Re: Java VM version query

FROM : Brent Gulanowski
DATE : Tue Oct 05 20:09:07 2004

Richard,

I wasn't reading sufficiently carefully and missed one point -- you
say that the Java key/dictionary are to be added to the application.
Does this mean that a Foundation tool (which by definition has no
info.plist) cannot access Java classes using this method? Anyway that
is my discovery when I tried to add the key to the info.plist of a
framework since I was testing this using only a tool.

On Sat, 2 Oct 2004 14:41:14 -0400, Richard Van Deren <<email_removed>> wrote:
> Thanks for everybody's help.  This is a report on my problem, several
> solutions along the way.  My goal was to get Apache FOP to work in a
> Cocoa Application, correctly.
>        BTW, I am still looking for a query in Objective-C Cocoa to query the
> JVM Version.  Thanks for the Java examples.
>
> I was feeling so alone just talking to Sun Java error messages and
> reading Apple Java error messages and documentation.
>
> Here is my problem restated, before I give you the solution.
>
> I was first hit by Apple's, Java 1.4.2 Update 1.  This created an
> error where Java AWT could not be started on the main thread.  That is
> the Objective-C Cocoa NSThread, not a Java Thread.
>        I am happy now that I know enough of about Objective-C threads to get
> me in trouble.  Using a detached worker thread I was then able to FOP
> again.
>                You can reproduce this problem with: TestXSLT, download URL below.
>                        2004-10-02 13:49:08.736 TestXSLT[10860] Apple AWT Java VM was loaded
> on first thread -- can't start AWT.
>                        2004-10-02 13:49:08.790 TestXSLT[10860] java/lang/InternalError:
> Can't start the AWT because Java was started on the first thread.
>
> I then rewrote my working Apache FOP Cocoa system service as a
> Framework.    I embedded my framework and the NSClassFromString
> function returned nil.    I then learned about the obj-c foundation
> NSJava ... functions.  They lead me to the now famous "Unsupported
> major minor version 48" message.  It was fun learning about Java byte
> codes and remembering basic programming rules about writing clear
> messages.  It took me a couple of days to translate this message to
> "The Java VM that you are running on is not in the range that this
> class was compiled. Please check your VM version or recompile this
> class."
>
> Now that I had a problem, with your help and a little googling, I was
> able to edit my info.plist and I added the following key with a
> dictionary:
>        <key>Java</key>
>        <dict>
>                <key>JVMVersion</key>
>                <string>1.4+</string>
>        </dict>
> This was needed because I was using Xcode 1.5 native target and Java is
> not supported in the inspector, however the target inspector allows for
> editing the info.plist as a file in the Properties tab.  The
> application is edited not the framework where the java is located.
> This confused be for a while.  Note this was a legacy cocoa framework.
> I used this form because Java is not supported yet as a native target.
> The framework is also used because Apache FOP needs to be a plug-in of
> some sort.
>
> I will post my framework to the Apache FOP group and/or put it on my
> web site when it matures a little.
>
> I am a fan of Formatting Objects.  I hope Apple will be someday.
>
> sites I used to solve this problem.
> Formatting Objects:                                      http://xml.apache.org/fop/
> TestXSLT Cocoa example error:
> http://www.entropy.ch/phpbb2/viewtopic.php?t=1450
> TestXSLT download:                              http://www.entropy.ch/software/macosx/#testxslt
> Framework Tutorial Movie:
> http://rentzsch.com/cocoa/embeddedFrameworks
> Reported as apple bug:
> https://bugreport.apple.com/cgi-bin/WebObjects/RadarWeb.woa
> http://bugreport.apple.com
> Problem ID:  3776689 Title: Update 1: Apache FOP, Formatting Objects
> fails when starting AWT
> Originator: Richard Van Deren  Closed Created Date: 26-Aug-2004 04:22 AM
> ________________________________________________________
> Rich Van Deren
>
> http://homepage.mac.com/rvanderen/WhereIsRich.html
> On Oct 2, 2004, at 1:06 AM, Mike Hall wrote:
>
> >> Richard Van Deren wrote:
> >
> >> How do you know which version of the Java VM an Cocoa application is
> >> using?
> >>
> >> My application seems to be using Java VM 1.3 when it should be using
> >> Java
> >> VM 1.4
> >
> >> Cocoa-Java programs use a different mechanism than "pure Java"
> >> programs do.
> >
> >> The "pure Java" mechanism is a "Java" dictionary in Info.plist:
> >
> > Ah, I was forgetting Cocoa-java was different here.
> >
> > I did come across this fairly new documentation, not Cocoa specific
> > but if of interest.
> >
> > http://developer.apple.com/technotes/tn2002/tn2110.html
> >
> > The semi-serious caveat I mentioned in passing.
> >
> > http://developer.apple.com/qa/qa2001/qa1342.html
> >
> > Pretty brief and not real encouraging to Cocoa-Java development. List
> > clarifications were actually more detailed but not much better as far
> > as your coding prospects as I remember and you can find those on the
> > archives.
> >
> > Since again I use my own Cocoa interface and that is JNI based I guess
> > I'm safe here.
> > Hard to say. With either normal, somewhat supported Cocoa-Java or my
> > own I figure it's like anything else, you try it and what works is ok
> > and what doesn't isn't.
> >
> > Well, I didn't want to leave this with some mysterious and vague and
> > unsubstantited accusation. I can go back to bed now feeling better.
> >
> > Mike Hall    mikehall at spacestar dot net
> > http://www.spacestar.net/users/mikehall
> >
> >
> >
> >
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>



--

Brent Gulanowski
http://www.boredastronaut.com