vb.net “你调用的对象是空的？”
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"Object reference not set to an instance of an object?"
提问by user2221877
Trying to show other form if textbox's text is correct. When I debug I get an error saying "Object reference not set to an instance of an object". The code is below:
如果文本框的文本正确，则尝试显示其他形式。当我调试时，我收到一条错误消息，提示“对象引用未设置为对象的实例”。代码如下：
'OK is OK button, MainForm is the form I'm trying to open
Private Sub OK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OK.Click
Dim pass As String = My.Computer.FileSystem.ReadAllText("password.txt")
If PasswordTextBox.Text = pass Then
MainForm.Owner = Me
Me.Hide()
'"Object reference not set to an instance of an object" error when debugging on line below
MainForm.Show()
End If
End Sub
回答by Jeremy
You need to create a new instance of the form you want to display. You do this by creating a variable of form T and then showing it.
您需要创建要显示的表单的新实例。为此，您可以创建一个 T 形式的变量，然后显示它。
If you don't create an instance of your form the MainForm.Show()code will be invoking Show()on an null reference.
如果您不创建表单的实例，则MainForm.Show()代码将调用Show()空引用。
If PasswordTextBox.Text = pass Then
Me.Hide()
Dim theFormIWantToShow As New MainForm
theFormIWantToShow.Show()
End If
