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| Title | Load a ListBox from a text file in VB .NET, skipping blank lines |
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| Keywords | VB.NET, NET, ListBox, text file, load, initialize, blank lines, blanks |
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| Categories | VB.NET, Controls |
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The program creates a StreamReader to read a text file containing a list of choices. It uses the reader's ReadLine method to read the file's contents one line at a time. The program trims off any blank spaces from each line and, if the line isn't blank, adds it to the ListBox.
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' Load the ListBox from a file.
Private Sub Form1_Load(ByVal sender As System.Object, ByVal _
e As System.EventArgs) Handles MyBase.Load
Try
Dim file_name As String = DataFile()
Dim stream_reader As New IO.StreamReader(file_name)
Dim line As String
' Read the file one line at a time.
line = stream_reader.ReadLine()
Do While Not (line Is Nothing)
' Trim and make sure the line isn't blank.
line = line.Trim()
If line.Length > 0 Then _
lstAnimals.Items.Add(line)
' Get the next line.
line = stream_reader.ReadLine()
Loop
lstAnimals.SelectedIndex = 0
stream_reader.Close()
Catch exc As Exception
' Report all errors.
MsgBox(exc.Message, MsgBoxStyle.Exclamation, "Read " & _
"Error")
End Try
End Sub
' Return the data file name.
Private Function DataFile() As String
Dim file_name As String = Application.StartupPath
If file_name.EndsWith("\bin") Then file_name = _
file_name.Remove(file_name.Length - 4, 4)
file_name &= "\animals.txt"
Return file_name
End Function
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Alternatively you could grab the file all at once using the ReadToEnd method, use Split, and the loop through the resulting array adding the lines that were non-blank. That might be slightly faster because it does the file read all at once.
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