Question

I’m working on a text-based adventure game and I’m trying to externalise as much of the setup as possible so that I can work with a friend who wants to write the storyline. I have three classes so far. A room class with a title, description, and an array of Exits. Also an Exit class with the following constructor.

public Exit(int direction, Room connection);

Exits also have public int variables referring to the different directions:

public static final int NORTH = 0;

This is all so I can set up an exit on a room by saying:

Room r = new Room("Title","Description");
Room r2 = new Room("Title", "Description");

r.addExit(new Exit(Exit.NORTH, r2);

This would make an exit on the room r that is on the north side and leads to the room r2. Now for the externalisation I’m trying to make a .txt file where I can simply put the current room number, the exit direction (string), and the room number it leads to.

I can do this just fine as far as reading the file goes but where I’m struggling is when I’m setting up the direction, I can’t say

Exit. /*String read from file*/

So how can I access those public integers from the Exit class using a string from the txt file?

Answer 1

The quick and dirty fix is to implement a method to do string comparison and return the appropriate constant. But you should also consider using an enum as suggested by BRPocock, it’s a much cleaner way to do it.

int directionFromStr(String str) {
    // Putting the string constant on the left side of the expression guards against null input
    if ("NORTH".equalsIgnoreCase(str)) return Exit.NORTH;
    if ("SOUTH".equalsIgnoreCase(str)) return Exit.SOUTH;
    if ("EAST".equalsIgnoreCase(str)) return Exit.EAST;
    if ("WEST".equalsIgnoreCase(str)) return Exit.WEST;

    // You could also return -1 or something like that
    throw new IllegalArgumentException("bad direction");
}