Java error when opening the editor

Hello,

I'm having the following error when trying to open any of the .m files with the Matlab editor:

Exception in thread "AWT-EventQueue-0": java.lang.NoClassDefFoundError: Could not initialize class com.mathworks.widgets.text.mcode.MSettingsInitializer
	at com.mathworks.widgets.text.mcode.analyzer.CodeAnalyzerLayer.isMLintEnabledInPreferences(CodeAnalyzerLayer.java:411)
	at com.mathworks.widgets.text.mcode.analyzer.CodeAnalyzerLayer.shouldShow(CodeAnalyzerLayer.java:404)
	at com.mathworks.widgets.text.mcode.analyzer.CodeAnalyzerLayer.possiblyEnableOrDisableLayer(CodeAnalyzerLayer.java:166)
	at com.mathworks.widgets.text.mcode.analyzer.CodeAnalyzerLayer.settingsChanged(CodeAnalyzerLayer.java:444)
	at com.mathworks.widgets.text.MWEditorUI.settingsChange(MWEditorUI.java:479)
	at org.netbeans.editor.EditorUI.modelChanged(EditorUI.java:655)
	at org.netbeans.editor.EditorUI.installUI(EditorUI.java:357)
	at com.mathworks.widgets.text.MWEditorUI.installUI(MWEditorUI.java:600)
	at org.netbeans.editor.BaseTextUI.installUI(BaseTextUI.java:197)
	at javax.swing.JComponent.setUI(JComponent.java:666)
	at javax.swing.text.JTextComponent.setUI(JTextComponent.java:328)
	at org.netbeans.editor.BaseKit.install(BaseKit.java:514)
	at javax.swing.JEditorPane.setEditorKit(JEditorPane.java:1054)
	at javax.swing.JEditorPane.setContentType(JEditorPane.java:978)
	at com.mathworks.widgets.SyntaxTextPaneMultiView.setContentType(SyntaxTextPaneMultiView.java:519)
	at com.mathworks.mde.editor.EditorView.initSyntaxTextPane(EditorView.java:820)
	at com.mathworks.mde.editor.EditorView.<init>(EditorView.java:222)
	at com.mathworks.mde.editor.EditorView.<init>(EditorView.java:153)
	at com.mathworks.mde.editor.EditorViewClient.init(EditorViewClient.java:232)
	at com.mathworks.mde.editor.EditorViewClient.<init>(EditorViewClient.java:181)
	at com.mathworks.mde.editor.MatlabEditorApplication.createEditorViewClient(MatlabEditorApplication.java:693)
	at com.mathworks.mde.editor.MatlabEditorApplication.createEditorViewClient(MatlabEditorApplication.java:678)
	at com.mathworks.mde.editor.MatlabEditorApplication.createEditorViewClientFromExistingFile(MatlabEditorApplication.java:670)
	at com.mathworks.mde.editor.MatlabEditorApplication.access$300(MatlabEditorApplication.java:73)
	at com.mathworks.mde.editor.MatlabEditorApplication$4.runWithOutput(MatlabEditorApplication.java:395)
	at com.mathworks.jmi.AWTUtilities$Invoker$2.watchedRun(AWTUtilities.java:475)
	at com.mathworks.jmi.AWTUtilities$WatchedRunnable.run(AWTUtilities.java:436)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
	at java.awt.EventQueue.access$500(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.awt.EventQueue$3.run(EventQueue.java:703)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

I'm on Ubuntu 16.04 and my java version is the following:

openjdk version "1.8.0_222"
OpenJDK Runtime Environment (build 1.8.0_222-8u222-b10-1ubuntu1~16.04.1-b10)
OpenJDK 64-Bit Server VM (build 25.222-b10, mixed mode)

Does anybody have a clue of what it is happening? I didn't upgrade java nor matlab before having this problem.

I'm using matlabM2019a, but even after installing matlabR2019b I get the same error.

Answer 1

[Enrica Soria]

For me, removing the preference folder was the solution. To do so, type the following in your terminal:

cd ~/.matlab 
mv R2019a R2019a_removed

[Kepeng Qiu]

That's great!!!

I have used your idea to solve the same problem.

'''

Operating system: windows 10

MATLAB version: R2019b

java version: Java 1.8.0_202-b08

'''

I just deleted this folder 'R2019b' at the path

'C:\Users\yourname\AppData\Roaming\MathWorks\MATLAB\R2019b' and restarted MATLAB.