public void run() {
		Command command;
		while (true) {
			command = ConsoleIO.getUserInput();
			// Command not found
			if (command == null) {
				System.out.println(UNKNOWN_COMMAND);
			} else {
				System.out.println(command.execute(this));
				// Special case
				if (command instanceof Exit) {
					break;
				}
			}
		}
	}