Java Reference
In-Depth Information
Code 6.3
Source code of the
(badly designed) Room
* Define the exits of this room. Every direction either
* leads to another room or is null (no exit there).
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 (the one that was
* defined in the constructor).
public String getDescription()
return description;
It is a bit more work to find all relevant places in the Game class. The source code is somewhat
longer (it is not fully shown here), and finding all the relevant places takes some patience and care.
Reading the code shown in Code 6.1, we can see that the Game class makes heavy use of the
exit information of a room. The Game object holds a reference to one room in the current-
Room variable and frequently accesses this room's exit information.
In the createRoom method, the exits are defined.
In the printWelcome method, the current room's exits are printed out so that the player
knows where to go when the game starts.
In the goRoom method, the exits are used to find the next room. They are then used again to
print out the exits of the next room we have just entered.
If we now want to add two new exit directions, we will have to add the up and down options in
all these places. However, read the following section before you do this.
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