Update label text in background worker winforms

问题

I am using BackGroundWorker class to insert some values in sqlserver. I have for loop here to insert values. i am using following code

 public void bw_Convert_DoWork(object sender, DoWorkEventArgs e)
    {           
        e.Result = e.Argument;
        for (int i = 0; i <  fTable.Rows.Count; i++)
        {
            try
            {
                SqlCommand cmd = new SqlCommand("INSERT INTO TBL_CDR_ANALYZER (LNG_UPLOAD_ID, DAT_START, LNG_DURATION, INT_DIRECTION, INT_CALL_DATA_TYPE, \n" +
                    "TXT_TARGET_NUMBER, TXT_OTHER_PARTY_NUMBER, TXT_TARGET_IMSI, TXT_TARGET_IMEI, TXT_TARGET_CELL_ID, TXT_ROAMING_NETWORK_COMPANY_NAME) VALUES \n" +
                    "(@UPLOAD_ID, @START_DATE, @DURATION, @DIRECTION, @CALL_TYPE, @TARGET_NUMBER, @OTHER_PARTY_NUMBER, @IMSI, @IMEI, @CELL_ID, @ROAMING_NAME)", sqlCon);
                cmd.Parameters.Add("@UPLOAD_ID", SqlDbType.Int).Value = 1;
                cmd.Parameters.Add("@START_DATE", SqlDbType.DateTime).Value = fTable.Rows[i]["CallDate"];
                cmd.Parameters.Add("@DURATION", SqlDbType.Int).Value = fTable.Rows[i]["CallDuration"];
                cmd.Parameters.Add("@DIRECTION", SqlDbType.Int).Value = GetCallDirection(fTable.Rows[i]["CallDirection"].ToString());
                cmd.Parameters.Add("@CALL_TYPE", SqlDbType.Int).Value = GetCallType(fTable.Rows[i]["CallType"].ToString());
                cmd.Parameters.Add("@TARGET_NUMBER", SqlDbType.VarChar, 25).Value = fTable.Rows[i]["TargetNo"];
                cmd.Parameters.Add("@OTHER_PARTY_NUMBER", SqlDbType.VarChar, 25).Value = fTable.Rows[i]["OtherPartyNo"];
                cmd.Parameters.Add("@IMSI", SqlDbType.VarChar, 50).Value = fTable.Rows[i]["IMSI"];
                cmd.Parameters.Add("@IMEI", SqlDbType.VarChar, 50).Value = fTable.Rows[i]["IMEI"];
                cmd.Parameters.Add("@CELL_ID", SqlDbType.VarChar, 50).Value = fTable.Rows[i]["CellID"];
                cmd.Parameters.Add("@ROAMING_NAME", SqlDbType.NVarChar, 255).Value = fTable.Rows[i]["RoamingCompany"];
                sqlCon.Open();
                cmd.ExecuteNonQuery();
                sqlCon.Close();
            }
            catch (SqlException ex)
            {

            }
            finally
            {
                sqlCon.Close();
            }
            bw_Convert.ReportProgress((100 * i) / fTable.Rows.Count);  
            **Label1.Text = i.ToString() + "Files Converted";** // getting error Here.                  
        }    
    }

How can i update the Label1 text here

回答1:

This should work to change the GUI from a background thread.

Label1.Invoke((MethodInvoker)delegate {
   Label1.Text = i.ToString() + "Files Converted";});

回答2:

You can't access UI interface objects like a label inside a DoWork method.
The DoWork is running on a different thread than the UI elements.
You need to update your interface through the ProgressChanged event or calling a delegate.

First set the WorkerReportsProgress property of the BackgroundWorker to True, then, the call to ReportProgress method, will raise the event ProgressChanged that will be run in the same thread of your interface elements

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
     Label1.Text = e.ProgressPercentage.ToString();
}

回答3:

You have to implement the ProgressChanged-Event.

private void bw_Convert_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
   //The progress in percentage
   int progress = e.ProgressPercentage;
   //A custom-value you can pass by calling ReportProgress in DoWork
   object obj = e.UserState;
}

回答4:

//You can also try this update your label

this.Invoke(new MethodInvoker(delegate 
          {
             Label1.Text = i.ToString() + "Files Converted";
          }));

回答5:

I was having the same issue. I was already within the Progress Changed Background Worker Event but even using both versions of the Method Invoker above did not help. Then I tried this and it worked:

 lblCount.Text = string.Format("Total Directories: {0} Total Files: {1}", TotalDirectories, TotalFiles);
 lblCount.Update();

来源：https://stackoverflow.com/questions/15759688/update-label-text-in-background-worker-winforms

标签

winforms

backgroundworker