I am working on a Java project in which I have to use a third party dll (let's say abc.dll). So I created a native header file using JNI.
Then I created a dll project on vs2005 (typical win32 app.) and added that header file created by JNI. I selected clr old syntax support for the project and added the abc.dll as a reference to my project.
Up to now, everything is ok. Here is the problem. I implemented the methods defined in the header file using some methods from the abc.dll. abc.dll has a class called "abc" and that's what I do:
abc *abcObj = new abc(); abcObj->callSomeMethod();
I take a build from the solution, everything is ok. But when I run my Java program, I get an error from the JVM telling that native code broke down?!?! I debugged it and the problem is in new(). It simply cannot instantiate the abcObj.
Then I tried with a c++ app using that abc.dll. It worked.
I think there must be problem with JNI or that managed/unmanaged thing. I am not really experienced at c/c++ so I don't understand so much (at least I don't have time to understand for now). Only thing I try to do is create a wrapper dll using the third party dll and use the wrapper dll in my java app.
Any help will be appreciated.
Thanks in advance...
-haydar
edit: I have all the dlls that are needed by my third party dll.
I have solved the problem. The problem was that I was creating the project as a win32 application and choosing dll then. I created a clr application and everything went well. I followed the instructions from here.
Related
I have been working on creating a simple Java desktop app using the RESTful API for Business Objects and have run into an issue. Whenever I run my app in Eclipse in works fine; whenever I export it as a 'Runnable Jar' and select the Library handling option 'Package required libraries into generated JAR' it works fine. However, whenever I try to export it using the Library handling option 'Extract required libraries into generated JAR' I get the following error after running the app:
java.lang.NoClassDefFoundError: Could not initialize class com.businessobjects.bcm.BCM
I have the 'bcm.jar' file added under a 'res' Source Folder and have it added to the Build Path. At one point I added all the JARs under the 'SAP BusinessObjects' java folder, and external folder, but it still throws the error. The problem stems from this line of code:
enterpriseSession = CrystalEnterprise.getSessionMgr().logon(userID, password, CMS, auth);
Would anyone know why I am getting said error? I really want to use the Extract option as it will improve performance as my app becomes larger. Any help resolving this issue would be greatly appreciated :)
EDIT: I would be happy to provide clarification or further detail upon request!
Seems this was introduced in SP04 and SAP has no intent of fixing it as the RESTful API wasn't designed to be used with Desktop apps.
Have you included the cryptojFIPS.jar? Leaving it out can cause the error.
I am trying to deploy my application that invokes native calls using JNA library, but I get the following exception.
Exception in thread "main" java.lang.UnsatisfiedLinkError: Unable to load library 'myCustomDLL': Native library (win32-x86-64/myCustomDLL.dll) not found in resource path ([myproject/target/classes/, ...some jars...])
What do I need to do in order to invoke the function correctly?
Any help much appreciated
You must put your dll library (with native code) on application java.library.path.
See :
http://examples.javacodegeeks.com/java-basics/java-library-path-what-is-it-and-how-to-use/
Edit:
Post your project layout here. And how you run your app.
Check whether the DLL is executable.
Check the dependant DLLs are all executable.
With windows explorer, right click on DLL -> property -> security and verify execution rights.
Actually I found the answer to this. Basically, I needed to install Microsoft Visual C++ Redistributable package to install all the necessary DLLs needed for JNA to work. Thanks for other responses to this question.
I'm working with some java code wich loads an unmanaged dll, just as the following:
public void Foo(){
System.loadLibrary("absolute_path_to_my_dll.dll")
}
It works fine from eclipse or console.
Next step: I'm using IKVM tools to get a managed dll from my java app (ikvmc.exe). Everything works fine and my dll is built perfectly. In fact, I've imported that library in a Test Solution (and I've add all IKVM refereces needed -IKVM.Core.JDK, IKVM.Runtime.JNI, etc-).
Well, here is the problem: when I run C# code the java call to System.loadLibrary(...) fails and I get an "UnsatisfiedLinkError: Can't load absolute_path_to_my_dll.dll". Absolute path is ok and dll is there.
