用VB2005写演示从子线程更新主线程数据遇到的问题
用VB2005写的从子线程更新主线程数据的程序,在启动调试时出现以下问题:
在 System.NullReferenceException 中第一次偶然出现的“如何从子线程更新主线程数据.exe”类型的异常
在 System.InvalidOperationException 中第一次偶然出现的“System.Windows.Forms.dll”类型的异常
那是什么原因?
哪位高人给指点指点。
全部代码如下:
Imports System.Threading'命名空间声明
Public Class Form1
Public MyThread As Thread
'从子线程更新进度条数据
Public Sub UpDateProgress()
Dim i As Integer
Dim Myvalue As Integer
Dim St As String
St = "当前模拟执行进度完成百分比:"
For i = 1 To 100 Step 1
Thread.Sleep(50)
Myvalue = i
Me.ProgressBar1.Value = Myvalue
Me.Label1.Text = St + Myvalue.ToString() + "%"
Next
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim MyDelegate As New ThreadStart(AddressOf UpDateProgress)
Dim MyThread As New Thread(MyDelegate)
MyThread.Start()
End Sub
End Class