vb.net多线程

Public Class Form1

    Dim myThread As Threading.Thread
    Dim myThread2 As Threading.Thread

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

        myThread = New Threading.Thread(AddressOf RunSub)
        myThread.Start()
    End Sub

    '带参数线程
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        myThread2 = New Threading.Thread(New Threading.ParameterizedThreadStart(AddressOf RunSub2))
        myThread2.Start(")
    End Sub
    Private Sub RunSub()
        Dim i As Integer
        Dim j As Integer =
        For i =  To
            j += j
        Next
        ShowMessage(j.ToString)
    End Sub

    Private Sub RunSub2(ByVal val As String)
        ShowMessage(val)
    End Sub

    Public Delegate Sub ShowMessageDelegate(ByVal msg As String)
    Private Sub ShowMessage(ByVal msg As String)
        Dim ShowMessage As ShowMessageDelegate = New ShowMessageDelegate(AddressOf ShowMessageInvoke)
        Invoke(ShowMessage, New Object() {msg})

    End Sub

    Private Sub ShowMessageInvoke(ByVal msg As String)
        TextBox1.Text = msg
    End Sub

End Class