Question

Edit: I solved the problem by creating the background worker by creating it in code instead of dragging and dropping in design.

Now I know how to use a background worker.

Question

It’s my first time using a BGWorker, so here’s my issue…

• The cursor doesn’t change to “Wait”.
• The progress bar doesn’t update.
• RunWorkerCompleted isn’t invoked.

But the textbox does update.

Am I doing something wrong ?

The Code

using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace BGWorker
{
    public partial class Main : Form
    {
        public Main()
        {
            InitializeComponent();
            progressBar1.Minimum = 0;
            progressBar1.Value = 0;
            progressBar1.Maximum = 100;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Cursor.Current = Cursors.WaitCursor;
            backgroundWorker1.RunWorkerAsync();
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 1; i <= 100; i++)
            {
                textBox1.AppendText(i.ToString());
                textBox1.AppendText("\n");
                backgroundWorker1.ReportProgress(i);
            }
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                label1.Text = e.Error.Message;
            }

            else
            {
                label1.Text = "All Done !";
                Cursor.Current = Cursors.Default;
            }

        }
    }
}

Thanks.

Answer 1

I agree with pst.

1. Always create your worker in the code behind – dragging and dropping on the form is never a good idea
2. You never access UI elements from the DoWork. You can only do this from the ReportProgress and RunWorker Completed Events

3. Your if statement segment should contain your most common path with the least common path in the else.

   private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
   {
       StringBuilder sb = new StringBuilder();
       for (int i = 1; i <= 100; i++)
       {
           sb.AppendLine(i.ToString());
           backgroundWorker1.ReportProgress(i);
       }
       e.Result = sb.ToString();
   }
   
   private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
   {
       if (e.Error == null)
       {
           textbox1.Text = e.Result.ToString();
           label1.Text = "All Done !";
           Cursor.Current = Cursors.Default;
       }
   
       else
       {
           label1.Text = e.Error.Message;
       }
   }