Practical Java: The Java Shell (jshell) on macOS.
The Java Shell (jshell) is a handy tool for trying out concepts or ideas without the need for creating whole projects in Java. It's a bit like the REPL environment for Python or the Command Window for Matlab.
While this demo is on the macOS terminal, it also works in the Windows Command Prompt or PowerShell applications, as well as standard Linux terminals.
The jshell utility is available on Java 9 or greater. In this case, I am using Java 14.