280940 - link-systems.com NetTutor WWWhiteboard Java error

Status: RESOLVED WORKSFORME

(Core Graveyard :: Java: OJI, defect)

Description

[Frankie]

LinkSystems NetTutor is a graphical chat with math symbols and other teaching
support functions. My organization uses it for several online classes (password
restricted)

The testcase URL is an open demo site. You can also reach it via
http://link-systems.com/ choose the Whiteboard tab, then click "Try It!" on the
right sidebar.

NetTutor works for me in various browsers on Windows 98/2K/XP and Mac 9/X.
However, one of our remote users could not start the whiteboard, with the
following Java Console error in Fedora Core 3 Java 1.4.x Mozilla 1.7.x:

----------------------------------------
java.lang.NullPointerException
        at sun.awt.X11.XMenuPeer.repaintMenuItem(XMenuPeer.java:360)
        at sun.awt.X11.XCheckboxMenuItemPeer.setState(XCheckboxMenuItemPeer.java
:46)
        at java.awt.CheckboxMenuItem.setState(CheckboxMenuItem.java:177)
        at UFgraph.a(UFgraph.java)
        at UFgraph.c(UFgraph.java)
        at UFgraph.c(UFgraph.java)
        at UFgraph.j(UFgraph.java)
        at UFgraph.<init>(UFgraph.java)
        at doodleGraph.a(doodleGraph.java)
        at doodleGraph.<init>(doodleGraph.java)
        at q.a(q.java)
        at q.<init>(q.java)
        at bp.a(bp.java)
        at doodleTool.letsGo(doodleTool.java)
        at doodleTool.start(doodleTool.java)
        at sun.applet.AppletPanel.run(AppletPanel.java:413)
        at java.lang.Thread.run(Thread.java:595)
----------------------------------------

I do not have the resources to determine if this is a Linux/Java bug, a Mozilla
bug, or a syntax error (aka Evangelism).

Comment 1

[Frankie]

Correction: Java 1.5

Comment 2

[doeni]

Tested on Slackware 10.0 with Gnome 2.8 :

1. Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8b2) Gecko/20050323 with JDK
1.4.2_06

 * On the first attempt, I received a NullPointerException but with a different
Java stack
 * The NullPointerException did not reoccur afterwards.

In both tests, the applet seemed to work fine (though each time it crashed
Mozilla when exiting the applet)

2. Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8b2) Gecko/20050323 with JDK
1.5.0_02

 * The exact same Java stack is reported in the Java console
 * And mozilla-bin using all the CPU
 * The applet does not show up.

3. Firefox 1.0 + JDK 1.5.0_02

* Received the same NullPointerException and stack trace as above
* Applet is not showing up either


The issue is very similar and probably the same as reported here :
http://forum.java.sun.com/thread.jspa?threadID=580139&tstart=75 which seems to
be caused by the new XLib implementation on Linux.

One possible workaround could be to pass -Dawt.toolkit=sun.awt.motif.MToolkit to
the Java plugin. Though I don't know how this can be done.

Comment 3

[Pete Zha]

mass reassign to Alfred

Comment 4

[Matthias Versen [:Matti]]

Please report this directly to sund if this still ahppens