Any help? Thanks in advance.
Edit 1
I'll try to explain more in detail:
Java step
public void Foo(){
System.loadLibrary("absolute_path_to_my_dll.dll")
}
If path is not correct this call gives the "UnsatisfiedLinkError" mentioned above. This is not the case, everything works well. The dll file is a 32 bit one, so I compiled this java project with jre7 x86 (in 64 bit mode loadLibrary call falis, obviously, saying we can't load 32 bit dll in 64 bit AMD machine).
Ikvm step
Now I compile java code in a managed dll wich can be imported in a .net project. First of all I export my java project to a jar file, "myJar.jar". Then i apply ikvmc.exe to generate a managed dll, let's say "myNewDll.dll".
ikvm.exe -target:library -out:"myNewDll.dll" "myJar.jar"
This step works nicely and i get a new dll I can import in my VS project.
C# step
Now I create a new VS tester solution. I add "myNewDll.dll" as reference so I can use it in my C# code. Also, I add IKVM.Core.JDK reference (if not, project can't compile) and configure project in 32 bit mode. Problems start here:
Running this setup gives "IKVM.Runtime.JNI error". I've added that reference.
Running again gives "can't find ikvm-native". As I can't add ikvm-native-win32-x86.dll or ikvm-native-win32-x64.dll as reference I put both of them in output path (bin/Debug).
Next try it gives the "UnsatisfiedLinkError: Can't load xxx.dll".
How can it be possible if that dll is loaded flawlessly in java step?
Annother try
Just before start crying I tried annother way: I created a java main program that only called Foo(). Then I generated an executable file with ikvmc.exe tool and called it in windows console. It gave me the same error, UnsatisfiedLinkError so maybe it's ikvmc.exe problem but I can't understand why.
Any idea?
Edit 2
Good news. It seems I've solved the problem. First of all, I had to add -platform:x86 to ikvmc.exe call (step 2). The dll generated was succesfully imported in my C# project and it works fine if we run in execution mode (NOT debugging). If I try to debug in VS it gives me System.Runtime.InteropServices.SEHException.
Is there any kind of bug related to debugging native code (dll loaded in java code) under native code (that java code loaded in C# using ikvm)?
Is your dll a 32 bit and you run it on a 64 bit platform?
If yes then the problem is that IKVM is platform independent. This means on a 64 bit system it runs 64 bit process.
To solve this you need a 64 bit version of your dll or mark ikvm.exe as 32 bit process.
Adding an option of reference to IKVM.OpenJDK.Core.dll at ikvm's /bin directory will resolve the error.
Maybe the .jar file needs some native DLLs, which was same as Native library location parameter of JAR in Eclipse. If so, find the native DLLs and copy them to de /bin directory of IKVM, and make ikvmc to load them automatically.
That's all what I've found out. Try and see if it would bring some ideas.
Update: The problem was solved with the help of MathWorks. I've published the answer below.
I need to control a program (Zemax) from Matlab. Unfortunately, Zemax only supports DDE for such control, which Matlab does not support any more. It works, but stops working on 64 bit platform after a few (presumable 63) DDE calls.
I wonder if there are working solutions. I could probably program a DLL with correct DDE support and then use DDE in Matlab via this DLL. This is a major effort for me. A more suitable solution would be to use Java DDE methods. Following another post here, I've discovered the JDDE library. However I cannot make it work: Even if I am in the directory with the DLL and JAR files, executing
import pretty-tools.JDDE-2.0.3.*
works fine but calling
a = com.pretty_tools.dde.client.DDEClientConversation()
afterwards (as done here) results in
Undefined variable "com" or class "com.pretty_tools.dde.client.DDEClientConversation".
I have very limited writing privileges on my PC, so I have added the javaclasspath.txt file with the jar/dll location to the directory indicated by prefdir. The file looks like this:
C:\Users\xxxxxxxx\Documents\matlab toolbox\jdde\pretty-tools-JDDE-2.0.3.jar
Calling javaclasspath shows a long listing with the last lines being:
...
