I need to run the following command to run a program in Ubuntu.
Java -Dprism.forceGPU=true -jar quantumVITAS-0.1.0.jar
I got an error "Java not found"
I have downloaded the last version of JRE.
Ubuntu, and Linux in general, is case sensitive. So
Java are two different commands. If you installed the latest version of the JRE (and not just downloaded it ;) ), you should have the command
java available. But it seems you're trying to use the command
Java, which your system doesn't know about.