java-dev

Matthew,

Check that your headers and C functions are correct. Run 'javah' on  
the class that defines the native method calls to get what Java is  
looking for.

Michael

On 14 May 2008, at 20:46, Matthew Grivich wrote:

> Hello All,
>
>  I am attempting to write a frame grabber and camera control program
> for Macintosh.  The frame grabber in question uses a C api.  I have
> written a simple java wrapper for this using the java native interface
> (JNI), entirely in Xcode.  However, Xcode does not have very good Java
> support, so I'd like to write the Java portions of the program in
> Eclipse, and the C and java native interface portions in Xcode.  I am
> using Xcode 3.0, OS 10.5.2, a dual processor G5, and Eclipse 3.3.2.
>
> First, I will say what works.  In Xcode: File -> New Project -> Java  
> ->
> Java JNI Application.  Makes jni version of hello world, works  
> fine.  I
> copy the generated headers folder and the .jnilib to a jnilib folder  
> in
> my eclipse project (EclipseTest/jnilib).  In eclipse: Right click
> project name (EclipseTest) -> properties -> source -> EclipseTest/ 
> src ->
> Set Native library location to EclipseTest/jnilib.  I copy the .java
> file from the Xcode project to the Eclipse Project src folder, by
> creating a new java file in Eclipse, and copy-pasting the text of the
> file from Xcode.  Everything works.
>
> In Xcode:  I start with the jni hello world.  I add the C files from  
> the
> third party api.  I write the appropriate wrapper code to do some  
> simple
> operations with the camera (open, snap, and close) from java.  In  
> order
> to get things to link properly, I add a build phase to the JNILib
> target.  This build phase is Link Binary With Libraries.  Right click
> this, then Add -> Existing Frameworks -> select the five necessary  
> third
> party frameworks.  These frameworks are located in /Library/ 
> Frameworks.
> This all works.
>
>
> Now, I will get to what doesn't work.  I transfer camera .jnilib and
> headers folder over to an eclipse project.  When I try to run it, I  
> get
>
> Started application
> Exception in thread "main" java.lang.UnsatisfiedLinkError: OpenCamera
>   at edu.salk.snl.micrimap.Grabber.OpenCamera(Native Method)
>   at edu.salk.snl.micrimap.Grabber.main(Grabber.java:80)
>
> When I don't make the jnilib available, it gives
>
> Exception in thread "main" java.lang.UnsatisfiedLinkError: no  
> Grabber in
> java.library.path
>   at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1753)
>   at java.lang.Runtime.loadLibrary0(Runtime.java:822)
>   at java.lang.System.loadLibrary(System.java:993)
>   at edu.salk.snl.micrimap.Grabber.<clinit>(Grabber.java:25)
>
> So I know that it is finding the .jnilib.
>
> My belief is that it is not finding the third party frameworks.
> However, I have not found the "make it work" button.  Any assistance
> would be much appreciated.
>
> Thanks.
>
> Matthew
>
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