@ed-nielsen
Your are using a way outdated TripleA version (1.9).
TripleA 1.9 ran with Java 6.
Please try again using either the current stable version
https://github.com/triplea-game/triplea/releases/tag/2.5.22294
or maybe the current prerelease (in case you want to try it out)
https://github.com/triplea-game/triplea/releases
Please note that between 1.9 and the current version(s) a lot has changed. So after installing a newer version you should redownload the maps.
While you can install and run different TripleA versions side by side the map-files have been changed and you might experience compatibility issues. So I recommend to perform either a clean install or to be absolutely sure to point to different map-directories in case you want to keep 1.9 and its map files for any reason.
Also please note that with the newer versions of TripleA you are no longer dependent on a systemwide installed TripleA. The newer versions come bundled with the (at that time current) Java version that is installed inside the TripleA installation and used exclusively by TripleA.
For example the current stable (2.5.22294) runs with bundled Java 11.0.6.