Re: Creating a new thread
very nice & easy... thx for the tip
i have 1 question though ....
how do i re-run the thread ?
for eg. i have inserted execution of a batch file under the thread using :
Code:
Private Sub threadfunc()
While running
Shell("c:\mymusic\list.bat", AppWinStyle.Hide, True)
running = False
End While
End Sub
batch file takes abt few seconds to run & then i dump batch file's output into a text box on my form, it works fine for the first time but then when i try to run it for the second time it says :
"Thread is running or terminated; it cannot restart."
here's my full code if it helps, it simply lists the contents of directory & dumps it in a textbox, i know i can do this w/o a batch file, but i just wanted to test the "threading" stuff, & i knw it's a crappy one coz i'm just a beginner in vb .net ;-)
Code:
Imports System.IO
Public Class Form1
Dim t = New Threading.Thread(New Threading.ThreadStart(AddressOf threadfunc))
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fiFile As New System.IO.FileInfo("c:\mymusic\list.bat")
fiFile.Delete()
Dim objStreamWriter As StreamWriter
objStreamWriter = New StreamWriter("c:\mymusic\list.bat", True)
objStreamWriter.WriteLine("c:")
objStreamWriter.WriteLine("cd\")
'objStreamWriter.WriteLine("cd windows")
objStreamWriter.WriteLine("dir /s > c:\mymusic\list.txt")
objStreamWriter.Close()
t.start()
PictureBox1.Visible = True
Me.Refresh()
TWAIT:
If running = False Then
Dim myOutput = New StreamReader("c:\mymusic\list.txt")
Dim sValues = myOutput.ReadToEnd
Me.rtb1.Text = sValues
Else
PictureBox1.Visible = True
Me.Refresh()
GoTo TWAIT
End If
PictureBox1.Visible = False
running = False
End Sub
Private running As Boolean = True
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
PictureBox1.Visible = False
End Sub
Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
running = False
t.Abort()
End Sub
Private Sub threadfunc()
While running
Shell("c:\mymusic\list.bat", AppWinStyle.Hide, True)
running = False
End While
End Sub
End Class
picturebox? = i have inserted a animated gif that is displayed till the batch file is running in back ground
Re: Creating a new thread
To re-run the thread, you need to create a new thread and start that. So instead of only creating a new instance of the thread object at class level, create a new instance in your button click event handler. Also, I would suggest that if you want the thread to end when your application ends, you dont need to call Thread.Abort in the form closing event, you can just set the thread's IsBackground property to True and it will automatically close when the application ends (unless of course this is not your main form and you just want the thread to end when this form is closed).
So here is an example of the relevant parts of your code but adapted with both of the above suggestions:
Code:
Public Class Form1
Dim t As Threading.Thread
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fiFile As New System.IO.FileInfo("c:\mymusic\list.bat")
fiFile.Delete()
Dim objStreamWriter As StreamWriter
objStreamWriter = New StreamWriter("c:\mymusic\list.bat", True)
objStreamWriter.WriteLine("c:")
objStreamWriter.WriteLine("cd\")
'objStreamWriter.WriteLine("cd windows")
objStreamWriter.WriteLine("dir /s > c:\mymusic\list.txt")
objStreamWriter.Close()
t = New Threading.Thread(New Threading.ThreadStart(AddressOf threadfunc))
t.IsBackground = True
t.start()
Re: Creating a new thread
for some reason, doesn't work :( the problem occurs when i run it for the second time , it simply does not execute the batch file [under "shell"]
can i do this using background worker ?:confused:
Re: Creating a new thread
Quote:
Originally Posted by
sk8er_boi
for some reason, doesn't work :( the problem occurs when i run it for the second time , it simply does not execute the batch file [under "shell"]
can i do this using background worker ?:confused:
hey ...GOT IT !
it wasn't the thread, it was problem with my code, i didn't close the StreamReader due to which batch file cudn't write the output , works fine now
thx all for help ! :check:
Re: Creating a new thread
You don't have to abort the thread, which is not good if you can avoid it.
Just call t.Join() after setting the flag to False. Or possibly:
Code:
If Not t.Join(1000) Then t.Abort()
. Or you can abort it without setting the flag.
Re: Creating a new thread
Is that better? I changed it in the code above.
vb Code:
If t.IsAlive = True Then
t.Abort()
End If
Re: Creating a new thread
Again, you're testing a Boolean value against true ^^. And that wasn't what I said, either. Just put that code exactly where you have all that thread-aborting code.
Re: Creating a new thread
To sum up:
Code:
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
t = New Threading.Thread(New Threading.ThreadStart(AddressOf threadfunc))
t.IsBackground = True
t.Start()
End Sub
Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
running = False
If t.IsAlive AndAlso (Not t.Join(1000)) Then t.Abort()
End Sub
Private Sub threadfunc()
While running
'PUT YOUR CODE HERE
End While
End Sub
