JNA -> VB COM VARIANT Array of one element?

[Jared Davis]

Hi,

I think I need to create a VARIANT that is an array of 1 integer to match the VB class below.

    /**

     * <p>id(0x60030030)</p>

     * <p>vtableId(59)</p>

     * @param lNumberOfProjects [inout] {@code Integer}

     * @param sPdsg [in, optional] {@code String}

     */

    @ComMethod(name = "ProjectCount", dispId = 0x60030030)

    eProjectReturnCode ProjectCount(VARIANT lNumberOfProjects, String sPdsg);

VB6 Declaration is this:

Public Function ProjectCount(lNumberOfProjects As Long, _

    Optional ByVal sPdsg As String) As eProjectReturnCode

The function alters the INumberOfProjects value and that is the data I need in Java.

One of the issues I have is the INumberOfProjects variable is never updated in java after a call.

from here:

https://docs.oracle.com/cd/E13222_01/wls/docs61/jcomreference/SupportedActiveXdatatypes.html

It looks like I need to pass

a java.lang.Integer[] single element array

as the first parameter.

I can not figure out how to do it.

Thanks in advance.

Jared

[Jared Davis]

Here is what I have tried:

A test DLL com control was created using the same vb6 compiler so I can share the DLL if anyone wants to try.

COM control does some debugmessage outputs and adds 10 to the passed in number. That is it.

Full vb6 source:

 

Option Explicit

 

Public Enum eProjectReturnCode

    RETURN_ERROR = 0

    RETURN_OK = -1

    RETURN_USER_CANCEL = -2

End Enum

 

Private Declare Sub OutputDebugString Lib "kernel32" Alias "OutputDebugStringA" (ByVal lpOutputString As String)

 

Public Function ProjectCountTest(lNumberOfProjects As Long, Optional ByVal sPdsg As String) As eProjectReturnCode

     OutputDebugString "ProjectCountTest start" + Chr(13) + Chr(10)

     OutputDebugString "ProjectCountTest passed in long " + Str(lNumberOfProjects) + Chr(13) + Chr(10)

     OutputDebugString "ProjectCountTest passed in string [" + sPdsg + "]" + Chr(13) + Chr(10)

    lNumberOfProjects = lNumberOfProjects + 10

     OutputDebugString "ProjectCountTest returning " + Str(lNumberOfProjects) + Chr(13) + Chr(10)

 

  ProjectCountTest = RETURN_OK

  OutputDebugString "ProjectCountTest setting return to OK, may change" + Chr(13) + Chr(10)

 

  If (Len(sPdsg)) > 0 Then

     If sPdsg = "AER" Then

         ProjectCountTest = RETURN_ERROR

       OutputDebugString "ProjectCountTest setting return_error" + Chr(13) + Chr(10)

     ElseIf sPdsg = "BUC" Then

      ProjectCountTest = RETURN_USER_CANCEL

       OutputDebugString "ProjectCountTest setting return_user_cancel" + Chr(13) + Chr(10)

    End If

   End If

 End Function

generated java classes

@ComObject(clsId = "{5D1B16BD-41DD-47B1-9D2C-21627949AE7D}")

public interface COMTester extends IUnknown

    ,_COMTester

{

}

@ComInterface(iid="{C4B5FC56-593D-4935-B7E2-C9B3B05F2541}")

public interface _COMTester extends IUnknown, IRawDispatchHandle, IDispatch {

    /**

     * <p>id(0x60030000)</p>

     * <p>vtableId(7)</p>

     * @param lNumberOfProjects [inout] {@code Integer}

     * @param sPdsg [in, optional] {@code String}

     */

    @ComMethod(name = "ProjectCountTest", dispId = 0x60030000)

    eProjectReturnCode ProjectCountTest(VARIANT lNumberOfProjects,

            String sPdsg);

            

    

}

Send in 1 expect 11 back for the vb LONG java int variable. Never get 11 back.

