I am trying to make a program that takes a text from a file and writes it into a label in visual studios 10. I want to be able to click buttons on the exe to make it go from the previous line to the next line and vise versa. I am storing the text into an array and then making the label equal the text on the given part of the array. I am receiving the error "Object reference not set to an instance of an object." Can anyone help ? thanks. here is part of my code my code:
Private Sub BrowseButton_Click(sender As System.Object, e As System.EventArgs) Handles BrowseButton.Click
Dim UserInput As DialogResult = Browser.ShowDialog()
If UserInput = Windows.Forms.DialogResult.Cancel Then
Return
End If
FileOpen(1, Browser.FileName, OpenMode.Input)
Do While Not EOF(1)
Input(1, InternalTextFile(Index))
Index += 1
Loop
FileClose(1)
Output1Text.Text = InternalTextFile(Index)
Output2Text.Text = InternalTextFile(Index + 1)
End Sub
The error arises On the line Input(1, InternalTextFile(Index))
Without seeing more code it's hard to tell, but if the error is on Input(1, InternalTextFile(Index)), its likely that the variable InternalTextFile was never assigned a value. Something like this maybe?
Dim InternalTextFile As New List(of String)
Dim reader As StreamReader = New StreamReader(Browser.FileName)
Try
Do
InternalTextFile.Add(reader.ReadLine)
Loop Until reader.Peek = -1
Finally
reader.Close()
End Try
It looks like maybe you want something like this:
Private Sub BrowseButton_Click(sender As System.Object, e As System.EventArgs) Handles BrowseButton.Click
If Browser.ShowDialog() = Windows.Forms.DialogResult.Cancel Then Exit Sub
Dim InternalTextFile() As String = File.ReadAllLines(Browser.FileName)
Output1Text.Text = InternalTextFile(InternalTextFile.Length - 2)
Output2Text.Text = InternalTextFile(InternalTextFile.Length - 1)
End Sub
Related
So, I am trying to develop a book database. I have created a table with 11 columns which populates a DGV, where only 6 columns are showed. The full data of each book is shown in a lower part of the form, where I have textboxes, which are bounded (BindingSource) to the table, that change as I move in the DGV.
Now, what I want to do is to have the posibility to export/import data from a file.
I have accomplished the exporting part with the following code:
Private Sub BtnExport_Click(sender As Object, e As EventArgs) Handles BtnExport.Click
Dim txt As String = String.Empty
For Each row As DataGridViewRow In DbdocsDataGridView.Rows
For Each cell As DataGridViewCell In row.Cells
'Add the Data rows.
txt += CStr(cell.Value & ","c)
Next
'Add new line.
txt += vbCr & vbLf
Next
Dim folderPath As String = "C:\CSV\"
File.WriteAllText(folderPath & "DataGridViewExport.txt", txt)
End Sub
However, I can't manage to import from the txt. What I've tried is this: https://1bestcsharp.blogspot.com/2018/04/vb.net-import-txt-file-text-to-datagridview.html
It works perfectly if you code the table and it populates de DGV without problem. I can't see how should I adapt that code to my need.
Private Sub BtnImport_Click(sender As Object, e As EventArgs) Handles BtnImport.Click
DbdocsDataGridView.DataSource = table
Dim filas() As String
Dim valores() As String
filas = File.ReadAllLines("C:\CSV\DataGridViewExport.txt")
For i As Integer = 0 To filas.Length - 1 Step +1
valores = filas(i).ToString().Split(",")
Dim row(valores.Length - 1) As String
For j As Integer = 0 To valores.Length - 1 Step +1
row(j) = valores(j).Trim()
Next j
table.Rows.Add(row)
Next i
End Sub
That is what I've tried so far, but I always have an exception arising.
Thanks in advance to anyone who can give me an insight about this.
The DataTable class has built-in methods to load/save data from/to XML called ReadXml and WriteXml. Take a look at example which uses the overload to preserve the schema:
Private ReadOnly dataGridViewExportPath As String = IO.Path.Combine("C:\", "CSV", "DataGridViewExport.txt")
Private Sub BtnExport_Click(sender As Object, e As EventArgs) Handles BtnExport.Click
table.WriteXml(path, XmlWriteMode.WriteSchema)
End Sub
Private Sub BtnImport_Click(sender As Object, e As EventArgs) Handles BtnImport.Click
table.ReadXml(path)
End Sub
While users can manually edit the XML file that is generated from WriteXML, I would certainly not suggest it.
This is code which writes to a text file:
speichern means to save.
Note that I use a # in my example for formatting reasons. When reading in again, you can find the # and then you know that and that line is coming...
