Build A Clash Of Clans Troop Calculator

For my first attempt at writing a program that consists of more than one class, I am trying to build a Clash of Clans troop calculator. It will allow the user to configure an army composition and return the cost to train, the total damage per second, and the total training time. Cost and damage will vary based on the levels of each type of troop. Total troop capacity will depend on the number and level of the available army camps. URL...

Eventually it will need a GUI, but I'm just trying to plan out the components right now. I started by writing a masterclass called Troop, and subclasses for each type of troop.Troop class:

public class Troop {
private int qty;
private int level;
private static int HOUSING_SPACE;
private static int TRAINING_TIME;
private int elixirCost = 0;
private int darkElixirCost = 0;
private int damagePerSecond = 0;
private int hitPoints = 0;

[code]....

I made each type of troop its own class because 1) the setElixirCost(), setDamagePerSecond(), and setHitPoints() methods will all use different values for each different troop type and 2) I thought building an Army of one of each object would be the easiest way.

Now I'm trying to figure out the best way to build the Army class. It will basically just be a collection of Troop objects, with a few methods to return the total training time, total elixir cost, total hitpoints, and total damage per second. Should it be its own class? I thought about making it just an array of Troops, but it needs to have its own field for max housing space so the client can warn the user to stop adding troops when all army camps are full.