StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POCross-thread operation not valid: Control 'comboBoxLocation' accessed from a thread other than the thread it was created on
text
Body
copied!<p>I am new to threading and I am getting this error </p> <blockquote> <p>Cross-thread operation not valid: Control 'comboBoxLocation' accessed from a thread other than the thread it was created on.</p> </blockquote> <p>I dont know if I created this thread correctly but every time its given me that error. Does anyone know how to solve this issue. I already tried:</p> <pre><code>this.Invoke(new MethodInvoker(delegate() { da.SelectCommand.Parameters.AddWithValue("@QueueID", comboBoxLocation.SelectedValue.ToString()); })); </code></pre> <p>And I am still getting that error.</p> <pre><code>string branch; SpeechSynthesizer reader = new SpeechSynthesizer(); Thread t; bool flag; //SqlDataReader dr2; public Main() { InitializeComponent(); } private void btnStart_Click(object sender, EventArgs e) { lblStatus.Text = "Started!"; btnStop.Enabled = true; btnStart.Enabled = false; t = new Thread(Begin); //calls Begin method t.Name = "Queue"; //thread name t.Start(); //Starts thread flag = false; branch = comboBoxLocation.SelectedValue.ToString(); } private void btnStop_Click(object sender, EventArgs e) { lblStatus.Text = "Voice Application Termintated!"; btnStart.Enabled = true; btnStop.Enabled = false; t.Abort(); //Kills Thread flag = true; } //Began method public void Begin() { double announce; double announceID; string Stringannounce; string ticketNum, station, id, displaynum; string speak; try { using (SqlConnection connStr = new SqlConnection(ConfigurationManager.ConnectionStrings["AnnounceConnString"].ConnectionString)) { while (true) { //Selects Last record written to tblAnnounce SqlCommand sqlcommandStart = new SqlCommand("SELECT id, AnnounceID, AddDate FROM tblAnnounce ORDER by AddDate ASC", connStr); connStr.Open(); SqlDataReader dr = sqlcommandStart.ExecuteReader(); if (dr.HasRows) { while (dr.Read()) { Stringannounce = dr["AnnounceID"].ToString(); announceID = Convert.ToDouble(Stringannounce); SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 1 id, qdate, ticket_number, QueueID, received, displaynum, station, transcodevoiced FROM vwAnnounce WHERE QueueID = @QueueID ORDER by received ASC", connStr); //da.SelectCommand.CommandType = CommandType.StoredProcedure; DataSet ds = new DataSet(); *****************da.SelectCommand.Parameters.AddWithValue("@QueueID", comboBoxLocation.SelectedValue.ToString());***** //ERROR HERE da.Fill(ds); DataTable dt = new DataTable(); dt = ds.Tables[0]; foreach (DataRow dr2 in dt.Rows) { id = dr2["id"].ToString(); announce = Convert.ToDouble(id); ticketNum = dr2["ticket_number"].ToString(); station = dr2["station"].ToString(); //transcodevoiced = dr2["transcodevoiced"].ToString(); displaynum = dr2["displaynum"].ToString(); SplitString splitter = new SplitString(displaynum); splitter.Split(); if (announceID == announce) { // Set a value for the speaking rate. reader.Rate = -4; // Set the volume of the SpeechSynthesizer's ouput. reader.Volume = 85; //String that will be spoken speak = "Now, " + displaynum + ", at #" + station; //The problem with the Speak() function is that it is not threaded, so we use SpeakAsync(). It means that you cannot perform any other function in your windows form until the "reader" object has completed the speech. reader.SpeakAsync(speak); //Pauses system for 1 seconds after voice completion Thread.Sleep(3000); //Deletes record from Database table tblAnnounce SqlCommand delete = new SqlCommand("DELETE FROM tblAnnounce WHERE AnnounceID = @announceID ", connStr); delete.Parameters.AddWithValue("@announceID", announceID); delete.ExecuteNonQuery(); reader.Resume(); } } } connStr.Close(); } dr.Close(); } } } catch(Exception ex) { string exception = ex.Message; } } </code></pre>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload