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Hey, so I'm a math student working on a computer program.
I've got to call some C methods from my java code so I'm working on learning some basic JNI(java native interface).
I am working on Fedora.
I'm putting together the very simple HelloWorld program for starters.
I'm following along exactly with the book.
Java code is written fine, C code is written fine.
Now I need to compile HelloWorld.c into libHelloWorld.so but the book only gives commands to do this for Solaris and Win32. I tried the Solaris command but it didn't work.
The command given is:
cc -G -I/java/include -I/java/include/solaris HelloWorld.c -o libHelloWorld.so
The message I get is:
cc: unrecognized option '-G'
HelloWorld.c:5: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
HelloWorld.c:8: error: stray ‘\’ in program
HelloWorld.c:8: error: missing terminating " character
If anyone has any idea of the proper command or what I'm doing wrong I'd appreaciate it, Thanks!
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type: man cc
and look up for an option that does what you want.
dunno really...
going to sleep now, but just by looking at your problem for a few secs, it appears you are trying to
access something on solaris (a sun OS which has good java support) on fedora, a typical linux machine.
try dig around sun forum and see if they have something that you can install.
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looks like your cc binary wasn't compiled with the proper flags. did you compile it from source or are you using a pre-built package?
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zdd:
Ok well I don't really understand what you just said, but I assume you're talking about my fedora setup? I didn't set up anything on this computer if that is what you are asking.
Sorry for my lack of knowledge heh, I'm not really a comp sci student.
haduken:
Thanks for the advice, I'll look into it ^^
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On May 16 2008 01:36 Zortch wrote:
zdd:
Ok well I don't really understand what you just said, but I assume you're talking about my fedora setup? I didn't set up anything on this computer if that is what you are asking.
Sorry for my lack of knowledge heh, I'm not really a comp sci student.
haduken:
Thanks for the advice, I'll look into it ^^
generally "unrecognized option" in the output means that the program does not support the function you are trying to make it perform, because someone explicitly specified it at compile time by not setting a "flag" to the compiler that made your "cc" program, or the function has a different parameter than the one you are used to. so the -G is not supported by your cc, and since you are probably using the pre-built fedora cc package, I would recommend rebuilding cc from the source code with the flag for whatever feature "-G" is enabled, or finding out if the feature has to be called with a different parameter other than -G.
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Canada9720 Posts
some very smart people i've worked with have told me that JNI is one the hardest APIs around to learn, so goodluck. I've only got minimal experience with it, so I'm not any help. sorry
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On May 16 2008 01:46 CTStalker wrote:
some very smart people i've worked with have told me that JNI is one the hardest APIs around to learn, so goodluck. I've only got minimal experience with it, so I'm not any help. sorry
JNI is nasty indeed. I won't even touch it.
Godspeed. Google, google, google.
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Yeap it's very hard because you make a mistake in your C code and you will get huge native stack trace that will kill your JVM.
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Heh, thanks guys.
The worst part is, JNI isn't even the problem...yet xD
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hi there, lemme try to shed some light on this.
first of all, unix (solaris) isnt linux (fedora). you can easily tell from the man pages for any unix command and their linux counterpart. that's not to say they are completely different, sometimes the differences are very subtle, even undocumented...
that said, ill copy/paste the man pages for solaris 5.9 (which i have) for the cc command
+ Show Spoiler +
SunOS/BSD Compatibility Package Commands cc(1B)
NAME
cc - C compiler
SYNOPSIS
/usr/ucb/cc [options]
DESCRIPTION
/usr/ucb/cc is the interface to the BSD Compatibility Pack-
age C compiler. It is a script that looks for the link
/usr/ccs/bin/ucbcc to the C compiler. The /usr/ccs/bin/ucbcc
link is available only with the SPROcc package, whose
default location is /opt/SUNWspro. The /usr/ucb/cc interface
is identical to /usr/ccs/bin/ucbcc, except that BSD headers
are used and BSD libraries are linked before base
libraries. The /opt/SUNWspro/man/man1/acc.1 man page is
available only with the SPROcc package.
