For a combobox, selectedIndex returns 0 while selectedtext returns a value - vb.net

Question

Once I select a value from a Combobox and save the form, ComboBox.SelectedText contains the value selected but ComboBox.SelectedIndex is returning 0 always for each item in the list. Below is just a sample code for reference.
If (combobox1.SelectedIndex = 0 Or combobox1.SelectedText = "")
MessageBox.Show("No value selected")
else
MessageBox.Show("Some value selected")
End If

Answer 1

Some code to illustrate usage
Private Sub ComboBox1_SelectedIndexChanged(sender As Object,
e As EventArgs) Handles ComboBox1.SelectedIndexChanged
'check for no item selected
If ComboBox1.SelectedIndex < 0 Then
Stop 'no item
Else
Dim idx As Integer = ComboBox1.SelectedIndex
Dim val As String = CStr(ComboBox1.SelectedItem) '<-- use SelectedItem
Stop
End If
End Sub

Answer 2

Small Answer
SelectedText is not the same as SelectedItem. Take a look at ComboBox.SelectedText:
Gets or sets the text that is selected in the editable portion of a ComboBox.
I think that you are confusing this with ComboBox.SelectedItem
SelectedIndex: -1 if nothing selected, otherwise the index of the selected item
SelectedValue: null if nothing selected, otherwise the selected item
SelectedText: the text that the operator marked in the editable part of the combo box.
** Room for improvement **
You use VB. My VB is a bit rusty, so I'll give my answer in C#. I guess you'll get the gist.
In Winforms, whenever you want to fill a that shows a sequence of items, like ComboBoxes, ListBoxes, DataGridViews, Charts, etc, there are usually two methods:
Fill the ComboBox one by one with the texts that you want to display
Use a DataSource: fill it with the Items that you want to be selectable, and tell the ComboBox which property of the selectable items you want to display.
Use the first method if you only want to display a constant array of strings. Fill ComboBox.Items. When an item is selected, use SelectedIndex to get the index of the selected string. Use ComboBox.Items[selectedIndex] to get the selected string.
If the string represents something more than just a string, for instance the text represents a Customer, or a Product. It is usually easier to use the DataSource method.
To do that, you use property ComboBox.DataSource to tell the ComboBox which Customersit should display. In ComboBox.ValueMember you tell the ComboBox which Customer poperty should be used to represent the Customer, for instance the name of the Customer.
Once the operator selected the name of the Customer, you get the complete Selected Customer using property ComboBox.SelectedItem:
List<Customer> availableCustomers = ...
ComboBox combo1 = new ComboBox(...);
combo1.ValueMember = nameof(Customer.Name); // the Customer property that you want to display
combo1.DataSource = availableCustomers;
After the operator selected an item, you can process the event, and fetch the selected customer immediately:
Customer selectedCustomer = (Customer)cmbo1.SelectedValue;
ProcessSelectedCustomer(selectedCustomer);
Of course you should only select a property that is unique. If you have two Customers named "Hans Brinker", operators wouldn't know which name represents which Customer.
Apart from the nice thing that you don't have to do a lookup from SelectedIndex to what this selected item represents (a Customer), you are independent of the order in which the Customers are displayed.
Another nice thing: if in future versions you want to change from ComboBox to ListBox, or maybe even to DataGridView, you won't have to change your model drastically: the control still shows a sequence of Customers, and once an operator selects something that represents this Customer (Name? Id?, DataGridView Row?), you get the complete Customer.

Answer 3

(1)ComboBox1.SelectedIndex starts from -1, when you are not selected, ComboBox1.SelectedIndex=-1
(2)When you click combobox1.items, SelectedText is always "".
This is because, at the time of these events(SelectedIndexChanged, SelectedValueChanged.. ), the previous SelectedText value has been cleared and the new value has not yet been set. You can use the SelectedItem property instead.
E.g:combobox1.SelectedItem
Please try the following code.
If ComboBox1.SelectedIndex = -1 Then
MessageBox.Show("No value selected")
Else
MessageBox.Show("Some value selected")
End If