And I used Private ReadOnly Deu As New System.Globalization.CultureInfo("de-DE") to format the Date into German format, but you can decide yourself if you want that. 🙂
Note that I'm using a FileDialog that I downloaded from Visual Studio's own NuGet package manager.
Private Sub Button_speichern_Click(sender As Object, e As EventArgs) Handles Button_speichern.Click
speichern()
End Sub
Private Sub speichern()
'-------------------------------------------------------------------------------------------------------------
' User can choose where to save the text file and the program will save it .
'-------------------------------------------------------------------------------------------------------------
Dim Path As String
Using SFD1 As New CommonSaveFileDialog
SFD1.Title = "store data in a text file"
SFD1.Filters.Add(New CommonFileDialogFilter("Textdatei", ".txt"))
SFD1.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
If SFD1.ShowDialog() = CommonFileDialogResult.Ok Then
Path = SFD1.FileName & ".txt"
Else
Return
End If
End Using
Using textfile As System.IO.StreamWriter = My.Computer.FileSystem.OpenTextFileWriter(Path, True, System.Text.Encoding.UTF8)
textfile.WriteLine("Timestamp of this file [dd.mm.yyyy hh:mm:ss]: " & Date.Now.ToString("G", Deu) & NewLine & NewLine) 'supposed to be line break + 2 blank lines :-)
textfile.WriteLine("your text")
textfile.WriteLine("#") 'Marker
textfile.Close()
End Using
End Sub
Private Sub FormMain_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
speichern()
End Sub
And this is to read from a text file:
'read all Text
Dim RAT() As String = System.IO.File.ReadAllLines(Pfad, System.Text.Encoding.UTF8)
If RAT.Length = 0 Then Return Nothing
For i As Integer = 0 To RAT.Length - 1 Step 1
If RAT(i) = "#" OrElse RAT(i) = "" Then Continue For
'do your work here with (RAT(i))
Next
Here is my code :
I'm trying to have some value out from a TXT file to a combobox or label but i feel combobox would be easier.
here's my code :
please note, some config.txt will only have 1 value while other 5-6
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim IDinFile As String
Dim ID As String
If IO.File.Exists("config.txt") Then
Using StreamReader As New IO.StreamReader("config.txt")
Do
IDinFile = StreamReader.ReadLine
If (IDinFile.IndexOf("7656")) <> -1 Then
ID = IDinFile.Substring(2)
ID = ID.Trim().Remove(ID.Length - 1)
ComboBox1.Items.Add(ID)
Exit Do
End If
Loop Until IDinFile Is Nothing
End Using
End If
End Sub
the file here in .png :
https://i.stack.imgur.com/iYaqP.png
Re-written the code for you. Problem was wrongly placed Exit Do. Also, its advisable to check the line before entering the loop rather than at the end of the loop.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim IDinFile As String
Dim ID As String
Const FILENAME As String = "config.txt"
If IO.File.Exists(FILENAME) Then
Using StreamReader As New IO.StreamReader(FILENAME)
Do While StreamReader.Peek() >= 0
IDinFile = StreamReader.ReadLine.Trim()
If (IDinFile.IndexOf("7656")) <> -1 Then
ID = IDinFile.Substring(1, IDinFile.Length - 2)
ComboBox1.Items.Add(ID)
End If
Loop
End Using
End If
End Sub
After you add the first item to the combobox you have an Exit Do statement. It no longer continues checking further lines and adding them to the combobox.
You should remove that statement.
Try this. It'll work if the values are organized line by line in the txt file.
Dim srd as New StreamReader("config.txt")
If io.file.exists("config.txt") then
Dim str() = srd.ReadToEnd.split(environment.newline)
For i = 0 to str.count-1
Combobox.item.add(str(i))
Next
srd.close
What I want to do is import a CSV file (called fwlist.txt), that looks like this:
modelname,power type,pic,part number,firmware, option1, option 1, etc
End result, i would like a combobox that shows the modelname, and when the model name is selected from the pulldown, it updates various labels and text boxes on the form with other information.
Here's what I have so far:
Dim filename As String = "fwlist.txt"
Dim pwrtype As String
Dim pic As String
Dim partnum As String
Dim lineread As String
Dim FirmwareName As String
Private Sub ReadFirmwaresLoad(sender As Object, e As EventArgs) Handles Me.Load
' Load the items into the NameComboBox list.
Dim ResponseDialogResult As DialogResult
Try
Dim FirmwareStreamReader As StreamReader = New StreamReader(filename)
' Read all the elements into the list.
Do Until FirmwareStreamReader.Peek = -1
lineread = FirmwareStreamReader.ReadLine()
Dim fields As String() = lineread.Split(",")
FirmwareName = fields(0) 'Take First Field
cbFW.Items.Add(FirmwareName)
'Set Text labels based on position in line.
pwrtype = fields(1)
pic = fields(2)
partnum = fields(3)
(...etc through options)
Loop
' Close the file.
