Throwing Exception

We have to prepare if user doesn't give a valid coordinate for MapLocation. So, we could throw the exception and asking for another input.

The best place to put our validation is in the constructor in MapLocation class. Because it is called when object is called before created.

class MapLocation : Point
{
    public MapLocation(int x, int y, Map map) : base(x, y)
    {
        if (!map.onMap(this))
        {
            throw new Exception();
        }
    }
}

thisrefers to method that being called. Now, our constructor need Map as an input. If the map is not fulfill the onMap method, it will throw the exception and the object couldn't be created yet.

Meanwhile, In the Game class, we have to catch the exception thrown from MapLocationclass.

class Game
{
    static void Main(string[] args)
    {
        Map map = new Map(8, 5);

        try
        {
            MapLocation mapLoc = new MapLocation(8, 5, map);
        }
        catch (Exception)
        {
            Console.WriteLine("coordinate out of range");
        }

        Console.Read();
    }
}