Command-line arguments
Parsing and handling arguments passed via the command-line
About
Properly handling command-line arguments passed by the user isn't that straightforward as it looks like. There are a variety of hurdles that can catch you out. The argument handling implementation of kickstartfx it takes care of them automatically.
Parsing arguments
The arguments are passed in the AppArguments class.
KickstartFX will automatically detect and extract any passed arguments that look like properties. This is done because in practice, most users don't understand the difference between a normal argument and an JVM argument. Also, with jpackage, it is not possible to easily pass JVM arguments, e.g. to set a property with -Dkey=value.
After that, the arguments are matched against a picocli command definition. This allows you to use the full feature set of picocli while also keeping control of how to preprocess arguments.
Handling arguments
If your application supports opening generic arguments like file paths or URLs, these have to be handled differently. After all options and parameters are removed from the arguments in the AppArguments class, any leftovers are passed into the AppOpenArguments class. This class will accumulate all generic arguments.
On macOS, applications called via a custom URL scheme require special handling to receive the URL argument. This is implemented in the file AppDesktopIntegration. This is partially why these open arguments have to be buffered like this.
The open arguments are handled when the application is fully started up. How you will handle them is up to you in your application.