Re: Problem

[Andrew Haley <aph at redhat dot com>]

Amit M wrote:
> Hello
>              Here is My problem,
> 
>  I am doing My Last year academic project named "j4cpp wrapper" .In
> this project, I am generating wrapper to call java .class files from
> c++ so that c++ user can just add that wrapper (which will be just a
> header file(.h) ) to invoke methods of that java class file. Here I am
> using Invocation API's (kind of  Reverse JNI ).
> 
> Now my current status is as follows :
> code for Wrapper  generation for basic datatypes (such as
> int,char,float ) and arrays are done.
> But now i got problem when a java class( having any java class library
> object such as Frames etc..in it. )  i dont know how to deal with
> it....how to load them so that c++ user can access to those methods ?
> 
> here is the structure of wrapper which my application generates :
> 
> *wrapper name is same as class file name with .h extension.
> (name of file abc.h)
> #include "jvm.cpp"      // this file does all JVM loading related work.
>  class abc                  // same name as java class name(retrieved
> using reflection api's )
> {
>          private :
>                invocation_api invoke;     //object used to invoke and load JVM.
>           public :
>                abc() {invoke.create_vm();}
> 
>                 void method1(int,int);
> }
> 
> 
> void abc::method1(int arg1, int arg2)
> {
> 
>      jvalue returnValue;
>       Invoke.invoke_class("abc", "method1", "(II)V", &returnValue, arg1, arg2);
>       /* This function resides in jvm.cpp file which is included @top.
> This function takes class name, method name, method signature, jvalue
> reference variable  and arguments if any.  Users are not allowed to
> change this line. */
> 
>  // add user code here if he wants...
> 
> }
> //****************************** MAIN PROBLEM
> *****************************************
> 
> Now consider a class file in which some method x takes arguments as
> Frames object....
> then how i shuold call that methods which resides in that class ?
>  do i have to wrap that library class ?  if yes how ?what will be the
> structure of that wrapper ?
> 
> Any Links , s/w , pdf  which can help me to solve problem are most welcome.

I don't actually understand the problem.  The invocation API is quite
well-defined and allows you to call any Java method.  If you need to
pass a Java object to a Java method you'll have to call AllocObject
to create one, and if that's to be available as a C++ class you'll
have to generate a C++ wrapper.

Andrew.