從工作線程引發事件Vb.net

Question

我正在尋找vb.net的控制台應用程序。 我試圖讓一個工作線程向主線程引發一個事件，以便在屏幕上顯示數據（每當工作線程完成一個循環時，單詞“ HIT”）。 我的代碼如下。

我不確定為什么，但是主線程的Private Sub CounterClass_GivingUpdate() Handles _counter.AboutToDistributeNewupdate沒有執行。

Imports System.Threading

Module Module1

    Private WithEvents _counter As CounterClass
    Private trd As Thread
    Sub Main()
        While True

            Dim s As String = Console.ReadLine()
            Dim started As Boolean
            Select Case s
                Case "status"
                    WriteStatusToConsole("You typed status")
                Case "startcounter"
                    If started = False Then
                        starttheThread()
                        started = True
                        WriteStatusToConsole("You Have Started The Timer")
                    Else
                        WriteStatusToConsole("YOU HAVE ALREADY STARTED THE TIMER!!!")
                    End If

            End Select
        End While

    End Sub


    Private Sub CounterClass_GivingUpdate() Handles _counter.AboutToDistributeNewupdate
        WriteStatusToConsole("Hit")
    End Sub

    Private Sub starttheThread()
        Dim c As New CounterClass
        trd = New Thread(AddressOf c.startProcess)
        trd.Start()
    End Sub
    Sub WriteStatusToConsole(ByVal stringToDisplay As String)
        Console.WriteLine(stringToDisplay)
    End Sub
End Module

Public Class CounterClass
    Public Event AboutToDistributeNewupdate()
    Public Sub sendStatusUpdateEvent(ByVal updatestatus As String)
        RaiseEvent AboutToDistributeNewupdate()
    End Sub

    Public Sub startProcess()
        Dim i As Int64
        Do
            Thread.Sleep(1000)
            i = i + 1
            sendStatusUpdateEvent(i.ToString)
        Loop
    End Sub

End Class

Answer 1

您的CounterClass_GivingUpdate()僅處理_counter變量的事件（您不使用的變量！） 。 每次您聲明新的CounterClass它都有它自己引發的事件的實例。

您知道有兩種選擇：

• 選項1

  為您創建的每個新CounterClass實例訂閱事件。 意味着每次創建類的新實例時，都必須使用AddHandler語句：

   Private Sub starttheThread() Dim c As New CounterClass AddHandler c.AboutToDistributeNewupdate, AddressOf CounterClass_GivingUpdate trd = New Thread(AddressOf c.startProcess) trd.Start() End Sub 

• 選項2

  將事件標記為“ Shared以使其可用，而無需創建該類的實例。 為此，還必須通過在方法Main()訂閱事件來更改訂閱事件的方式：

   Sub Main() AddHandler CounterClass.AboutToDistributeNewupdate, AddressOf CounterClass_GivingUpdate ...the rest of your code... End Sub Private Sub CounterClass_GivingUpdate() 'No "Handles"-statement here. WriteStatusToConsole("Hit") End Sub Public Class CounterClass Public Shared Event AboutToDistributeNewupdate() 'Added the "Shared" keyword. ...the rest of your code... End Class