static void Main(string[] args)
{
CoffeeMaker misterCoffee = new CoffeeMaker();
Oven oldToasty = new Oven();
// Method can take any class that inherits from appliance
MonitorPower(misterCoffee);
// Array can take any class that inherits from appliance
Appliance[] kitchenWare = new Appliance[2];
kitchenWare[0] = misterCoffee;
kitchenWare[1] = oldToasty;
// UPCAST: CoffeeMaker to Appliance
// When you have an appliance reference, you can ONLY access
// the methods and properties that have to do with appliances.
// You CAN'T use the CoffeeMaker methods and properties through
// an Appliance reference, even if you know it really is one.
Appliance powerConsumer = new CoffeeMaker();
powerConsumer.ConsumePower();
// DOWNCAST: Appliance to CoffeeMaker
// You can determine if the Appliance is a CoffeeMaker using `is`
// If so, you can downcast it back to access the CoffeeMaker
// properties & methods
if (powerConsumer is CoffeeMaker)
{
CoffeeMaker javaJoe = powerConsumer as CoffeeMaker;
javaJoe.MakeCoffee();
// In an incorrect downcast, the object returned is null, so `Preheat` will not be called
Oven foodWarmer = powerConsumer as Oven;
if (foodWarmer != null)
{
foodWarmer.Preheat();
}
}
// Three different references that point to the same object can
// acess different methods and properties, depending on the
// reference's type.
// Reference 1
Oven misterToasty = new Oven();
misterToasty.Preheat();
// Reference 2
ICooksFood cooker;
if (misterToasty is ICooksFood)
{
cooker = misterToasty as ICooksFood;
cooker.HeatUp();
}
// Reference 3
if (misterToasty is Appliance)
{
powerConsumer = misterToasty;
powerConsumer.ConsumePower();
}
}
static void Main(string[] args)
{
CoffeeMaker misterCoffee = new CoffeeMaker();
Oven oldToasty = new Oven();
// Method can take any class that inherits from appliance
MonitorPower(misterCoffee);
// Array can take any class that inherits from appliance
Appliance[] kitchenWare = new Appliance[2];
kitchenWare[0] = misterCoffee;
kitchenWare[1] = oldToasty;
// UPCAST: CoffeeMaker to Appliance
// When you have an appliance reference, you can ONLY access
// the methods and properties that have to do with appliances.
// You CAN'T use the CoffeeMaker methods and properties through
// an Appliance reference, even if you know it really is one.
Appliance powerConsumer = new CoffeeMaker();
powerConsumer.ConsumePower();
// DOWNCAST: Appliance to CoffeeMaker
// You can determine if the Appliance is a CoffeeMaker using `is`
// If so, you can downcast it back to access the CoffeeMaker
// properties & methods
if (powerConsumer is CoffeeMaker)
{
CoffeeMaker javaJoe = powerConsumer as CoffeeMaker;
javaJoe.MakeCoffee();
// In an incorrect downcast, the object returned is null, so `Preheat` will not be called
Oven foodWarmer = powerConsumer as Oven;
if (foodWarmer != null)
{
foodWarmer.Preheat();
}
}
// Three different references that point to the same object can
// acess different methods and properties, depending on the
// reference's type.
// Reference 1
Oven misterToasty = new Oven();
misterToasty.Preheat();
// Reference 2
ICooksFood cooker;
if (misterToasty is ICooksFood)
{
cooker = misterToasty as ICooksFood;
cooker.HeatUp();
}
// Reference 3
if (misterToasty is Appliance)
{
powerConsumer = misterToasty;
powerConsumer.ConsumePower();
}
}