The bug is connected to gcj Java.
However: I lowered gcj-compat priority so that bea/sun/ibm JREs will be the default java (with update-alternative mechanism) when one of those runtimes is installed as well ... right now the gcj-stuff has the same priority. 
With bea & sun Java it works.
... assigning to libgcj maintainer: Michael: It works with the other JREs.

Daniel:  This:

% java -version
java version "1.4.2"
/usr/bin/java: line 17: gcj: command not found

is your problem though.  You call gcj explicitely in the 
/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre/bin/java script.  But the
java-1_4_2-gcj-compat package doesn't depend on gcj (in package gcc-java).

I don't think that it should require gcc-java (because the gcj-compat package
is not for developing but just for running).  So the java script in it
must be fixed to not call gcj, but for instance gij for the -version argument.

Now the other problem with gcj not being able to load the AWT toolkit:
Please someone give me a system where this happens.  apollon seems to have
the bea java installed menawhile.  This _should_ work.

That's true, it works on apollon.

You can play with my testbox odysseus (which is not in yp).
On that machine I installed jdictionary which required and installed java.

Feel free to use it.

Crap.  These gtk classes are implemented in a different shared library,
not in libgcj.so (this is okay).  libgcj, when it tries to load an unknown
class a.b.c tries to find files a-b-c.la and a-b-c.so to load them with
dlopen.  Unfortunately the normal libgcj package only contains the *.so.7*
files, not the .so softlinks or the .la file, because those normally are
only needed for developing.  I'll include them in the libgcj package.

But this doesn't actually make jdictionary work, because when I create the
softlink by hand I now get this:

update UI not overwritten in class: javax.swing.JLayeredPane[0,0,0x27,invalid,translucent,doublebuffered,parent=null,alignmentX=0.5,alignmentY=0.5,border=,maximumSize=java.awt.Dimension[width=32767,height=32767],minimumSize=java.awt.Dimension[width=0,height=27],preferredSize=java.awt.Dimension[width=0,height=27]]
Segmentation fault

This is because not everything is implemented in the AWT toolkit gtk wrapper
in libgcj, so it's something which must be fixed upstream somewhen.

Fixed in Beta9.

@jsmeix: see comment #2 ... don't know if this is a known problem.

Regarding comment #6:
Daniel, see
https://bugzilla.novell.com/show_bug.cgi?id=155288#c2
and bug #155729
and bug #151732 starting there at the 10. comment.

Comment #2 mentioned that the command "java -version", which I think
is a very reasonable command a user might want to enter doesn't work
currently.  Because the wrapper script calls the program "gcj", which
only is available when gcc-java is installed, which isn't the case everywhere.

The solution would be to make the wrapper script actually call "gij", which
also is the more correct executable anyway, as "java" is the runtime
interpreter, corresponding to gij, while gcj is the compiler, i.e.
corresponding to javac.  I'm reopening this one, changing the summary and
assign it to Johannes.

Now it has become exactly bug #155729 ;-)

Thanks for the explanation about "gcj" versus "gij".

I will change
/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre/bin/java
and let it call only "gij".

Fixed and submitted to STABLE.

Let's see what depends on the exact output of "gcj --version"
and fails now because it gets the output of "gij --version"
;-)

Created attachment 73676 [details]
For your information: diff of the changea in the "java" wrapper script.