JNI Phun.....

[ian maclure]

I'm trying to understand JNI well enough to be be able to supply
a state model class in C++ to some client applications and use the
same model in the JAVA app that controls the clients.
The state model class is written.
I thought a good place to start might be with the JAVA JNI Tutorial
HelloWorld instance, so I set up HelloWorld.java , compiled it, ran it
through javah, setup the HelloWorldImp.c ( native C language method )
and compiled it per the instructions ( or what the instructions implied ):

got HelloWorld.java
java HelloWorld.java
javah -jni HelloWorld
checked HelloWorld.h
got HelloWorldImp.c

Set LD_LIBRARY_PATH to the PWD since thats where everything resides

compiled HelloWorldImp.c as follow:

ZZZZ=HelloWorld Imp.c
JJJJ=/usr/java/sdk ( 1.4.2_01 as it happens )
CPPOPT="-c -g -shared"
gcc $CPPOPT -I$JJJJ/include -I$JJJJ/include/linux $ZZZZ -o libhello.so


I am running on a RedHat 9 Linux box by the way.

Got the resulting libhello.so and then tried to run the app

java HelloWorld

What I got was:

Exception in thread "main" java.lang.Unsat isfiedLinkError : \
<obfuscated>/JNI_d/libhello.so: \
<obfuscated>/JNI_d/libhello.so: \
ELF file's phentsize not the expected size
at java.lang.Class Loader$NativeLi brary.load(Nati ve Method)
at java.lang.Class Loader.loadLibr ary0(ClassLoade r.java:1560)
at java.lang.Class Loader.loadLibr ary(ClassLoader .java:1485)
at java.lang.Runti me.loadLibrary0 (Runtime.java:7 88)
at java.lang.Syste m.loadLibrary(S ystem.java:834)
at HelloWorld.<cli nit>(HelloWorld .java:15)

No idea what this means although I suspect it has something to do with the
compilation of HelloWorldImp.c .
What have I done ( or not ) as the case may be.

Thanx.....

IBM





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[ian maclure]

Re: JNI Phun.....

On Fri, 26 Mar 2004 23:25:43 +0000, ian maclure wrote:
[color=blue]
>
> I'm trying to understand JNI well enough to be be able to supply
> a state model class in C++ to some client applications and use the
> same model in the JAVA app that controls the clients.[/color]

[snip]
[color=blue]
> ZZZZ=HelloWorld Imp.c
> JJJJ=/usr/java/sdk ( 1.4.2_01 as it happens )
> CPPOPT="-c -g -shared"
> gcc $CPPOPT -I$JJJJ/include -I$JJJJ/include/linux $ZZZZ -o libhello.so[/color]

Problem was the "-c" in CPPOPT. Just run the preceding with
CPPOPT=shared and things work.

IBM

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[Roman]

Re: JNI Phun.....

You might want to include -fPic flag as well if you want position
independent code.

"ian maclure" <ibm@svpal.or g> wrote in message
news:pan.2004.0 3.29.17.05.20.4 66711@svpal.org ...[color=blue]
> On Fri, 26 Mar 2004 23:25:43 +0000, ian maclure wrote:
>[color=green]
> >
> > I'm trying to understand JNI well enough to be be able to supply
> > a state model class in C++ to some client applications and use the
> > same model in the JAVA app that controls the clients.[/color]
>
> [snip]
>[color=green]
> > ZZZZ=HelloWorld Imp.c
> > JJJJ=/usr/java/sdk ( 1.4.2_01 as it happens )
> > CPPOPT="-c -g -shared"
> > gcc $CPPOPT -I$JJJJ/include -I$JJJJ/include/linux $ZZZZ -o[/color][/color]
libhello.so[color=blue]
>
> Problem was the "-c" in CPPOPT. Just run the preceding with
> CPPOPT=shared and things work.
>
> IBM
>
>[/color]
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___[color=blue]
> Posted Via Uncensored-News.Com - Accounts Starting At $6.95 -[/color]
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