Question

I’m a Java programmer learning C# these days.

Usually in Java when using lists, it should be preferrable programming against its interface in order to switch between implementations:

List<Object> list = new ArrayList<Object>();
//or
list = new LinkedList<Object>(); 

What about C# ? Does exist a similar approach? Can someone show me an example? Since now I’m building a list this way, but I don’t think List is an interface:

List<int> list = new List<int>();
list.Add(2);

Answer 1

In .NET it is also preferable to work with the highest possible object in the hierarchy. You could use the IList<T> interface:

IList<int> list = new List<int>();
list.Add(2);

And if you don’t need to access the list by index you could also use the ICollection<T> interface which is even higher in the hierarchy.

Or if you only want to enumerate through the list you could use the highest possible interface which is IEnumerable<T>:

IEnumerable<int> list = new List<int>(new[] { 1, 2, 3 });
foreach(int item in list)
{
    ...
}