Re: NPE in parser->getDOMImplementation() with CNI

[Sam Ruby <rubys at intertwingly dot net>]

Andrew Haley wrote:
> Mark Wielaard wrote:
> > On Sun, 2009-06-21 at 16:46 +0100, Andrew Haley wrote:
> > > Sam Ruby wrote:
> > > > I'm trying to develop a JAXP implementation using CNI, but I get a
> > > > NullPointerException when I try to get a DOMImplementation.  I've
> > > > attached a small script (tested on Ubuntu 9.04) which demonstrates the
> > > > problem.
> > > >
> > > > Any help would be appreciated.
> > > Congratulations on this excellent test case.  Next time I want to tell
> > > people how to do it right, I'll point them at your posting.
> > >
> > > However, I get
> > >
> > >  $ sh ~/testdomimpl.sh
> > > gnu.xml.dom.DomDocumentBuilderFactory@160ecdad
> > > gnu.xml.dom.DomDocumentBuilder@15ffbc45
> > > gnu.xml.dom.DomImpl@15ef0ee5
> > >
> > > gnu.xml.dom.DomDocumentBuilderFactory@2df0bea7
> > > gnu.xml.dom.DomDocumentBuilder@2de03d5f
> > > gnu.xml.dom.DomImpl@2dd0bfdf
> > >  $ gcj --version
> > > gcj (GCC) 4.4.0 20090307 (Red Hat 4.4.0-0.23)
> > I get the same with that version of gcj.
> > But on an older gcj installation:
> > gcj (Debian 4.3.2-2) 4.3.2
> >
> > gnu.xml.dom.DomDocumentBuilderFactory@6992f029
> > gnu.xml.dom.DomDocumentBuilder@647a3539
> > gnu.xml.dom.DomImpl@64826fa9
> >
> > gnu.xml.dom.DomDocumentBuilderFactory@17d5dffb
> > gnu.xml.dom.DomDocumentBuilder@12bcf52b
> > java.lang.NullPointerException
> >    at java.io.PrintStream.println(PrintStream.java:473)
> >
> > That is somewhat strange since that method seems fine:
> >   public void println (Object obj)
> >   {
> >     print(obj == null ? "null" : obj.toString(), true);
> >   }
> >
> > So maybe just upgrading to a newer Fedora and gcc 4.4 will be the
> > solution, although I don't completely get what goes wrong on the old
> > install.
>
> I have no problem with 4.3 either.  I think this may be an install
> problem or some sort of library path problem.
>
> If you can point me to a failure I can debug I'll have a look.

The script I provided fails with Ubuntu 9.04.  The only things one needs 
to add to a fresh install get to the failure is:

  apt-get install gcj libjaxp1.3-java-gcj

gcj -v reports "gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)"

Downloading the latest Fedora-11-i686-Live.iso, the script passes after 
I change the gcjh line to point to /usr/share/java/jaxp_parser_impl.jar.

gcj -v there reports "gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC)".

Testing on an older version of Ubuntu (Hardy/8.04.2) also works.  Gcj -v 
there reports "gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu3)".

> Andrew.

- Sam Ruby