Having EPEL respository active, using software gui I removed all the OpenJava or OpenJDK stuff; did a search on java and unchecked using good judgement. Some things like json-glib or python-javapackages or tzdata-java I left alone.
then i did a
yum install jdk-8u191-linux-x64.rpm which is from oracle.
That shows up in software gui as
jdk1.8-2000:18.104.22.168-fcs with no Open wording, and all the OpenJava or OpenJDK stuff is not installed.
After that it works only using java -jar StigViewer.jar
If I do just java StigViewer.jar I still get the error, and if I double click on the .jar file from the windows explorer it opens the file like it was a container.
When installing centos 7.6; I chose Server with GUI and I think there was a choice for java stuff but if there was I know I didn't choose, so it seems centos installs openjava automatically to some extent.
oracle jdk-8u201-linux-x64.rpm results in
/usr/bin/java link to
/etc/alternatives/java which then points to
it is THIS oracle java that works with this stigviewer.jar file only by
java -jar stigviewer.jar
Other software like Octave and plplot rely on OpenJDK Headless Runtime Environment 8 which is
java-1.8.0-openjdk-headless-1:22.214.171.124 and that results in the
/usr/bin/java still linking to
/etc/alternatives/java and that links to
/usr/lib/jvm/java-1.8.0-openjdk-126.96.36.199.b09-2.el7_6.x86_64/jre/bin/java which is no workie for this stigviewer.jar file.
So I can remember to manually run Oracle's
/usr/java/jdk1.8.0_201-amd64/jre/bin/java when I need to. It seems once OpenJDK is at all installed, the oracle rpm will not overwrite the links.