Guide to solve "Comparison method violates its general contract" issues on windows

[mbien]

update: fix got merged into JDK 23 (and backported to 22.0.2), please use the latest JDK update release: openjdk/jdk#18126 (comment)

Hello there,

as tormented windows user, you might run into a problem where the JFileChooser quits working. This can happen both, during installation (#6339) (since the windows installer uses java too) and also later while using NetBeans (#6295). You should see the following exception in the log and/or error dialogs:

java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.base/java.util.ComparableTimSort.mergeHi(ComparableTimSort.java:870)
	at java.base/java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:487)
	at java.base/java.util.ComparableTimSort.mergeForceCollapse(ComparableTimSort.java:426)
	at java.base/java.util.ComparableTimSort.sort(ComparableTimSort.java:222)
	at java.base/java.util.Arrays.sort(Arrays.java:1041)
	at java.desktop/sun.awt.shell.Win32ShellFolderManager2.get(Win32ShellFolderManager2.java:315)
	at java.desktop/sun.awt.shell.ShellFolder.get(ShellFolder.java:277)
	at java.desktop/javax.swing.plaf.metal.MetalFileChooserUI$DirectoryComboBoxModel.addItem(MetalFileChooserUI.java:1033)
	at java.desktop/javax.swing.plaf.metal.MetalFileChooserUI.doDirectoryChanged(MetalFileChooserUI.java:721)
	at java.desktop/javax.swing.plaf.metal.MetalFileChooserUI$5.propertyChange(MetalFileChooserUI.java:810)
	at java.desktop/java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:343)
	at java.desktop/java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:335)
	at java.desktop/java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:268)
	at java.desktop/java.awt.Component.firePropertyChange(Component.java:8722)
	at java.desktop/javax.swing.JFileChooser.setCurrentDirectory(JFileChooser.java:609)
	at java.desktop/javax.swing.JFileChooser.<init>(JFileChooser.java:363)
	at java.desktop/javax.swing.JFileChooser.<init>(JFileChooser.java:309)
... (more) ...

This is a windows specific JDK bug, which occurs when you have a certain combination of folders/files on your system:
https://bugs.openjdk.org/browse/JDK-8305072

To workaround this issue, you can use a different installer (download page, community installers section) or use the zip distribution.

Once installed (or extracted), you will have to additionally add a flag to your netbeans_default_options property in netbeans.conf:
-J-Djava.util.Arrays.useLegacyMergeSort=true
Alternatively, you can add this flag as argument to your NetBeans windows shortcut (without the -J most likely).

This should workaround the issue until the JDK is fixed. Installing linux would fix it too.

[neilcsmith-net]

Alternatively, you can add this flag as argument to your NetBeans windows shortcut (without the -J most likely).

Thanks @mbien Note that -J is required in the shortcut or on the CLI too to pass Java options. Otherwise you should see Unknown option -Djava.util.Arrays.useLegacyMergeSort=true and the IDE will exit.

[mbien]

Thanks Neil! Updated the text.

[hernandddd]

me sale este error

pueden ayudarem a resolverlo, sale al momento de instalra apache netbeans

[mbien]

fix got merged into JDK 23 -> openjdk/jdk#18126

https://bugs.openjdk.org/browse/JDK-8305072
https://bugs.openjdk.org/browse/JDK-8331058 (backported to JDK 22.0.2)