FirmwareStreamReader.Close()
Catch ex As Exception
' File missing.
ResponseDialogResult = MessageBox.Show("File not Found!", "File Not Found",
MessageBoxButtons.OK, MessageBoxIcon.Question)
If ResponseDialogResult = DialogResult.OK Then
' Exit the program.
Me.Close()
End If
End Try
End Sub
Private Sub cbFW_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbFW.SelectedIndexChanged
lblPwrType.Text = pwrtype
lblPic.Text = pic
lblPartNum.Text = parnum
....etc thruogh options
End Sub
This code works, but only sort of. If i select anything from the combo box, it only gives me the information from the very last line of the CSV file - even if its the first entry in the box. I'm pretty sure it's something simple that I'm messing up.. anyone help?
First we read the lines into Firmware objects then we set this List(Of Firmware) as the DataSource of the ComboBox.
Then we handle the SelectedIndexChanged event of the ComboBox which will get the currently selected firmware and loads its data to the TextBox controls.
This is a tested, working example below:
Public Class Firmware
Public Property ModelName As String
Public Property PowerType As String
Public Property Pic As String
Public Property PartNumber As String
Public Property Firmware As String
Public Property Option1 As String
End Class
Public Class MainForm
Private Sub btnLoad_Click(sender As Object, e As EventArgs) Handles btnLoad.Click
Dim lines As String() = Nothing
Try
' Read the file in one step
lines = File.ReadAllLines("fwlist.txt")
Catch ex As Exception
Dim dialogResult As DialogResult = MessageBox.Show(Me, "File not found! Would you like to exit program?", "Error reading file", MessageBoxButtons.YesNo, MessageBoxIcon.Error, MessageBoxDefaultButton.Button2)
If dialogResult = DialogResult.Yes Then
Me.Close()
End If
Exit Sub
End Try
Dim firmwares As List(Of Firmware) = New List(Of Firmware)
For Each line As String In lines
Dim rawData As String() = line.Split({","}, StringSplitOptions.None)
' Create Firmware object from each line
Dim firmware As Firmware = New Firmware() With
{
.ModelName = rawData(0),
.PowerType = rawData(1),
.Pic = rawData(2),
.PartNumber = rawData(3),
.Firmware = rawData(4),
.Option1 = rawData(5)
}
' We store the read firmwares into a list
firmwares.Add(firmware)
Next
' Set the list as the data source of the combobox
' DisplayMember indicates which property will be shown in the combobox
With cboModelNames
.DataSource = firmwares
.DisplayMember = "ModelName"
End With
End Sub
Private Sub cboModelNames_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboModelNames.SelectedIndexChanged
RefreshForm()
End Sub
Private Sub RefreshForm()
' Get the selected item as Firmware object
Dim currentFirmware As Firmware = DirectCast(cboModelNames.SelectedItem, Firmware)
' Refresh all the textboxes with the information
With currentFirmware
txtPowerType.Text = .PowerType
txtPic.Text = .Pic
txtPartNumber.Text = .PartNumber
txtFirmware.Text = .Firmware
txtOption1.Text = .Option1
End With
End Sub
End Class
Every time you set the value of a variable like pwrtype, its old value is thrown away and there is no way to get it back. And even if you did save multiple values for each variable, you would need a way to figure out which value goes with the currently selected item in the combo box. To resolve these two issues you need:
a way to group values from the same line together
a way to save all values read from the file, not just the most recent ones
Let's start with the first issue, grouping values together. In the example code below, I created a Structure type called FirmwareInfo to serve that purpose. Each FirmwareInfo has its own pwrtype, pic, etc.
The other piece of the puzzle that you are missing is a way to save more than one Firmware. The easiest way to do this is to add each FirmwareInfo to the combo box's item list, instead of adding just the display string. The combo box will convert each item to a string in the UI; the ToString() method tells it how you want this conversion to be done.
I haven't run this example code so I can't guarantee there aren't mistakes in there, but hopefully it's enough to show the general idea.
Dim filename As String = "fwlist.txt"
Structure FirmwareInfo
Public pwrtype As String
Public pic As String
Public partnum As String
Public FirmwareName As String
Public Overrides Function ToString() As String
Return FirmwareName
End Function
End Structure
Private Sub ReadFirmwaresLoad(sender As Object, e As EventArgs) Handles Me.Load
' Load the items into the NameComboBox list.
Dim ResponseDialogResult As DialogResult
Try
Dim FirmwareStreamReader As StreamReader = New StreamReader(filename)
' Read all the elements into the list.
