René Capella - 2021-10-02

Experiencing the same: here is the stack trace:

Exception in thread "main" java.lang.ExceptionInInitializerError
at com.thoughtworks.xstream.XStream.setupConverters(XStream.java:678)
at com.thoughtworks.xstream.XStream.<init>(XStream.java:456)
at com.thoughtworks.xstream.XStream.<init>(XStream.java:381)
at com.thoughtworks.xstream.XStream.<init>(XStream.java:356)
at com.horstmann.violet.framework.file.persistence.XStreamBasedPersistenceService.read(XStreamBasedPersistenceService.java:39)
at com.horstmann.violet.framework.file.persistence.XHTMLPersistenceService.read(XHTMLPersistenceService.java:89)
at com.horstmann.violet.application.menu.FileMenu.getSampleDiagramImage(FileMenu.java:601)
at com.horstmann.violet.application.menu.FileMenu.initFileNewMenu(FileMenu.java:506)
at com.horstmann.violet.application.menu.FileMenu.createMenu(FileMenu.java:121)
at com.horstmann.violet.application.menu.FileMenu.<init>(FileMenu.java:96)
at com.horstmann.violet.application.menu.MenuFactory.getFileMenu(MenuFactory.java:58)
at com.horstmann.violet.application.gui.MainFrame.createMenuBar(MainFrame.java:121)
at com.horstmann.violet.application.gui.MainFrame.<init>(MainFrame.java:88)
at com.horstmann.violet.UMLEditorApplication.createDefaultWorkspace(UMLEditorApplication.java:153)
at com.horstmann.violet.UMLEditorApplication.<init>(UMLEditorApplication.java:108)
at com.horstmann.violet.UMLEditorApplication.main(UMLEditorApplication.java:96)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.util.Comparator java.util.TreeMap.comparator accessible: module java.base does not "opens java.util" to unnamed module @1a27aae3
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:178)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:172)
at com.thoughtworks.xstream.converters.collections.TreeMapConverter.<clinit>(TreeMapConverter.java:59)
... 16 more
</clinit></init></init></init></init></init></init>