OPTIONS
The /usr/ucb/cc interface accepts the same options as
/usr/ccs/bin/ucbcc, with the following exceptions:
-Idir Search dir for included files whose names do not begin
with a slash (/) prior to searching the usual direc-
tories. The directories for multiple -I options are
searched in the order specified. The preprocessor
first searches for #include files in the directory
containing sourcefile, and then in directories named
with -I options (if any), then /usr/ucbinclude, and
finally, in /usr/include.
-Ldir Add dir to the list of directories searched for
libraries by /usr/ccs/bin/ucbcc. This option is passed
to /usr/ccs/bin/ld and /usr/lib. Directories specified
with this option are searched before /usr/ucblib and
/usr/lib.
-Y P, dir
Change the default directory used for finding
libraries.
EXIT STATUS
The following exit values are returned:
0 Successful compilation or link edit.
>0 An error occurred.
FILES
/usr/ccs/bin/ld
link editor
/usr/lib/libc
SunOS 5.9 Last change: 24 Feb 1998 1
SunOS/BSD Compatibility Package Commands cc(1B)
C library
/usr/ucbinclude
BSD Compatibility directory for header files
/usr/ucblib
BSD Compatibility directory for libraries
/usr/ucblib/libucb
BSD Compatibility C library
/usr/lib/libsocket
library containing socket routines
/usr/lib/libnsl
library containing network functions
/usr/lib/libelf
library containing routines to process ELF object
files
/usr/lib/libaio
library containing asynchronous I/O routines
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWscpu |
|_____________________________|_____________________________|
SEE ALSO
ld(1), a.out(4), attributes(5)
NOTES
The -Y P, dir option may have unexpected results and should
not be used.
SunOS 5.9 Last change: 24 Feb 1998 2
>
and here's the man page for cc from my linux OS (ubuntu):
(incidentally, cc is linked to gcc)
+ Show Spoiler +
GCC(1) GNU GCC(1)
NAME
gcc - GNU project C and C++ compiler
SYNOPSIS
gcc [-c|-S|-E] [-std=standard]
[-g] [-pg] [-Olevel]
[-Wwarn...] [-pedantic]
[-Idir...] [-Ldir...]
[-Dmacro[=defn]...] [-Umacro]
[-foption...] [-mmachine-option...]
[-o outfile] [@file] infile...
Only the most useful options are listed here; see below for the remain‐
der. g++ accepts mostly the same options as gcc.
DESCRIPTION
When you invoke GCC, it normally does preprocessing, compilation,
assembly and linking. The "overall options" allow you to stop this
process at an intermediate stage. For example, the -c option says not
to run the linker. Then the output consists of object files output by
the assembler.
Other options are passed on to one stage of processing. Some options
control the preprocessor and others the compiler itself. Yet other
options control the assembler and linker; most of these are not docu‐
mented here, since you rarely need to use any of them.
Most of the command line options that you can use with GCC are useful
for C programs; when an option is only useful with another language
(usually C++), the explanation says so explicitly. If the description
for a particular option does not mention a source language, you can use
that option with all supported languages.
The gcc program accepts options and file names as operands. Many
options have multi-letter names; therefore multiple single-letter
options may not be grouped: -dr is very different from -d -r.
You can mix options and other arguments. For the most part, the order
you use doesn’t matter. Order does matter when you use several options
of the same kind; for example, if you specify -L more than once, the
directories are searched in the order specified.
Many options have long names starting with -f or with -W---for example,
-fmove-loop-invariants, -Wformat and so on. Most of these have both
positive and negative forms; the negative form of -ffoo would be
-fno-foo. This manual documents only one of these two forms, whichever
one is not the default.
OPTIONS
Option Summary
Here is a summary of all the options, grouped by type. Explanations
are in the following sections.
