#3971 Exception trying to set X11 WM_CLASS in JDK9 on Linux

[will69]

JDK9 includes modules since jdk-9-ea+111. There is an exception when trying to set X11 WM_CLASS (aka x11.wmclass) to "jedit" on Linux via reflection. Luckily, jEdit still starts. The culprit is the call to setAccessible. As a consequence, X11 window class names will be different with JDK9, as seen by calling xprop | grep WM_CLASS:

JDK8: WM_CLASS(STRING) = "sun-awt-X11-XFramePeer", "jedit"
JDK9: WM_CLASS(STRING) = "org-gjt-sp-jedit-jEdit", "org-gjt-sp-jedit-jEdit"

Setting that value in the first place was requested here. There does not seem to be any other way to set it. Throwing an exception on startup should be avoided.

[will69]

Since this is an expected behavior on JDK9, the startup exception should be eliminated by inserting

if(!"java.lang.reflect.InaccessibleObjectException".equals(e.getClass().getName()))

before the call to Log.log (sourceforge.net) or at least the log message should be clarified ("Cannot set X11 WM_CLASS to \"jedit\"").

[will69]

The exception can be eliminated by adding the following command line option on JDK9:

-XaddExports:java.desktop/sun.awt.X11=ALL-UNNAMED

This breaks the access-control boundaries defined by the module system. See also JDK-8061972.

xprop | grep WM_CLASS then yields:

WM_CLASS(STRING) = "jedit", "jedit"

Thus, the above command line option should be added when running on JDK9.

[will69]

The syntax has been changed twice. First to

--add-exports=java.desktop/sun.awt.X11=ALL-UNNAMED

and now (around Java 9-ea+149) to

--add-opens=java.desktop/sun.awt.X11=ALL-UNNAMED

[Dale Anson]

Now that Java 9 is out, is your last comment still valid? Has anything else changed?

[Dale Anson]

I've looked into this some more, I get this message when starting jEdit with Java 9 (OpenJDK build 9+181):

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.gjt.sp.jedit.jEdit (file:/home/danson/apps/jedit/current/jedit.jar) to field sun.awt.X11.XToolkit.awtAppClassName
WARNING: Please consider reporting this to the maintainers of org.gjt.sp.jedit.jEdit
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

The OpenJDK mailing list suggests adding

Add-Opens: java.desktop/sun.awt

to the jar manifest. Doing so, and adjusting the jEdit code to not call the illegal access eliminates the message above, but then there is this:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.gjt.sp.jedit.gui.BufferSwitcher (file:/home/danson/apps/jedit/current/jedit.jar) to field javax.swing.plaf.basic.BasicComboBoxUI.listBox
WARNING: Please consider reporting this to the maintainers of org.gjt.sp.jedit.gui.BufferSwitcher
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

I'll continue to look into this.

[Dale Anson]

Fixed in revision 24747. The fix checks the java version and does not execute the code that sets the WM_CLASS if Java 9 and adds the "Add-Opens" line to the manifest file. Tested with both Java 8 and 9. I'll open another ticket for the second warning since it's really a separate issue.