Casting java objects in RPG

["Larry Ducie" <larry_ducie@xxxxxxxxxxx>]

Hi everyone,

I have a question regarding the ability to cast java objects via the RPG - 
Java interface.

Basically, I have a java program that performs xslt transforms on some xml. 
To do this you need to pass a javax.xml.transform.Source object to the 
transformer. Now this is actually an interface and can only be created by 
instantiating an object that implements the interface (I believe). You can 
then cast the object accordingly.

I cast during construction as below:

javax.xml.transform.Source xmlSource =
               new javax.xml.transform.stream.StreamSource(xmlFile);

To prototype this method in RPG would give you something like:

* new StreamSource( File )...
D new_StreamSource...
D                 pr              O   EXTPROC(*JAVA
D                                     :'javax.xml.transform-
D                                     .stream.StreamSource'
D                                     :*CONSTRUCTOR)
D                                     Class(*JAVA
D                                     :'javax.xml.transform-
D                                     .Source')
D File                            O   Class(*JAVA
D                                     :'java.io.File')

But, of course, I get the following message if I try this: 'The return value 
of a Java constructor must have the same class as the method.' (I'm trying 
to use the StreamSource constructor to create a StreamSource object cast as 
a Source object)

As javax.xml.transform.Source is an interface I can't simply instantiate it 
can I?

Does anybody have any ideas on how I can cast a concrete object to an 
abstract object in RPG?

Am I missing something really simple here?

Cheers

Larry Ducie