It was written as an applet (more than 10 years ago) instead of an application (so there is no main in the code).
You can use appletviewer to view it. (need an html page with applet tag)
Please check out sun's web site and find out more information.
You can check out [url=http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?p=1614]traffic light control applet with EJS[/url]. You can download jar file version which can be run as an application. (just double click the downloaded ajr file).
And you can modify it with EJS and create new version,too!