Learn to Program with Minecraft Plugins, 2nd Edition

Handle Chat Commands

The bit with the @Command at ​①​ tells the system that this function, skyCommand, is responsible for handling the /sky command. That is, when the player types the /sky command, your skyCommand function will be called.

The first thing we need to check is a little awkward; it turns out that the MessageReceiver that gets passed to us here may not be a Player. It could be a Player object, or who knows what else. We want to make sure it’s really a Player, so we’ll check for that explicitly at ​②​, using the Java keyword instanceof. This tests to see if the thing passed in is really a Player. If it is, then we’re going to do the bulk of the command starting at ​③​. (If it’s not a Player, then it’s probably a console command, ...