Invalid operation in multiple threads

Question

I need two methods to be executing in parallel. Work() changes data inside infinite loop. Represent puts the changed data in the TextBox inside the infinite loop as well.

Log log = Log.GetInstance; //singleton
private void Work()
        {
            while (true) { //changing log }
        }   

private async void Represent()
        {
            await Task.Run(() =>
            {
                while (true)     
                {   
                    String str = String.Empty;
                    //generating str from log
                    textBox.Text = str;
                } 
            });
        }

private async void button_Click(object sender, EventArgs e)
        {
            await Task.Run(() => Work());
        }
public MainForm()
        {
            Represent();
        }

The problem is that textBox.Text = str; generates an error "invalid operation in multiple threads: attempt to access the control "textBox" from a thread in which it was created". How to solve that problem? Thanks in advance. P.S. Suggested method here for .NET 4.5 doesn't work because of the infinite loop.

Hopefully that error message is not literally what it says – harold May 06 '17 at 16:16 — harold, May 06 '17 at 16:16

score -1 · Answer 1 · edited May 23 '17 at 11:54

-1

Attempt to access member of System.Windows.Forms.Control from different thread than UI thread will cause cross-thread exception.

Take a look at the this: How to update the GUI from another thread in C#?

edited May 23 '17 at 11:54

Community

1
1

answered May 06 '17 at 16:13

ak92

41
9

score -1 · Accepted Answer · answered May 06 '17 at 16:16

for cross thread changing you need to invoking

use this code :

use this just for elements are in ui like textbox,combobox ,..... for public elements you don't need this

this.Invoke(new Action(() => { /*your code*/ }));

for your sample :

    Log log = Log.GetInstance; //singleton
private void Work()
        {
            while (true) { //changing log }
        }   

private async void Represent()
        {
            await Task.Run(() =>
            {
                while (true)     
                {   
                    String str = String.Empty;
                    //generating str from log
                   this.Invoke(new Action(() => { textBox.Text = str;}));
                } 
            });
        }

private async void button_Click(object sender, EventArgs e)
        {
            await Task.Run(() => Work());
        }
public MainForm()
        {
            Represent();
        }

Invalid operation in multiple threads

2 Answers2