Java call C Dll

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I need to call a function that is there in a C++ dll. The arguments to the function are STRUCT and string. The return type is void. Also I donot have any rights to change the dll and I have to use as it is.... So here goes my questions: 1. How to pass a struct variable from Java to a function in DLL. 2. The function returns void and the second argument is the output variable which I need to use. So is there anyway, that call by reference can be used from Java? 3. Where should I place my dll to compile it? Quick reply would be appreicated. Thanks in advance. Samagna Samagna

Samagna

09-07-2004, 12:55 PM	#2
Chris Uppal  Posts: n/a	Re: Calling a C++ dll from Java Samagna wrote: > I need to call a function that is there in a C++ dll. The arguments to > the function are STRUCT and string. You can't, I'm afraid. Java does not have the ability to call arbitrary code from an arbitrary DLL, nor does it understand 'structs'. So you have to be a bit more indirect. What you will have to do is write your own C or C++ code which follows the JNI conventions, and which therefore /can/ be called from Java, and then call the other DLL from that. The Sun JNI tutorial at: http://java.sun.com/docs/books/tutor...1.1/index.html should get you started on JNI programming. It's not difficult if you keep it simple, and it doesn't sound as if you need to do anything very complicated for these purposes. -- chris Chris Uppal

Chris Uppal

09-07-2004, 04:19 PM	#3
Tor Iver Wilhelmsen  Posts: n/a	Re: Calling a C++ dll from Java (Samagna) writes: > I need to call a function that is there in a C++ dll. The arguments to > the function are STRUCT and string. The return type is void. Also I > donot have any rights to change the dll and I have to use as it is.... You need to make an intermediate layer in JNI that convert Java arguments into the necessary C++ arguments. Since Java does not have "out" parameters, you need to use a return value of some sort from your Java native method. Tor Iver Wilhelmsen

Tor Iver Wilhelmsen

09-08-2004, 01:23 PM	#4
Stian Bakken  Posts: n/a	Re: Calling a C++ dll from Java There are commercial software that will wrap .dll's for you. Here are two: http://www.excelsior-usa.com/xfunction.html http://www.jniwrapper.com/index.jsp Disclaimer: I have not tried any of these, but they might suit your needs. Good luck, Stian "Samagna" <> wrote in message news: om... > I need to call a function that is there in a C++ dll. The arguments to > the function are STRUCT and string. The return type is void. Also I > donot have any rights to change the dll and I have to use as it is.... > So here goes my questions: 1. How to pass a struct variable from Java > to a function in DLL. 2. The function returns void and the second > argument is the output variable which I need to use. So is there > anyway, that call by reference can be used from Java? 3. Where should > I place my dll to compile it? > > Quick reply would be appreicated. > Thanks in advance. > Samagna Stian Bakken

Stian Bakken

12-19-2004, 11:35 PM	#5
Robert kebernet Cooper  Posts: n/a	Re: Calling a C++ dll from Java Depending on what you are trying to do, the IBM Java-COM bridge can be a MUCH MUCH easier way of moving data between the two than hand building JNI stuff. I have used this with Microsoft MapPoint and some other MS-ish API's quite successfully. http://www-106.ibm.com/developerwork...y/j-intbridge/ Robert kebernet Cooper

Robert kebernet Cooper

12-20-2004, 11:48 PM

#6

Tilman Bohn  Posts: n/a

Re: Calling a C++ dll from Java [f'up2 cljp] In message < .com>, Robert kebernet Cooper wrote on 19 Dec 2004 15:35:19 -0800: [...] > http://www-106.ibm.com/developerwork...y/j-intbridge/ This looks very interesting, I hadn't known about that! Could come in very handy indeed in an upcoming project, so thanks from me for that pointer! -- Cheers, Tilman `Boy, life takes a long time to live...' -- Steven Wright Tilman Bohn