从Java调用VB.net函数

Question

如何在Java中调用VB.net函数？我尝试用Java做这个：

import java.util.HashMap;
import java.util.Map;

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.win32.StdCallFunctionMapper;
import com.sun.jna.win32.StdCallLibrary;

public class Main2{
public interface Class1 extends StdCallLibrary
{
    void fn_Today(int a,int b);
}

public static void main(String[] args)
{
    Map options = new HashMap();
        options.put(Library.OPTION_FUNCTION_MAPPER, new StdCallFunctionMapper()) ;
        Class1 INSTANCE = (Class1) Native.loadLibrary("fn_Today", Class1.class, options);
    INSTANCE.fn_Today(0, 0);
}

}

但它返回了这个： enter image description here

VB.Net中的我的代码：

Public Class TestClass
Public Function SumNum(Val1 As Integer, Val2 As Integer)
    Dim TVal As Integer
    TVal = Val1 + Val2

    Return TVal

End Function
End Class