C:\Program Files\MATLAB\R2012b\java\jarext\webservices\ws_client_core\mw-service-client-core.jar
C:\Users\kkarapet\Documents\matlab toolbox\jdde\pretty-tools-JDDE-2.0.3.jar
DYNAMIC JAVA PATH
<empty>
So path seems to be set correctly. What am I doing wrong?
With the help of MathWorks support, I've found the answer. Here is how to make JDDE work with Matlab 2012b, without admin privileges:
Download and unpack JDDE files (DLLs and JAR) into some folder. Let's say it's $path-to-jdde$\.
In Matlab, type prefdir. Open the resulting directory and create two files there, javaclasspath.txt and javalibrarypath.txt.
In javaclasspath.txt, add $path-to-jdde$\pretty-tools-JDDE-2.0.3.jar.
In javalibrarypath.txt, add $path-to-jdde$\.
Restart Matlab.
Now call ddeConv = com.pretty_tools.dde.client.DDEClientConversation; and start using the created object as described in JavaDoc. E.g. to connect to Zemax, run Zemax and then in call ddeConv.connect('Zemax', 'abc').
Step 2 above can only be done starting Matlab version R2012b. With an older version, if you have the write rights on the Matlab installation directory, you should be able to replace step 2 by editing the files librarypath.txt and classpath.txt in $MATLABROOT$\toolbox\local. I could not verify it so if you confirm it please let me know in the comment below.
I am working on a team project in Java. One requirement is that we dynamically populate a drop-down menu of all classes that implement a certain interface. New classes can be added after compile time. To accomplish this we are using reflection.
Problem: All of the drop-down menus are blank on my system. I cannot for the life of me figure out why they are not populating. All other 5 team members have it working on their system.
Things I tired that didn't work:
1) Installing most recent eclipse (galileo) because rest team was using it
2) Re-install most recent java release (jdk1.6.0-17 and jre6)
3) Check PATH and JAVA_HOME variables
Any thoughts as to what else I can try or if something I did should have solved it and didn't? It is driving me crazy.
Edit:
I should have been clearer that we are developing in a team. We are using SVN for version control and we are all running the exact same source code. I even tried checking out a fresh copy of the entire tree from SVN, but I had the same issue with reflection on my system while it worked for teammates.
The team created an executable jar and that ran on everyone's system fine except for mine. Everything worked for me except the reflection bit.
You need to debug your application. This means you have to systematically explore possible causes of the problem. Here are some things that come to mind:
Could your GUI be failing rather than reflection? What if you output with System.out.println() rather than your menu?
Is your reflection code throwing an exception, and are you ignoring it?
Is your reflection code actually being called? Toss a println() in there to be sure!
Is the test for the interface suffering from a typo or similar error that's causing it to fail? Try finding classes that implement Serializable instead!
Is your reflection test running in the main thread and trying to update your GUI? You need to use SwingUtilities.invokeAndWait to get an update to the Swing worker thread.
You're working with Eclipse; Eclipse has a fantastic debugger. Set a breakpoint near where your main action is and then single step through the code.
PATH and JAVA_HOME won't help. PATH only affects dynamically-linked libraries ("native code"). JAVA_HOME is a scripting variable that happens to be used by some Java-based utilities like Ant and Tomcat; it means nothing to the Java runtime itself.
You need to be investigating the classpath, which should be specified by the -classpath option to the java command, in the Build Path in your Eclipse project properties, or in the Class-Path attribute of the main section of a JAR file if you're launching java with the -jar option.
From within your code, you should be able to list the contents of your classpath by examining the system property, "java.class.path"
System.out.println(System.getProperty("java.class.path"));
Problem solution:
Classpath leading to source code must have no spaces in it.
I am running windows XP and, for whatever reason, if the classpath that leads to the jar file or source code that is using reflection has any spaces in it, then the reflection fails.
I took the jar file that works for the rest of my team and ran it from C:\ on my system and the reflection worked perfectly fine.
I do not know why this is so please comment if you know what is happening.
Might be a long shot, but look for differences in security settings for you and your team mates. Article describing more details http://www.ibm.com/developerworks/library/j-dyn0603/ heading "Security and reflection"