You might have noticed that U.S. government advises to disable Java due to serious security risks in Java version 1.7
However please note that the possible exploits affect only Java applets. That means Java applications running in internet browser. Expert Lotto is a desktop application and it doesn't open or download any HTML pages from the web.
So it is safe to keep Java 1.7 installed on your computer to run Expert Lotto as long as you disable or remove Java plugin from your internet browser.
(Alternatively you can wait till a new version of Java is released with the security holes patched. But it might take a few weeks.)