import java.util.Set;import java.util.HashMap;import java.util.Iterator;/** * 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.  For each existing exit, the room  * stores a reference to the neighboring room. *  * @author  Michael Kolling and David J. Barnes * @version 2006.03.30 */public class Room {    private String description;    private HashMap<String, Room> exits;        // stores exits of this room.    /**     * 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;        exits = new HashMap<String, Room>();    }    /**     * Define an exit from this room.     * @param direction The direction of the exit.     * @param neighbor  The room to which the exit leads.     */    public void setExit(String direction, Room neighbor)     {        exits.put(direction, neighbor);    }    /**     * @return The short description of the room     * (the one that was defined in the constructor).     */    public String getShortDescription()    {        return description;    }    /**     * Return a description of the room in the form:     *     You are in the kitchen.     *     Exits: north west     * @return A long description of this room     */    public String getLongDescription()    {        return "You are " + description + ".\n" + getExitString();    }    /**     * Return a string describing the room's exits, for example     * "Exits: north west".     * @return Details of the room's exits.     */    private String getExitString()    {        String returnString = "Exits:";        Set<String> keys = exits.keySet();        for(String exit : keys) {            returnString += " " + exit;        }        return returnString;    }    /**     * Return the room that is reached if we go from this room in direction     * "direction". If there is no room in that direction, return null.     * @param direction The exit's direction.     * @return The room in the given direction.     */    public Room getExit(String direction)     {        return exits.get(direction);    }}