public final class SubcommandLibDemo extends JavaPlugin {
  @Override
  public void onEnable ( ) {
    SubcommandLib. register ( new TestCommand ( ), this ) ;
  }
}

public class TestCommand implements Subcommand {
  @Override
  public @NotNull String getName ( ) {
    return "test" ;
  }
  @Override
  public @NotNull List <Subcommand > getSubcommands ( ) {
    return List. of (
        new ComplexSubcommand ( ), // A more complex subcommand (subcommand1)
        new SimpleSubcommand ( ), // A more simple sumbcommand (subcommand2)
        new TestCommand ( ) // An infinitely recursive subcommand, because why not
    ) ;
  } // This command does not override execute(), so it cannot be executed.
}

public class ComplexSubcommand implements Subcommand {
    @Override
    public @NotNull String getName ( ) {
        return "subcommand1" ;
    }

    @Override
    public @NotNull List <String > getAliases ( ) {
        return List. of ( "alias" ) ;
    }

    @Override
    public boolean execute (@NotNull CommandSender sender, @NotNull List <Either < String, CommandFlag >> arguments ) {
        // Split the arguments into normal arguments in flags, because in this case the order doesn't matter
        List <String > args = SubcommandUtils. getNormalArguments (arguments ) ;
        List <CommandFlag > flags = SubcommandUtils. getFlags (arguments ) ;

        if (args. size ( ) == 1 ) {
            Player player = Bukkit. getPlayerExact (args. getFirst ( ) ) ;
            if (player != null ) {
                sender. sendMessage (ChatColor. GREEN + "Ran subcommand1 on " + args. getFirst ( ) + "!" ) ;
                player. sendMessage (ChatColor. YELLOW + "Someone ran a command on you!" ) ;

                // --optional strikes them with lightning
                if (flags. contains ( new CommandFlag ( "optional" ) { @Override public List <Character > getSuggestedNext (List <CommandFlag > previous ) { return List. of ( ) ; } } ) ) { ;
                    player. getWorld ( ). strikeLightning (player. getLocation ( ) ) ;
                }

                // Check for -f and -r independently, although they can be typed together since they're one character and not CommandOptions
                // CommandFlag.simple() gives you a dummy CommandFlag for comparison purposes
                sender. sendMessage (flags. contains (CommandFlag. simple ( "f" ) ) ? (ChatColor. GOLD + "flag -f specified" ) : (ChatColor. YELLOW + "flag -f not specified" ) ) ;
                sender. sendMessage (flags. contains (CommandFlag. simple ( "r" ) ) ? (ChatColor. GOLD + "flag -r specified" ) : (ChatColor. YELLOW + "flag -r not specified" ) ) ;

                // Check whether --optional-with-option was specified
                // CommandOption.simple() functions the same as CommandFlag.simple()
                if (flags. contains (CommandOption. simple ( "optional-with-option" ) ) ) {
                    // Use the SubcommandUtils.findFromSimple() method to find the full flag
                    CommandOption option = (CommandOption ) SubcommandUtils. findFromSimple (CommandOption. simple ( "optional-with-option" ), flags ) ;
                    if (option. getOption ( ) != null ) {
                        switch (option. getOption ( ) ) {
                            case "option1" -> sender. sendMessage (ChatColor. DARK_PURPLE + "You chose option 1" ) ;
                            case "option2" -> sender. sendMessage (ChatColor. DARK_BLUE + "You chose option 2" ) ;
                            case "pickme!!" -> sender. sendMessage (ChatColor. GREEN + "Your bank account has just been charged $192,331.97." ) ;
                            default -> sender. sendMessage (ChatColor. RED + "That isn't a valid option!" ) ;
                        }
                    } else sender. sendMessage (ChatColor. RED + "You didn't specify an option to --optional-with-option" ) ;
                }
            } else sender. sendMessage (ChatColor. RED + "That player could not be found." ) ;
        } else sender. sendMessage (ChatColor. RED + "You must specify a username!" ) ;

        return true ;
    }

    @Override
    public @NotNull List <String > tabComplete (@NotNull CommandSender sender, @NotNull List <Either < String, CommandFlag >> arguments, String typed ) {
        // Return the names of all online players, or nothing if there's already an argument
        return SubcommandUtils. getNormalArguments (arguments ). isEmpty ( ) ? Bukkit. getOnlinePlayers ( ). stream ( ). map (Player ::getDisplayName ). toList ( ) : List. of ( ) ;
    }

    @Override
    public @NotNull List <CommandFlag > getAllowedFlags (@NotNull CommandSender sender ) {
        return List. of (
                CommandFlag. simple ( "optional" ), // Flag --optional
                new CommandOption ( "optional-with-option" ) { // Flag --optional-with-option
                    @Override
                    public @NotNull List <String > getSuggestedOptions ( ) {
                        return List. of ( "option1", "option2", "pickme!!" ) ; // Suggested parameter choices for tab completion
                    }
                },
                new CommandFlag ( "f" ) { // Flag -f
                    @Override
                    public List <Character > getSuggestedNext (List <CommandFlag > previous ) {
                        // Suggest -r unless it's already been given
                        return previous. contains (CommandFlag. simple ( "r" ) ) ? List. of ( ) : List. of ( 'r' ) ;
                    }
                },
                new CommandFlag ( "r" ) { // Flag -r
                    @Override
                    public List <Character > getSuggestedNext (List <CommandFlag > previous ) {
                        // Suggest -f unless it's already been given
                        return previous. contains (CommandFlag. simple ( "f" ) ) ? List. of ( ) : List. of ( 'f' ) ;
                    }
                }
        ) ;
    }

    // The default behavior for suggestFlags() is to suggest any flags that haven't already been used. In this case, we don't need to override it.
}
 

public class SimpleSubcommand implements Subcommand {
    @Override
    public @NotNull String getName ( ) {
        return "subcommand2" ;
    }

    @Override
    public boolean execute (@NotNull CommandSender sender, @NotNull List <Either < String, CommandFlag >> arguments ) {
        // Send the player nothing but their arguments as a formatted array
        // All the stream stuff does is convert all the arguments into strings
        sender. sendMessage ( Arrays. toString (arguments
                . stream ( )
                . map ( Object ::toString )
                . toArray ( )
        ) ) ;
        return true ;
    }
}

name : SubcommandLibDemo
version : '1.0.0'
main : xyz.dragin.subcommandLibDemo.SubcommandLibDemo
api-version : '1.21'
authors : [ Dragin ]
website : https://dragin.xyz
commands:
  test:
    description : A test command