Calling SWT from C++ code

Fri Nov 5 10:32:00 GMT 2004

Hi All,

      Is it possible to call SWT class in java from C++ using CNI,

What i want to do

1. Write a class in JAVA that uses SWT to draw a screen -- This i have done
and work fine
2. Create a CNI header for this .java file and include in my C++ class, and
try to access the java class methods
3. Compile it using g++ -- compilation fails

my java class

[Phone.java]

import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.SWT;
/*
 * Created on Nov 2, 2004
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**

 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class Phone extends Composite {

      private KeyPad Kpd = null;
      private MobileSimu pScr = null;

      public static void main(String[] args) {
            /* Before this is run, be sure to set up the following in the
launch configuration
             * (Arguments->VM Arguments) for the correct SWT library path.
             * The following is a windows example:
             * -Djava.library.path
="installation_directory\plugins\org.eclipse.swt.win32_3.0.0\os\win32\x86"
             */

            org.eclipse.swt.widgets.Display display =
org.eclipse.swt.widgets.Display.getDefault();
            org.eclipse.swt.widgets.Shell shell = new
org.eclipse.swt.widgets.Shell(display);
            shell.setLayout(new org.eclipse.swt.layout.FillLayout());
            shell.setSize(new org.eclipse.swt.graphics.Point(185,570));
            Phone thisClass = new Phone(shell, org.eclipse.swt.SWT.NONE);
            shell.open();
            thisClass.setText(new String("Dummy"));

            while (!shell.isDisposed()) {
                  if (!display.readAndDispatch()) display.sleep ();
            }
            display.dispose();
      }

      public Phone(Composite parent, int style) {
            super(parent, style);
            initialize();
      }
      private void initialize() {

             Kpd = new KeyPad(this,SWT.NONE);
             pScr = new MobileSimu(this,SWT.NONE);

             this.setBackground(org.eclipse.swt.widgets.Display.getDefault
().getSystemColor(org.eclipse.swt.SWT.COLOR_GRAY));
             this.setBounds(new
org.eclipse.swt.graphics.Rectangle(0,0,200,460));

      }
      public void setText(String pString)
      {
            pScr.setText(pString);
      }

}

[Phone.h]

// DO NOT EDIT THIS FILE - it is machine generated -*- c++ -*-

#ifndef __Phone__
#define __Phone__

#pragma interface

#include <org/eclipse/swt/widgets/Composite.h>
#include <gcj/array.h>

extern "Java"
{
  class Phone;
  namespace org
  {
    namespace eclipse
    {
      namespace swt
      {
        namespace widgets
        {
          class Composite;
        }
      }
    }
  }
  class MobileSimu;
  class KeyPad;
}

class Phone : public ::org::eclipse::swt::widgets::Composite
{
public:
  static void main (JArray< ::java::lang::String *> *);
  Phone (::org::eclipse::swt::widgets::Composite *, jint);
private:
  void initialize ();
public:
  virtual void setText (::java::lang::String *);
private:
  ::KeyPad * __attribute__((aligned
(__alignof__( ::org::eclipse::swt::widgets::Composite )))) Kpd;
  ::MobileSimu *pScr;
public:

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

#endif /* __Phone__ */

[callJH.cpp]

// we want to use the CNI
#include <gcj/cni.h>
#include <gcj/array.h>

// we want to use some java classes
#include <java/lang/System.h>
#include <java/io/PrintStream.h>
#include "../MobileSimu/Phone.h"
#include <java/lang/Throwable.h>
#include <java/lang/reflect/Method.h>
#include <java/lang/reflect/Modifier.h>
#include <java/lang/reflect/Array.h>
#include <java/util/Hashtable.h>

 using namespace java::lang;

int main(void)
{
      JvCreateJavaVM( NULL);
      JvAttachCurrentThread( NULL, NULL);

      Phone* obj = new Phone();
      obj->setText(JvNewStringLatin1("from c++"));

    JvDetachCurrentThread();

}

i am compling this as

g++ -c callJH.cpp

errors i get are

C:\Documents and Settings\716185>d:

D:\>cd wsp

D:\wsp>ls
MobileSimu  Testing  callJava  jniTesting  tempC
Project     callJH   demo1     sampleJava

D:\wsp\callJH>g++ callJH.cpp
In file included from callJH.cpp:10:
../MobileSimu/Phone.h:8:47: org/eclipse/swt/widgets/Composite.h: No such
file or
 directory
In file included from callJH.cpp:10:
../MobileSimu/Phone.h:32: error: invalid use of undefined type `struct
org::ecli
pse::swt::widgets::Composite'
../MobileSimu/Phone.h:22: error: forward declaration of `struct
org::eclipse::sw
t::widgets::Composite'
../MobileSimu/Phone.h:41: error: invalid application of `__alignof__' to an
inco
mplete type
../MobileSimu/Phone.h:41: error: requested alignment is not a power of 2
callJH.cpp: In function `int main()':
callJH.cpp:25: error: no matching function for call to `Phone::Phone()'
../MobileSimu/Phone.h:35: note: candidates are:
Phone::Phone(org::eclipse::swt::
widgets::Composite*, jint)

Can somebody help

Thanks and Regards

Praful Bhoyar

Thanks and Regards

Praful Bhoyar
L&T Infotech
Navi Mumbai
0091-22-55934125

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