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110 Microsoft Visual Studio 2010: A Beginner’s Guide
In .NET, the generic List type is declared as List<T>, or List(Of T) in VB. The T is a
type placeholder, where you can specify any type you want. For example, you could create
a List<int> for integers or a List<string> for strings, which would be List(Of Integer)
and List(Of String) in VB, respectively. In Listing 4-8, you can see that checkAccts is
declared as List<Checking> (List(Of Checking) in VB). Since a list grows dynamically
to accommodate any number of elements, you use the Add method to add elements to the
List. Once elements are in the List, you can use element access syntax, as shown in the for
loop, to access the elements one at a time. Collections such as List are convenient because
they have multiple convenience methods, such as Clear, Contains, Remove, and more.
In addition to List, the System.Collections.Generic namespace has several other
generic collections, such as Dictionary, Queue, and Stack. Each generic is initialized by
replacing the type parameters with the types you want to work on and then by using the
specialized methods of that collection. Whenever you see the type parameter syntax, you
should recognize that a generic is being used and you will have an idea of what the code
means and how to read it in the documentation.
Summary
What you learned in this chapter were essential skills for upcoming chapters in the
rest of the book. Knowing how delegates and events work helps you with event-driven
development that is common to GUI application development. Understanding interfaces
directly relates to being able to build Web services, among other uses. You’ll also make
regular usage of arrays and generics, and this chapter gave you the essentials to know
what collections are.
Remember that this was only an introduction to C# and VB and that there is much
more to learn about these languages. Of course, this book is about VS and not languages,
so the next chapter is where you’ll learn to build VS projects.