Define Thread

Question

Hello,

In this code:

Dim ThreadBlah As New Thread(AddressOf BlahThread)
vs
Dim ThreadBlah As New Thread(New ParameterizedThreadStart(AddressOf BlahThread))
ThreadBlah.Start
Private Sub BlahThread(ByVal InParam As Object)
...
End Sub

I can define ThreadBlah in 2 ways, both work:

Dim ThreadBlah As New Thread(AddressOf BlahThread)
vs
Dim ThreadBlah As New Thread(New ParameterizedThreadStart(AddressOf BlahThread))

Are both valid? The first one works although it does not state the Parameterized.

Thanks.

Answer 1

If the Visual Studio is properly configured for step-by-step debugging, you will see that both of New Thread execute the same constructor that takes a ParameterizedThreadStart. Therefore the statements are equivalent. The compiler selects the appropriate constructor in both cases.

However, ThreadBlah.Start(...) should include an argument that will be passed to InParam.

Answer 2

the .net automatic type casting is why the second works. the Thread constructor has two delegates:

• void method with no parameters
• void method with one object parameter

if you pass the address of a method, type casting determine which delegate overload to use.

Answer 3

Here is another approach to this using Tasks instead of Threads...

Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    BlahTask = Task.Run(Sub()

                            BlahActionString("TEST")

                        End Sub)

    Await BlahTask

    BlahTask = Task.Run(Sub()

                            BlahActionInteger(42)

                        End Sub)

    Await BlahTask

End Sub

Dim BlahTask As Task

Dim BlahActionString As Action(Of String) = Sub(S As String)

                                                BlahThread(S)

                                            End Sub

Dim BlahActionInteger As Action(Of Integer) = Sub(I As Integer)

                                                  BlahThread(I)

                                              End Sub

Private Sub BlahThread(ByVal InParam As Object)

    ' blah, blah

    Debug.WriteLine(InParam.ToString)

End Sub