Microsoft 9GD00001 manual Coding Generics, 109, Listing 4-8 Coding a generic list collection

Chapter 4: Learning Just Enough C# and VB.NET: Intermediate Syntax 109

Coding Generics

Generics are language features that allow you to write a piece of code that will work with multiple types efficiently. A generic class definition has a placeholder for the type you want it to represent, and you use this placeholder to declare the type you want to work with. There is an entire library of generic collections in .NET as well as generic types across the entire .NET Framework Class library. Because of the volume of information required for comprehensive coverage of generics, this section will only serve as a brief introduction, giving you an example of generic use that you’re most likely to see in the future. Listing 4-8 demonstrates how to declare a generic List. The code specifies the type of the list as a Checking account and then proceeds to populate the generic list and perform operations on the Checking elements of the generic list. Remember to include a using directive (imports for VB) for the System.Collections.Generic namespace near the top within your file.

Listing 4-8 Coding a generic list collection

C#:

private void ListDemo()

{

List<Checking> checkAccts = new List<Checking>();

checkAccts.Add(new Checking()); checkAccts.Add(new Checking());

for (int i = 0; i < checkAccts.Count; i++)

{

Console.WriteLine(checkAccts[i].CurrentBalance);

}

}

VB:

Sub ListDemo()

Dim checkAccts As New List(Of Checking)

checkAccts.Add(New Checking()) checkAccts.Add(New Checking())

For i As Integer = 0 To checkAccts.Count - 1 Console.WriteLine(checkAccts(i).CurrentBalance)

Next

End Sub