Remove line from text file which listed in list box - vb.net

Question

I have a text file(its hosts file)
I can add lines(domains) to the file through a text box.
When i click the 'Save' button, inputted value(domain) saves to the text(hosts) file with a 127.0.0.1 prefix. At the same time it shows that in a list box too(while showing it in list box, it won't show the prefix(127.0.0.1). It'll only show the value got from the text field)
What i need now is that,
When i click and select an item from the list box and press 'Remove' button, it needs to be removed from both the list box and the text(hosts) file.
Also, while removing the selected item from the list box, the prefix(127.0.0.1) also should be removed from the file without leaving an empty line.
Private Sub Button6_Click(sender As Object, e As EventArgs) Handles BtnCustomDomainremove.Click
ListBox1.Items.Remove(ListBox1.SelectedItem)
Dim delLine As Integer = 1
Dim lines As List(Of String) = System.IO.File.ReadAllLines("C:\Windows\System32\drivers\etc\hosts").ToList
lines.RemoveAt(delLine - 1)
System.IO.File.WriteAllLines("C:\Windows\System32\drivers\etc\hosts", lines)
MessageBox.Show("URL removed from Block List !", "Custom Block List")
End Sub
Above code it removes the top value from file and selected one from list box.

Answer 1

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim lines As List(Of String) = System.IO.File.ReadAllLines("C:\Windows\System32\drivers\etc\hosts").ToList
Dim Findstring = IO.File.ReadAllText("C:\Windows\System32\drivers\etc\hosts")
Dim Lookfor As String = CStr("127.0.0.1" + ListBox1.SelectedItem)
If lines.Contains(Lookfor) Then
For i = 0 To Findstring.Length - 1
lines.Remove(Lookfor)
Next
System.IO.File.WriteAllLines("C:\Windows\System32\drivers\etc\hosts", lines)
ListBox1.Items.Remove(ListBox1.SelectedItem)
MessageBox.Show("URL removed from Block List !", "Custom Block List")
Else
MsgBox("string not found")
End If
End Sub
This code works for me, you might have to tweak it slightly to match your prefereneces however, it seems to find each occurunce (if there's more than one) of the selected item in listbox1 (if there's only one occurance you can remove the for loop.

Answer 2

Instead of Reading and Writing the file on every change to the list, save the list when the form closes. Read the file when the form opens and populate the list. While the form is open just add and remove list items as you normally would.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim path = "C:\Windows\System32\drivers\etc\hosts.txt"
Dim lines() As String = File.ReadAllLines(path)
'Substring(9) the characters in "127.0.0.1" are index 0-8 so we begin with index 9
'and return the rest of the string.
Dim TrimmedList = From line In lines
Select line.Substring(9)
For Each item In TrimmedList
ListBox2.Items.Add(item)
Next
End Sub
Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
Dim sb As New StringBuilder()
For Each item In ListBox2.Items
sb.AppendLine("127.0.0.1" & item.ToString)
Next
Dim path = "C:\Windows\System32\drivers\etc\hosts.txt"
File.WriteAllText(path, sb.ToString)
End Sub
Requires
Imports System.IO
Imports System.Text

Answer 3

try this code
Private Sub Button6_Click(sender As Object, e As EventArgs) Handles BtnCustomDomainremove.Click
ListBox1.Items.Remove(ListBox1.SelectedItem)
Dim details As String = ""
For Each o As Object In ListBox1.Items
details += o.ToString + vbNewLine
Next
My.Computer.FileSystem.WriteAllText("C:\Windows\System32\drivers\etc\hosts", details, False)
MessageBox.Show("URL removed from Block List !", "Custom Block List")
End Sub