serial comm. with rxtx, GPSExplorer, and GCJ -- runtime exception

[David Daney]

Michael Mohr wrote:
> Hello,
> 
> I'm currently attempting to use GCC 4.1's gcj to compile a medium-sized (6000-line) java application.  Unfortunately, it requires raw access to serial ports, as implemented by RXTX.  It appears that RXTX has already been modified to compile using CNI; however, the port appears to be in early alpha stage.
> 
> I am able to compile RXTX (mostly) without complaint.  I am also able to compile my application -- GPSExplorer -- with no warnings or errors using GCC 4.1.  However, it exits when run with the following exception:
> 
> Exception in thread "main" java.lang.UnsupportedOperationException
>    at gnu.java.awt.peer.gtk.GdkGraphicsEnvironment.getAllFonts (lib-gnu-java-awt-peer-gtk.so)
>    at GPSExplorer.<init> (GPSExplorer)
>    at GPSExplorer.main (GPSExplorer)
> 

Looks like GraphicsEnvironment.getAllFonts() is not supported by your 
libgcj.

> The program makes use of the AWT and Swing classes.  It runs perfectly under any JVM after 1.2 (and probably before, but I haven't tested that far back).  I compile and link GPSExplorer as follows:
> 
> rm -f *.o *.s GPSExplorer
> 
> for x in *.java
> do
>   gcj -classpath .:$PWD/RXTX/RXTX.jar -c $x
> done
> 
> gcj *.o -L$PWD/RXTX -lrxtx -o GPSExplorer --main=GPSExplorer
> 
> As I see it, there are 3 possibilities:
>   o Something is wrong with the app in question, GPSExplorer

Perhaps.

>   o Something went wrong with the CNI RXTX port

Again, perhaps, but that is not the problem you are seeing.

>   o Something isn't right with GCJ
> 

Yeah.  The AWT support is not complete yet.


> The text of the error leads me to Door #3, but I could be very wrong.  This is my first attempt to compile a large Java application using GCJ.
> 
> Here's the output of gcc -v:
> Using built-in specs.
> Target: i686-pc-linux-gnu
> Configured with: /var/tmp/portage/gcc-4.1.0-r1/work/gcc-4.1.0/configure --prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.1.0 --includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include --datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0 --mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/man --infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/info --with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include/g++-v4 --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --disable-libunwind-exceptions --disable-multilib --disable-libmudflap --disable-libssp --enable-java-awt=gtk --enable-languages=c,c++,java,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
> Thread model: posix
> gcc version 4.1.0 (Gentoo 4.1.0-r1)
> 
> When I enable -Wall, I get hundreds of warnings, all of which are either:
>    o warning: Discouraged redundant use of 'public' modifier in declaration of abstract method 
>    o warning: An empty declaration is a deprecated feature that should not be used.
> 
> Other than those two errors, nothing is reported.  This is the contents of GPSExplorermain.i after the final link with -save-temps:
> 

Then don't enable -Wall.


David Daney