This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It's not neccessary that a Visual Basic DLL is going to be a COM object. If the Visual basic DLL is a COM object, then you can use JACOB or other Java-COM bridges to call the DLL. If it's not, then you will have to develop your own C++ JNI layer that will wrap the Visual basic DLL and export the functions to Java