Intellisense not showing the .Length, .Count methods-CodePudding

How can I check if item is null?

Dim list As New List(Of ContactU)
list = resource.ContactUs.ToList()
If list.Count <> 0 Then
    For Each item In list
        If item Then
            'Do the loop 
        End If
    Next
End If

CodePudding user response：

Your question title conflicts with your written question of "How can I check if item is null?" To answer that question, you check if the variable Is Nothing:

Dim list As List(Of ContactU) = resource.ContactUs.ToList()

If list Is Nothing Then
    ' Handle what happens when the list is Null/Nothing.
Else
    ' Handle what happens when the list is not Null/Nothing.
End If

When checking if a variable is not Null/Nothing, the keyword is as follows (IsNot being one keyword):

If list IsNot Nothing Then

If you want to check that a variable IsNot Nothing and in the same statement check a property of the variable, you have to use the short-circuiting version of And or Or:

If list IsNot Nothing AndAlso list.Count > 0 Then

This way, if list is Nothing, the list.Count will not get evaluated, and will not throw a null reference exception.