VB.NET Advanced Topics

This section delves into more sophisticated aspects of Visual Basic .NET programming, empowering you to build robust, high-performance, and scalable applications.

Asynchronous Programming (Async/Await)

Learn how to write non-blocking code with the Async and Await keywords, improving application responsiveness, especially for I/O-bound operations.

Key Concepts:

The Task and Task(Of TResult) types
AsyncVoid anti-pattern
Handling exceptions in asynchronous methods
ConfigureAwait


Public Async Function GetDataAsync(url As String) As Task(Of String)
    Using client As New HttpClient()
        Dim response As HttpResponseMessage = Await client.GetAsync(url)
        response.EnsureSuccessStatusCode() ' Throw if not successful
        Dim responseBody As String = Await response.Content.ReadAsStringAsync()
        Return responseBody
    End Using
End Function

Expression-Bodied Members

A concise syntax for defining members that consist of a single expression, leading to cleaner and more readable code.


Public Class Person
    Public Property Name As String

    ' Constructor
    Public Sub New(name As String)
        Me.Name = name
    End Sub

    ' Expression-bodied property
    Public ReadOnly Property Greeting As String
        Get
            Return $"Hello, my name is {Name}."
        End Get
    End Property

    ' Expression-bodied method
    Public Function GetLengthOfName() As Integer => Name.Length
End Class

Pattern Matching

A powerful feature for inspecting the structure of data and executing code based on that structure. This includes Is expressions and Case statements with pattern matching.

Type patterns
Constant patterns
Var patterns
Property patterns
Recursive patterns


Public Function ProcessItem(item As Object) As String
    Return Type Of item
        Case Is Integer i
            Return $"It's an integer: {i * 2}"
        Case Is String s
            Return $"It's a string with length {s.Length}"
        Case Else
            Return "Unknown type"
    End Type
End Function

Nullable Reference Types

Improve code safety by explicitly indicating whether a reference type can be null, helping to prevent NullReferenceException at compile time.

Enabling nullable reference types
Non-nullable by default
The ? operator
The null-forgiving operator (!)