Kotlin Programming: The Big Nerd Ranch Guide, 2nd Edition

Combat in NyetHack

Adding combat to NyetHack will put to use all that you have learned about object-oriented programming.

Some rooms in NyetHack – the long corridor and dungeon – will contain a monster for your hero to vanquish in the most graphic way that you know how: by nullifying it.

Create a new kind of room called a MonsterRoom to define a room capable of holding a monster. Add a monster property of nullable type Monster? to the new MonsterRoom class and initialize it by assigning it a Goblin. Also, override Room’s description to let the player know whether the room has a monster to fight.

Listing 17.9  Defining rooms with monsters (Room.kt)

open class Room(val name: String) {

    protected open val status = "Calm"

    open