vb.net - My.Settings 不保存变量

Question

我有以下代码：

Imports System.IO

Public Class Form2

Dim strInitialDirectory As String
Dim strInitialFile As String
Const strDefaultFileDirectory As String = "C:\Users\Sam\Desktop\Visual Basic\Test"
Const strDefaultFileName As String = "\test.txt"
Dim strFileJPath1 As String = strInitialDirectory + strInitialFile
Dim strFileJPath2 As String = strDefaultFileDirectory + strDefaultFileName

Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    If My.Settings.strInitialDirectory = Nothing Or My.Settings.strInitialFile = Nothing Then
        My.Settings.strInitialDirectory = strDefaultFileDirectory
        My.Settings.strInitialFile = strDefaultFileName
    Else
        MsgBox("Else executed") ' debug 
        strInitialDirectory = strDefaultFileDirectory
        strInitialFile = strDefaultFileName
        strInitialDirectory = My.Settings.strInitialDirectory
        strInitialFile = My.Settings.strInitialFile
    End If
End Sub
End Class

基本上，当表单加载时，我希望它检查 My.Settings 中是否有任何内容，如果没有，请将值设置为默认值，但是在再次打开程序时，它不会执行 else 语句，让我相信我做错了什么并且设置没有保存。对此有任何意见吗？谢谢。

Answer 1

您必须在 My.Settings 中调用保存功能

My.Settings.Save()

您应该在更新设置函数的末尾添加它。这将保存下一个会话的所有设置。

下面是一个 UpdateSettings 函数的示例：

Private Sub UpdateSettings()

    Console.WriteLine("Saving Settings")

    My.Settings.WO_imprevu = CheckBoxImprevu.Checked
    My.Settings.WO_prevu = CheckBoxPrevu.Checked
    My.Settings.Date_type = ComboBoxDateType.SelectedIndex
    My.Settings.Date_debut = DateTimePickerDebut.Value

    My.Settings.Save()

    Console.WriteLine("Settings Saved")
End Sub

Answer 2

尝试使用String.IsNullOrWhiteSpace()而不是= Nothing.

将您的子更改为：

Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    If String.IsNullOrWhiteSpace(My.Settings.strInitialDirectory) OrElse String.IsNullOrWhiteSpace(My.Settings.strInitialFile) Then
        My.Settings.strInitialDirectory = strDefaultFileDirectory
        My.Settings.strInitialFile = strDefaultFileName
    Else
        MsgBox("Else executed") ' debug 
        strInitialDirectory = strDefaultFileDirectory
        strInitialFile = strDefaultFileName
        strInitialDirectory = My.Settings.strInitialDirectory
        strInitialFile = My.Settings.strInitialFile
    End If
End Sub