Do Until FirmwareStreamReader.Peek = -1
Dim lineread = FirmwareStreamReader.ReadLine()
Dim fields As String() = lineread.Split(",")
Dim info As New FirmwareInfo With {
.FirmwareName = fields(0),
.pwrtype = fields(1),
.pic = fields(2),
.partnum = fields(3)
}
cbFW.Items.Add(info)
Loop
' Close the file.
FirmwareStreamReader.Close()
Catch ex As Exception
' File missing.
ResponseDialogResult = MessageBox.Show("File not Found!", "File Not Found",
MessageBoxButtons.OK, MessageBoxIcon.Question)
If ResponseDialogResult = DialogResult.OK Then
' Exit the program.
Me.Close()
End If
End Try
End Sub
Private Sub cbFW_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cbFW.SelectedIndexChanged
Dim currentInfo = DirectCast(cbFW.SelectedItem, FirmwareInfo)
lblPwrType.Text = currentInfo.pwrtype
lblPic.Text = currentInfo.pic
lblPartNum.Text = currentInfo.parnum
' ....etc through options
End Sub
i have a textfile which is in this format
and i am trying to use a stream reader to help me loop each word into a text box, i am new to programming and really need help because all other examples are too complicated for me to understand,
this is what i am trying to do :
Dim objectreader As New StreamReader("filepath")
Dim linereader(1) As String
linereader = Split(objectreader.ReadLine, ",")
For i As Integer = 0 To UBound(linereader)
Spelling_Test.txtSpelling1.Text = linereader(0)
Spelling_Test.txtSpelling2.Text = linereader(0)
Next
but only get the first line of the text file in to a textbox, i need it to loop to the next line so i can write the next line in!
your help would be much appreciated, and if possible then can you show it practically , if you dont understand what i am trying to do then please ask
It is a little confusing on what you are trying to do, it looks like your text file consists of a word and a hint, you only have one set of textbox's and 3 lines of information in your file.
This example show you how to incrementally read your Stream.
Public Class Form1
Dim objectreader As StreamReader
Dim linereader() As String
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
If IsNothing(objectreader) Then
objectreader = New StreamReader("C:\Temp\data.txt")
End If
linereader = Split(objectreader.ReadLine, ",")
If String.IsNullOrEmpty(linereader(0)) Then
objectreader.Close()
objectreader = Nothing
Else
txtSpelling1.Text = linereader(0) 'Word
txtSpelling2.Text = linereader(1) 'Hint
End If
End Sub
End Class
But in your case, I would probably just use the File.ReadAllLines Method
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
Dim result As String() = File.ReadAllLines("C:\Temp\data.txt")
For x = 0 To UBound(result)
Dim c As Control = Controls.Find("txtSpelling" + (x + 1).ToString, True)(0)
If Not IsNothing(c) Then
c.Text = Split(result(x), ",")(0)
End If
Next
End Sub
So I feel like im pretty close, but I also have a feeling I am mixing up StreamReader and ReadAllLines
....................................................................................
Option Strict On
Imports System.IO
Public Class Form4
Dim file As System.IO.StreamWriter
Private Sub Form4_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
file = My.Computer.FileSystem.OpenTextFileWriter("c:\devices.bat", False)
file.WriteLine("#echo off")
file.WriteLine("cd " & Form1.TextBox2.Text)
file.WriteLine("adb devices > C:\devices.txt")
file.Close()
Shell("C:\devices.bat", AppWinStyle.Hide, True, 500)
Dim output() = System.IO.File.ReadAllLines("C:\deviceinfo2.txt")
Dim Devices As String = ""
Dim line() As String = {}
For X = 1 To output.Count = -1
line = output(X).Split(New Char() {(" ")})
Devices = line(0)
ComboBox1.Items.Add(Devices)
Next
output.Close()
output.Dispose()
End Sub
End Class
........................................................................
What I am trying to have it do is to start reading on line two of devices.txt and then read the first word from each line until the text file is done.
It seems simple enough, but like I said, I think I am mixing streamreader with readalllines
Any help is appreciated
Class Test
Public Sub Main()
Try
' Create an instance of StreamReader to read from a file.
' The using statement also closes the StreamReader.
Using sr As New StreamReader("TestFile.txt")
Dim line, firstWord As String
Dim i as Integer = 0
' Read and display lines from the file until the end of
' the file is reached.
Do
line = sr.ReadLine()
If Not (line Is Nothing) AndAlso i > 0 Then
firstWord = line.Split(" ")(i)
'do your logic
End If
i += 1
Loop Until line Is Nothing
End Using
Catch e As Exception
' Let the user know what went wrong.
End Try
End Sub
End Class
Grabbed this from MSDN and modified it. It should compile, but I didn't test it. This will loop through the lines, 1 by 1, skip the first line and grab each line's first word after. Hope this helps.