Le Blog De La L'Ernestas && Vampyro fermerio Ernesto blogis

Simple example with interfaces. This example just shows, that when we have interface (method’s signatures, delegates etc.) we don’t care, how this interface is implemented.

We have interface and class:

interface IList
{
void Add(object o);
void Remove(object o);
void Print();
}

class Implementation : IList
{
private ArrayList arrayList = new ArrayList();

public void Add(object o)
{
arrayList.Add(o);
}

public void Remove(object o)
{
arrayList.Remove(o);
}

public void Print()
{
foreach (string line in arrayList)
Console.WriteLine(line);
}

}

Somewhere in the code we have methods:

void Foo(IList list)
{
list.Add(“I”);
list.Add(“am”);
list.Add(“using”);
list.Add(“interfaces”);
}

void Foo2(IList list)
{
list.Print();
}

And we call them:

IList list = new Implementation();
Foo(list);
Foo2(list);

Try to guess, what is the output?