VB.NET navigate to a specific ListBox item

Question

I have a listbox that I load items into. Each line starts with time in HH:mm:ss format. I want a button such that on the click of it, the listbox selected item would navigate to a line that starts with a particular time, as entered into a textbox by the user. Secondly, I have a textbox that copies the first 5 characters of the selecteditem, using selecteditem.text.tostring.substring(0,5). Now, I need to capture the first 5 characters of the line RIGHT BELOW the selected item. Thanks for helping.

Answer 1

ListBox1.SelectedIndex = 2

0 equal first line
1 equal second line
2 equal third line
and finish like that

or you can add -1 in the end like this below

ListBox1.SelectedIndex = 2 - 1

so you can select the actual line number two

Answer 2

Using the ListBox's FindString() method you can find the index of the first item starting with the specified string. You can then use that to set the SelectedIndex property which will select the item at the specified index.

To get the item below the currenty selected one you just have to get SelectedIndex + 1 from the Items collection.

Public Sub DoSomething()
    Dim Index As Integer = ListBox1.FindString(TextBox1.Text) 'Find the index of the item starting with whatever is in TextBox1.
    If Index > -1 Then 'Check if the item exists/was found.
        ListBox1.SelectedIndex = Index
        TextBox2.Text = ListBox1.Items(Index).ToString().Substring(0, 5)

        If Index < ListBox1.Items.Count - 1 Then 'Check if the found item is the last item or not.
            TextBox3.Text = ListBox1.Items(Index + 1).ToString().SubString(0, 5)
        Else 'This was the last item.
            MessageBox.Show("You've reached the end of the list.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
        End If

    Else 'No item was found.
        MessageBox.Show("No item found starting with the specified text!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
    End If
End Sub