public class ComTest001 {

    public static void main(String[] args) throws IOException {

        WinNT.HRESULT hr = Ole32.INSTANCE.CoInitializeEx(Pointer.NULL, Ole32.COINIT_APARTMENTTHREADED); 

        COMUtils.checkRC(hr);

        Factory fact = new Factory();

        try {

            System.out.println("A");

            COMTester comtest = fact.createObject(COMTester.class);

            System.out.println("B");

            int one = 1;

            

            //IntByReference length = new IntByReference(one);

            //VARIANT vp = new VARIANT(length);

              //C int@0x5d7dc0=0x1 (1)

              //Exception in thread "main" com.sun.jna.platform.win32.COM.COMInvokeException: Type mismatch.(HRESULT: 80020005) (puArgErr=1)

            

            //VARIANT vp = new VARIANT(one);

               // runs but vp does not contain value set in com method.

            

            

            

            //IntByReference length = new IntByReference(one);

            //VARIANT.ByReference vp = new VARIANT.ByReference(length.getPointer());

            //Exception in thread "main" java.lang.IllegalArgumentException: Structure exceeds provided memory bounds

    //at com.sun.jna.Structure.useMemory(Structure.java:372)

     //.. Caused by: java.lang.IndexOutOfBoundsException: Bounds exceeds available space : size=4, offset=16

         //   VARIANT v = new VARIANT(one);

         //   VARIANT.ByReference vp = new VARIANT.ByReference(v.getPointer());

         // runs but vp / v do not contain value set in com method.

            

            

            

            //VARIANT v = new VARIANT(one);

            //VARIANT.ByReference vp = new VARIANT.ByReference(v);

            // runs but vp / v do not contain value set in com method.

            

            

            VARIANT v = new VARIANT(one);

            VARIANT vp = new VARIANT(v.getPointer());

            // runs but vp / v do not contain value set in com method.

            

            System.out.println("C  " + vp.getValue());

            eProjectReturnCode rc = comtest.ProjectCountTest(vp, "");

            System.out.println("D  " + rc);

            System.out.println("E  " + vp.getValue());

            System.out.println("EE " + v.getValue());

        } finally {

            fact.disposeAll();

            Ole32.INSTANCE.CoUninitialize();

        }

    }

output

A

B

C  1

D  RETURN_OK

E  1

EE 1

E/ EE should be 11 for a valid run.

debugmessages

[8896] ProjectCountTest start 

[8896] ProjectCountTest passed in long  1 

[8896] ProjectCountTest passed in string [] 

[8896] ProjectCountTest returning  11 

[8896] ProjectCountTest setting return to OK, may change 

[Matthias Bläsing]

Hi Jared,

this is a gut feeling, as I have no experience with interfacing with
VB, but Variants are a huge beast and you can not only store value, but
also references to values.

The binding of VARIANT is a bit arkward and maybe I'd have bound it
differently, but that is history.

I suggest to do this:

VARIANT variant = new VARIANT();
LONGLONGByReference longHolder = new LONGLONGByReference();
longHolder.setValue(new LONGLONG(42L));
variant.setValue(Variant.VT_I8 | Variant.VT_BYREF, longHolder);
// Call your code
long result = longHolder.getValue().longValue();

Or (unsigned variant):

VARIANT variant = new VARIANT();
ULONGLONGByReference longHolder = new ULONGLONGByReference();
longHolder.setValue(new ULONGLONG(42L));
variant.setValue(Variant.VT_UI8 | Variant.VT_BYREF, longHolder);
// Call your code
long result = longHolder.getValue().longValue();

The idea is here, that you pass only the reference with a type
signature through the variant.

This is untested and if kittens die, I don't feel responsible.

Greetings

Matthais

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[Jared Davis]

Hi,

Thanks.

No kittens harmed, at this time. But exceptions were thrown.

