Re: How to implement a java interface in c++?

[mirleau at bluewin dot ch]

>The only way I see for you is the subclass in java code
>and impement all methods of that class in C++. Thats easily possible
>with CNI. And it should be fast.
>
>
>Michael

Hi, thanks for your suggestion, I'd like to try it, but I'm not
expert enough to do what I think you meant. Here's what I did:

I wrote a java subclass:
====CppImplementation.java========================
public class CppImplementation implements JavaInterface
{
    public void doIt(){int a = 1;}
}
=====================================

And used gcjh to generate a header file:

====CppImplementation.h=================================
// DO NOT EDIT THIS FILE - it is machine generated -*- c++ -*-

#ifndef __CppImplementation__
#define __CppImplementation__

#pragma interface

#include <java/lang/Object.h>

extern "Java"
{
  class CppImplementation;
};

class ::CppImplementation : public ::java::lang::Object
{
public:
  virtual void doIt ();
  CppImplementation ();

  static ::java::lang::Class class$;
};

#endif /* __CppImplementation__ */


==============================================

The way I interpret your answer is that I could now forget the
java class and just directly implement this header file in c++.

I'm not certain on how to do that. I guess I need to use
gcj conventions to correctly implement it.

For example I was playing around by in-/out commenting some lines
below, but that didn't work out link-wise: (vtables and Object::Object()):
============ CppImplementation.cc =================
#include "CppImplementation.h" // generated by gcjh

// #pragma interface

#include <java/lang/Object.h>

//extern "Java"
//{
//  class CppImplementation;
//};

void CppImplementation::doIt (){};
CppImplementation::CppImplementation (){};
::java::lang::Class CppImplementation::class$;

===================================================

Is there an example around where it says how to implement such
a generated header file yourself?
By the way is there a pdf version of the gcj manual somewhere?
Or actually a document that I can print in one go?

Thanks, Olivier