requires a no argument constructor be available on
> theClass whose instance you are trying to construct. From the
> Javadocs-> ****************
>
> public Object newInstance()
> throws InstantiationException,
> IllegalAccessException
>
> Creates a new instance of the class represented by this Class object.
> The class is instantiatied as if by a new expression with an empty
> argument list. The class is initialized if it has not already been
> initialized. **************** As a workaround you could create a
> pass-through proxy that for CoordinateFormatEnum that knows how to
> constructan instance of a CoordinateFormatEnum. This proxy would
> implement all methods of CoordinateFormatEnum and justdelegate the calls
> to the embedded CoordinateFormatEnum instance. That's one way... maybe
> the Castor guys can suggest a better one.. I'd be interested in
> finding out as well since I find creationof these proxies to be a
> hassle.. but they get the job done. thanks Chris
>
> ----- Original Message -----
> From: Matthias David
> To: [EMAIL PROTECTED]
> Sent: Monday, December 16, 2002 1:39 AM
> Subject: [castor-dev] NotConstructable Exception and
> FieldHandler
> Hi,
>
> I have written a FieldHandler for a class
> (CoordinateFormatEnum) that has no public constructor. When
> Unmarshalling I get the following exception:
>
> Nested error: org.exolab.castor.mapping.MappingException: The
> Java class CoordinateFormatEnum is not constructable -- it
> does not contain a default public constructor)
>
> The problem is that the class CoordinateFormatEnum is a
> tool-generated class, so I have no chance to make the
> constructor public. So How can this problem be solved? I
> thought that the Unmarshaller does not need to call the
> constructor of the class since the FieldHandler is responsible
> for that, e.g. using the method "newInstance".
>
> Here's the handler's code:
>
> public class CoordinateFormatEnumFieldHandler implements
> FieldHandler {
>
> public Object getValue(Object object)
> throws IllegalStateException {
> return ((Coordinates)object).getFormat().getValue();
> }
>
> public void setValue(Object object, Object value)
> throws IllegalStateException,
> IllegalArgumentException {
>
>
((Coordinates)object).setFormat(CoordinateFormatEnum.fromString((String)valu
e));
>
> }
>
> public void resetValue(Object object)
> throws IllegalStateException,
> IllegalArgumentException {
> }
>
> public void checkValidity(Object object)
> throws ValidityException, IllegalStateException {
> }
>
> public Object newInstance(Object parent)
> throws IllegalStateException {
> return CoordinateFormatEnum.Mercator;
> }
> }
>
> And here's the mapping:
>
> <class name="com.Coordinates" access="shared">
> <description>Default mapping for
> Coordinates</description>
> <map-to xml="Coordinates"/>
> <field name="format" type="com.CoordinateFormatEnum"
> handler="com.CoordinateFormatEnumFieldHandler">
> <bind-xml name="Format" node="attribute"/>
> </field>
> </class>
>
> Any clues for that?
>
> Thanks,
> Matthias.
>
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