Overall Options
-c -S -E -o file -combine -pipe -pass-exit-codes -x language
-v -### --help --target-help --version @file
C Language Options
-ansi -std=standard -fgnu89-inline -aux-info filename -fno-asm
-fno-builtin -fno-builtin-function -fhosted -ffreestanding
-fopenmp -fms-extensions -trigraphs -no-integrated-cpp
-traditional -traditional-cpp -fallow-single-precision
-fcond-mismatch -fsigned-bitfields -fsigned-char -funsigned-bit��‐
fields -funsigned-char
C++ Language Options
-fabi-version=n -fno-access-control -fcheck-new -fconserve-space
-ffriend-injection -fno-elide-constructors -fno-enforce-eh-specs
-ffor-scope -fno-for-scope -fno-gnu-keywords -fno-implicit-tem��‐
plates -fno-implicit-inline-templates -fno-implement-inlines
-fms-extensions -fno-nonansi-builtins -fno-operator-names
-fno-optional-diags -fpermissive -frepo -fno-rtti -fstats
-ftemplate-depth-n -fno-threadsafe-statics -fuse-cxa-atexit
-fno-weak -nostdinc++ -fno-default-inline -fvisibil��‐
ity-inlines-hidden -Wabi -Wctor-dtor-privacy -Wnon-virtual-dtor
-Wreorder -Weffc++ -Wno-deprecated -Wstrict-null-sentinel
-Wno-non-template-friend -Wold-style-cast -Woverloaded-virtual
-Wno-pmf-conversions -Wsign-promo
Objective-C and Objective-C++ Language Options
-fconstant-string-class=class-name -fgnu-runtime -fnext-runtime
-fno-nil-receivers -fobjc-call-cxx-cdtors -fobjc-direct-dispatch
-fobjc-exceptions -fobjc-gc -freplace-objc-classes -fzero-link
-gen-decls -Wassign-intercept -Wno-protocol -Wselector
-Wstrict-selector-match -Wundeclared-selector
Language Independent Options
-fmessage-length=n -fdiagnostics-show-location=[once|every-line]
-fdiagnostics-show-option
Warning Options
-fsyntax-only -pedantic -pedantic-errors -w -Wextra -Wall
-Waddress -Waggregate-return -Wno-attributes -Wc++-compat
-Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconver��‐
sion -Wno-deprecated-declarations -Wdisabled-optimization
-Wno-div-by-zero -Wno-endif-labels -Werror -Werror=* -Wer��‐
ror-implicit-function-declaration -Wfatal-errors -Wfloat-equal
-Wformat -Wformat=2 -Wno-format-extra-args -Wformat-nonliteral
-Wformat-security -Wformat-y2k -Wimplicit -Wimplicit-func��‐
....
there's actually like 20 more pages of detailed info, but you can see that already there are huge differences btwn the two commands.
since all you're doing is just a hello world program to learn the basics, the best way would be to get a different book that is gives you examples specifically for the OS you're using, that way you dont have to tackle these problems and can just get on with learning the programming language.
i'm guessing your book is this:
http://java.sun.com/docs/books/jni/html/start.html
and according to the book,
The -G option instructs the C compiler to generate a shared library instead of a regular Solaris executable file.
when i look for the "shared library" keyword in the manpage for my linux OS, i see that there are some flags that probably do the same thing, look for -shared, -shared-libgcc, -static-libgcc
you can do a man on your own cc, and look for this "shared library" keyword and work out the corresponding flag that you need.
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one other solution that might also help you is that if you're deadset in using solaris, you can run it as a virtual environment under fedora or any other OS.
here's the vmware version of it for solaris 10.
http://www.vmware.com/appliances/directory/420
you should know that this requires installing the vmware (player) software on fedora (shouldnt be that hard) first and then running the vmware image for solaris 10.
vmware and the solaris image are both free.
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