vb.net My.Settings 不保存变量
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My.Settings not saving variables
提问by
I have the following code:
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
Basically, when the form loads I'd like it to check if there is anything in My.Settings and if not, set the values to the defaults, however upon opening the program again, it does not execute the else statement, leaving me to believe I'm doing something wrong and the settings aren't saving. Any input into this? Thanks.
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，将值设置为默认值，但是再次打开程序时，它不会执行 else 语句，让我去相信我做错了什么并且设置没有保存。对此有何意见？谢谢。
采纳答案by char1es
You have to call the save function in My.Settings
您必须在 My.Settings 中调用保存功能
My.Settings.Save()
You should add this at the end of an update settings function. This will save all the settings for the next session.
您应该在更新设置功能的末尾添加它。这将保存下一个会话的所有设置。
Here us an example of an UpdateSettings function:
下面是一个 UpdateSettings 函数的例子：
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
回答by Alsace
Try using String.IsNullOrWhiteSpace()instead of = Nothing.
尝试使用String.IsNullOrWhiteSpace()而不是= Nothing.
Change your sub to this:
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
