class FirstLogin extends JavaPlugin {
    private Map<String, CommandHandler> handlers = new HashMap<>();

        //register command handlers at start
    public void onEnable() {
        FirstHelpCommandHandler firstHelp = new FirstHelpCommandHandler();
        handlers.put(firstHelp.getName(), firstHelp);
    }

    public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args) {
        boolean isCommand = false; //to avoid tons of return statements

        if (sender instanceof Player) {
            if(handlers.containsKey(cmd.getName())) {
                isCommand = true;
                handlers.get(cmd.getName()).process((Player) sender, cmd, commandLabel, args);
            }
        }

        return isCommand;
    }
}

//the "contract" for each command
interface CommandHandler {
    void process(Player player, Command cmd, String cmdLabel, String[] args);
    String getName();
}

//handle specific command
class FirstHelpCommandHandler implements CommandHandler {
    public void process(Player player, Command cmd, String cmdLabel, String[] args) {
        player.sendMessage("/listp: Lists the number of players joined to date.");
        player.sendMessage("/pnames: Lists all the names off players that joined the server.");
        player.sendMessage("/owner: Shows the owner of the servers name.");
        player.sendMessage("/onlinep: Shows how many players are currently online.");
        player.sendMessage("/firsthelp: Shows this to the player.");
    }

    public String getName() {
        return "firsthelp";
    }
}