C  LONGLONG@0x12b82e0=42

Exception in thread "main" com.sun.jna.platform.win32.COM.COMInvokeException: Type mismatch.(HRESULT: 80020005) (puArgErr=1)

LONG in vb is an int in java. So I need INTINT. Don’t see one.

DWORD was closest. There is no DWORDDWORDByReference class, yet. I tried to write one. source below.

I think I need a VT_I4 type.

I am probably wrong on the unsigned vs signed issues in DWORD vs int. Don't care at this point. 

            VARIANT v = new VARIANT();

            DWORDDWORDByReference holder = new DWORDDWORDByReference();

            holder.setValue(new DWORDDWORD(42L));

            v.setValue(Variant.VT_I4 | Variant.VT_BYREF, holder);

New interface/classes below throw an error. Stumped again.

 

Throws

Exception in thread "main" java.lang.IllegalArgumentException: Can not set com.sun.jna.platform.win32.WinDef$LONGByReference field com.sun.jna.platform.win32.Variant$VARIANT$_VARIANT$__VARIANT.plVal to jnatest.WinDefExtended$DWORDDWORDByReference

at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)

at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)

at sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)

at java.lang.reflect.Field.set(Field.java:758)

at com.sun.jna.Structure.setFieldValue(Structure.java:668)

at com.sun.jna.Structure.setFieldValue(Structure.java:662)

at com.sun.jna.Structure.writeField(Structure.java:837)

at com.sun.jna.Union.writeField(Union.java:143)

at com.sun.jna.platform.win32.Variant$VARIANT.setValue(Variant.java:386)

at com.sun.jna.platform.win32.Variant$VARIANT.setValue(Variant.java:326)

at jnatest.ComTest001.main(ComTest001.java:78)

ComTest001.java:78 is this line:    v.setValue(Variant.VT_I4 | Variant.VT_BYREF, holder);

package jnatest;

import com.sun.jna.IntegerType;

import com.sun.jna.platform.win32.WinDef;

import com.sun.jna.ptr.ByReference;

public interface WinDefExtended  extends WinDef {

    

     public static class DWORDDWORD extends IntegerType implements Comparable<DWORDDWORD> {

        public static final int SIZE = 4; // WORD =2, DWORD =4

        public DWORDDWORD() {

            this(0);

        }

        public DWORDDWORD(long value) {

            super(SIZE, value, false);

        }

        @Override

        public int compareTo(DWORDDWORD other) {

            return compare(this, other);

        }

    }

    public class DWORDDWORDByReference extends ByReference {

        public DWORDDWORDByReference() {

            this(new DWORDDWORD(0));

        }

        public DWORDDWORDByReference(DWORDDWORD value) {

            super(DWORDDWORD.SIZE);

            setValue(value);

        }

        public void setValue(DWORDDWORD value) {

            getPointer().setInt(0, value.intValue());

        }

        public DWORDDWORD getValue() {

            return new DWORDDWORD(getPointer().getInt(0));

        }

    }

}

[Jared Davis]

Hi,

Please ignore the prior message I posted. I was very very wrong. Your reply led me to a solution.

            VARIANT v = new VARIANT();

            LONGByReference longHolder = new LONGByReference(new LONG(42));

            v.setValue(Variant.VT_I4 | Variant.VT_BYREF, longHolder);

            

            System.out.println("C " + v.getValue());

            eProjectReturnCode rc = comtest.ProjectCountTest(v, "");

            System.out.println("D  " + rc);

            System.out.println("EE " + v.getValue());

[4584] ProjectCountTest start 

[4584] ProjectCountTest passed in long  42 

[4584] ProjectCountTest passed in string [] 

[4584] ProjectCountTest returning  52 

[4584] ProjectCountTest setting return to OK, may change 

C LONG@0x916100=42

D  RETURN_OK

EE LONG@0x916100=52

EE is now 52!!!

Thanks!