public override void Happen(Field field)
{
ConstructorInfo constructor = fieldObjectType.GetConstructor(
new Type[] { typeof(Field), typeof(int), typeof(int) } );
FieldObject newObject =
(FieldObject)constructor.Invoke (new object [] { field, field.randomX (), field.randomY () } );
// newObject.x = field.randomX ();
// newObject.y = field.randomY ();
// newObject.field = field;
field.AddFieldObject (newObject);
}
