Javalin.start() should throw if startup fails

Actual behavior (the bug) I have another server occupying the port 8080. The Javalin.start() function completes successfully, but Javalin is not running.

Expected behavior Since start() is synchronous, I expect the start() function to throw an exception if Javalin fails to start (e.g. on BindException).

To Reproduce

1. run netcat -l 8080
2. start Javalin on port 8080: Javalin.create().start(8080).

[tipsy]

I’d only suggest to add cause to the second throw - the , e part:

Thanks, missed that one. Fixed in https://github.com/tipsy/javalin/commit/10ebe08b8c10a390baeb0ad2cd607cc285eb1d91.

Wow, you’re really fast! Awesome work.

There’s been a lot of traffic the past few days because of the article in Java Magazine, so I’m trying to respond as quickly as possible 😃

[tipsy]

What about:

} catch (Exception e) {
    log.error("Failed to start Javalin");
    eventManager.fireEvent(JavalinEvent.SERVER_START_FAILED);
    if (e.getMessage() != null && e.getMessage().contains("Failed to bind to")) {
        throw new RuntimeException("Port already in use. Make sure no other process is using port " + port + " and try again.", e);
    } else if (e.getMessage() != null && e.getMessage().contains("Permission denied")) {
        throw new RuntimeException("Port 1-1023 require elevated privileges (process must be started by admin).");
    }
    throw new RuntimeException(e);
}