System.exit(num) or throw a RuntimeException from main?

Question

I\'ve got a single threaded app that should set the DOS errorlevel to something non-zero if there is a problem. Is it better to throw a RuntimeException, or to use System.ex

Answer 1

It depends how much information you want to report back to the script that starts your program. This can be very important if the script is designed to execute a chain of actions. https://shapeshed.com/unix-exit-codes/

Example: I developed a Java program that calls an external API, downloads the response and saves it to a file. Possible outcomes:

• 0 = OK
• 5 = HTTP Temporarily unavailable
• 6 = Unable to write file to disk

Now my script knows what went wrong, and it could take different actions based on the outcome.

• If response = 0, continue next step in the script
• If response = 5, retry (with a delay)
• If response = 6, stop the script

Bottom line: like any good api, clearly define your input and output parameters and use System.exit.