Is Java installed? To run the Java command, first you must have Java installed. This means either the Java Runtime Environment (JRE) or the full Java Development Kit (JDK).

The Java Runtime Environment (JRE) is what you get when you download Java software. Java technology allows you to work and play in a secure computing environment.

I wrote a Java application that I'd like to run on any machine that has the appropriate Java Runtime Environment installed. I'm used to running apps via the SDK binaries, i.e. "java [application ...