Question

我有一个这样的脚本，一旦用户点击radiobutton，就会出现消息框。但是当我点击da＆＃34; No＆＃34; dialogresult，messagebox出现两次。我不知道为什么会这样。我不希望它显示两次。我知道必须有一个如此简单的方法来解决这个问题。＆GT;＆GT;我也试图返回功能，但没有运气。

 Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object,      ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
         Dim result As Integer = MessageBox.Show("message", "caption",      MessageBoxButtons.YesNo)
         If result = DialogResult.No Then
             RadioButton1.Checked = False
         ElseIf result = DialogResult.Yes Then
             memoryh4x(&H160ED98, 1, 4)
         End If
     End Sub

Answer 1

您更改了RadioButton Checked属性，这会导致第二次调用事件处理程序。

避免重新进入事件处理程序的最简单方法是通过全局变量

Dim inCheckedChanged As Boolean = False
......

Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object,      ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
     Try
        ' If we could display the message box..... 
        if inCheckedChanged = False then
           ' Block the reexecution of the MessageBox when clicking NO
            inCheckedChanged = True
            Dim result As Integer = MessageBox.Show("message", "caption",      MessageBoxButtons.YesNo)
            If result = DialogResult.No Then
                ' Now, changing the property reenters the event handler 
                ' but the global variable prevents to get a second messagebox
                RadioButton1.Checked = False
            ElseIf result = DialogResult.Yes Then
                memoryh4x(&H160ED98, 1, 4)
            End If
         End If
    Finally
         InCheckedChanged = False
    End Try
 End Sub

请注意，我将所有内容放在Try / Finally块中。这样，如果某个东西抛出异常，全局变量InCheckedChanged在退出事件处理程序之前总是被重置为false

MsgBox出现多次

1 个答案: