Cannot run executable- .deb or .jar

[ghost]

I get the same error with either the .zip'd .jar or if the .deb's installed w/ dpkg:

Exception in thread "main" java.lang.ExceptionInInitializerError                                                                                      
        at com.thoughtworks.xstream.XStream.setupConverters(XStream.java:807)                                                                         
        at com.thoughtworks.xstream.XStream.<init>(XStream.java:574)                                                                                  
        at com.thoughtworks.xstream.XStream.<init>(XStream.java:496)
        at com.thoughtworks.xstream.XStream.<init>(XStream.java:465)
        at com.thoughtworks.xstream.XStream.<init>(XStream.java:411)
        at com.thoughtworks.xstream.XStream.<init>(XStream.java:378)
        at com.swingsane.preferences.XStreamUtility$1.<init>(XStreamUtility.java:26)
        at com.swingsane.preferences.XStreamUtility.loadXStream(XStreamUtility.java:26)
        at com.swingsane.preferences.XStreamUtility.getXStream(XStreamUtility.java:20)
        at com.swingsane.preferences.SwingSanePreferencesImpl.load(SwingSanePreferencesImpl.java:61)
        at com.swingsane.gui.Main.loadPreferences(Main.java:193)
        at com.swingsane.gui.Main.main(Main.java:221)
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 @6a6cb05c
        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:337)
        at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:281)
        at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:176)
        at java.base/java.lang.reflect.Field.setAccessible(Field.java:170)
        at com.thoughtworks.xstream.core.util.Fields.locate(Fields.java:39)
        at com.thoughtworks.xstream.converters.collections.TreeMapConverter.<clinit>(TreeMapConverter.java:50)
        ... 12 more

I have both 'oracle-java9-installer' & 'oracle-java9-set-default' installed. Running KDE Neon dev-stable (Ubuntu 16.04).