Re: JNI Problems with MINGW32

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <>
Sun, 03 Aug 2008 16:01:53 -0400
<48960eae$0$90269$> wrote:

I'm trying to compile a DLL with MINGW32 for JNI. I keep getting
UnsatisfiedLinkErrors whenever I try running the class. It works fine
MS VC compiler from the .NET 1.1 SDK. If someone can tell me the
(probably obvious) thing I'm doing wrong, I'd be very grateful.

I'm using two different versions of my Makefile to link it. One using
ld, one doing it through gcc...

Here is the Java class from

class tst
    public native void c_tst();

    public static void main(String args[])
        tst x = new tst();

Here is the C code from tst.c:

#include "tst.h"
JNIEXPORT void JNICALL Java_tst_c_1tst(JNIEnv *env, jobject obj)

Here is the output from my Makefile:

javah -jni tst
gcc -g3 -Q -c -otst.o tst.c
 getc putc getchar putchar fopen64 ftello64 vsnwprintf Java_tst_c_1tst
Execution times (seconds)
 lexical analysis : 0.02 (35%) usr 0 kb ( 0%)
 symout : 0.01 (33%) usr 346 kb (21%)
 TOTAL : 0.05 1616 kb
dlltool -e exports.o --dllname tst tst.o
dlltool -l tst.a --dllname tst tst.o
ld -format pei-i386 -shared --dynamic-list-data --dll --add-stdcall-
alias --export-all-symbols --output-def tst.def -L/mingw/lib -l crtdll
-otst.dll tst.o exports.o

Here is the output from the JVM:

java.lang.UnsatisfiedLinkError: C:\MSYS\home\Administrator\java
\tst.dll: A dynamic link library (DLL) initialization routine failed
    at java.lang.ClassLoader$NativeLibrary.load(Native Method)
    at java.lang.ClassLoader.loadLibrary0(Unknown Source)
    at java.lang.ClassLoader.loadLibrary(Unknown Source)
    at java.lang.ClassLoader.loadLibrary0(Unknown Source)
    at java.lang.System.loadLibrary(Unknown Source)
    at tst.<clinit>(
Exception in thread "main"

The only difference between the two Makefiles is instead of ld --
format .... becomes:
gcc -g3 -Q -shared -otst.dll tst.o exports.o

When I use that, the JVM outputs

Exception in thread "main" java.lang.UnsatisfiedLinkError: c_tst
    at tst.c_tst(Native Method)
    at tst.main(

As I said earlier, I'm probably doing something obviously wrong, so
any suggestions would help.

I use:

gcc -c -I\myjava\include -I\myjava\include\win32 mypack_MyClass.c -o
gcc -s -shared -Wl,--export-all,--kill-at mypack_MyClass.obj -o mylib.dll


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