如何在 vb.net 中一次运行两个进程？

Question

 Imports System.Threading.Thread
 Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim i As Integer
    While i <= 10
        TextBox1.Text = i.ToString()
        TextBox1.Refresh()
        Sleep(1000)
        i = i + 1
    End While
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    Dim lbl As Label
    Dim matches() As Control
    matches = Me.Controls.Find("Label" & TextBox1.Text, True)
    If matches.Length > 0 AndAlso TypeOf matches(0) Is Label Then
        lbl = DirectCast(matches(0), Label)
        lbl.BackColor = Color.Yellow
    End If
End Sub
End Class

如果我单击 button1，那么它会在一秒钟后在文本框中显示 1 到 10。它工作正常。当 textbox.text=2 时单击 button1 后，我想按下 button2。如果我按下按钮 2，那么它应该显示 label2.backcolor=yellow。标签号是 textbox.text。问题是：在button1中完成while循环后，只有我可以按下button2。完成 while 循环后，我们只得到黄色的 label10。解决方案：我想在结束while循环之前点击那个button2。请给出解决方案。其实我想在 textbox1.text 中显示哪个数字，该标签应该是黄色的。

Answer 1

Button1.Click 中的 While 循环阻塞了 UI 线程，因此阻塞了 Button2.Click 处理程序，直到 Button1.Click 完成。一种简单的解决方案是制作Button1.ClickAsync（假设.NET 4.5+）并改用Task.Delay(1000)：

Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim i As Integer
    While i <= 10
        TextBox1.Text = i.ToString()
        TextBox1.Refresh()
        'Sleep(1000)
        Await Task.Delay(1000)
        i = i + 1
    End While
End Sub

这将在Await 被点击时释放 UI 线程。

您也可以使用后台线程，但您必须确保您的 UI 更新发生在 UI 线程上。

Answer 2

警告：后面的代码很糟糕（但它有效！）

Private Sub Wait(ByVal time As Integer) 'in milliseconds
    Dim secs As Integer = Environment.TickCount
    While Environment.TickCount < secs + time
        Application.DoEvents()
    End While

End Sub
Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
    Dim i As Integer
    While i <= 10
        Label1.Text = i.ToString()
        Label1.Refresh()
        Wait(1000)
        i = i + 1
    End While
End Sub
Private Sub Button2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click
    Static toggle As Boolean
    If toggle Then
        Label1.BackColor = Color.Green
    Else
        Label1.BackColor = Color.Blue
    End If
    toggle = Not toggle
End Sub