Need Code in Java

Part I:

Imagine you would like to allow rooms to have a new type of exit (e.g. "up"). Identify each class and method that you would have to change in order to allow for this type of exit. Briefly describe the changes you would make in each class and method that you identified.

Several methods in the Game class contain repeated functionality. Specifically, the printWelcome method and the goRoom methods both print a description of the current room and a list of the exits. As we have learned, having the same functionality implemented in multiple locations can lead to the introduction of errors when software is modified. Correct this problem by factoring the common functionality out of these methods into a method of its own. Then call this new method each place the description and exits are to be displayed.

/** * Class Room - a room in an adventure game. * * This class is part of the "World of Zuul" application. * "World of Zuul" is a very simple, text based adventure game. * * A "Room" represents one location in the scenery of the game. It is * connected to other rooms via exits. The exits are labelled north, * east, south, west. For each direction, the room stores a reference * to the neighboring room, or null if there is no exit in that direction. * * @author Michael Klling and David J. Barnes * @version 2016.02.29 */ public class Room { public String description; public Room northExit; public Room southExit; public Room eastExit; public Room westExit;

/** * Create a room described "description". Initially, it has * no exits. "description" is something like "a kitchen" or * "an open court yard". * @param description The room's description. */ public Room(String description) { this.description = description; }

/** * Define the exits of this room. Every direction either leads * to another room or is null (no exit there). * @param north The north exit. * @param east The east east. * @param south The south exit. * @param west The west exit. */ public void setExits(Room north, Room east, Room south, Room west) { if(north != null) { northExit = north; } if(east != null) { eastExit = east; } if(south != null) { southExit = south; } if(west != null) { westExit = west; } }

/** * @return The description of the room. */ public String getDescription() { return description; }

}

/** * This class is the main class of the "World of Zuul" application. * "World of Zuul" is a very simple, text based adventure game. Users * can walk around some scenery. That's all. It should really be extended * to make it more interesting! * * To play this game, create an instance of this class and call the "play" * method. * * This main class creates and initialises all the others: it creates all * rooms, creates the parser and starts the game. It also evaluates and * executes the commands that the parser returns. * * @author Michael Klling and David J. Barnes * @version 2016.02.29 */

public class Game { private Parser parser; private Room currentRoom; /** * Create the game and initialise its internal map. */ public Game() { createRooms(); parser = new Parser(); }

/** * Create all the rooms and link their exits together. */ private void createRooms() { Room outside, theater, pub, lab, office; // create the rooms outside = new Room("outside the main entrance of the university"); theater = new Room("in a lecture theater"); pub = new Room("in the campus pub"); lab = new Room("in a computing lab"); office = new Room("in the computing admin office"); // initialise room exits outside.setExits(null, theater, lab, pub); theater.setExits(null, null, null, outside); pub.setExits(null, outside, null, null); lab.setExits(outside, office, null, null); office.setExits(null, null, null, lab);

currentRoom = outside; // start game outside }

/** * Main play routine. Loops until end of play. */ public void play() { printWelcome();

// Enter the main command loop. Here we repeatedly read commands and // execute them until the game is over. boolean finished = false; while (! finished) { Command command = parser.getCommand(); finished = processCommand(command); } System.out.println("Thank you for playing. Good bye."); }

/** * Print out the opening message for the player. */ private void printWelcome() { System.out.println(); System.out.println("Welcome to the World of Zuul!"); System.out.println("World of Zuul is a new, incredibly boring adventure game."); System.out.println("Type 'help' if you need help."); System.out.println(); System.out.println("You are " + currentRoom.getDescription()); System.out.print("Exits: "); if(currentRoom.northExit != null) { System.out.print("north "); } if(currentRoom.eastExit != null) { System.out.print("east "); } if(currentRoom.southExit != null) { System.out.print("south "); } if(currentRoom.westExit != null) { System.out.print("west "); } System.out.println(); }

/** * Given a command, process (that is: execute) the command. * @param command The command to be processed. * @return true If the command ends the game, false otherwise. */ private boolean processCommand(Command command) { boolean wantToQuit = false;

if(command.isUnknown()) { System.out.println("I don't know what you mean..."); return false; }

String commandWord = command.getCommandWord(); if (commandWord.equals("help")) { printHelp(); } else if (commandWord.equals("go")) { goRoom(command); } else if (commandWord.equals("quit")) { wantToQuit = quit(command); }

return wantToQuit; }

// implementations of user commands:

/** * Print out some help information. * Here we print some stupid, cryptic message and a list of the * command words. */ private void printHelp() { System.out.println("You are lost. You are alone. You wander"); System.out.println("around at the university."); System.out.println(); System.out.println("Your command words are:"); System.out.println(" go quit help"); }

/** * Try to go in one direction. If there is an exit, enter * the new room, otherwise print an error message. */ private void goRoom(Command command) { if(!command.hasSecondWord()) { // if there is no second word, we don't know where to go... System.out.println("Go where?"); return; }

String direction = command.getSecondWord();

// Try to leave current room. Room nextRoom = null; if(direction.equals("north")) { nextRoom = currentRoom.northExit; } if(direction.equals("east")) { nextRoom = currentRoom.eastExit; } if(direction.equals("south")) { nextRoom = currentRoom.southExit; } if(direction.equals("west")) { nextRoom = currentRoom.westExit; }

if (nextRoom == null) { System.out.println("There is no door!"); } else { currentRoom = nextRoom; System.out.println("You are " + currentRoom.getDescription()); System.out.print("Exits: "); if(currentRoom.northExit != null) { System.out.print("north "); } if(currentRoom.eastExit != null) { System.out.print("east "); } if(currentRoom.southExit != null) { System.out.print("south "); } if(currentRoom.westExit != null) { System.out.print("west "); } System.out.println(); } }

/** * "Quit" was entered. Check the rest of the command to see * whether we really quit the game. * @return true, if this command quits the game, false otherwise. */ private boolean quit(Command command) { if(command.hasSecondWord()) { System.out.println("Quit what?"); return false; } else { return true; // signal that we want to quit } } }

The room class and the game class are shared.