如何在VB.NET中使用IsNullOrEmpty？

Question

Why doesn't the following compile in VB.NET?

Dim strTest As String
If (strTest.IsNullOrEmpty) Then
   MessageBox.Show("NULL OR EMPTY")
End if

Answer 1

IsNullOrEmpty是'共享'所以你应该这样使用它：

If String.IsNullOrEmpty(strTest) Then

Answer 2

You can actually just compare to an empty string:

If strTest = "" Then
    MessageBox.Show("NULL OR EMPTY")
End If

Answer 3

String.IsNullOrEmpty is a shared (or static, in C#) method.

Dim strTest As String
If (String.IsNullOrEmpty(strTest)) Then
   MessageBox.Show("NULL OR EMPTY")
End if