How to remove 'System.InvalidOperationException'?

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2.25/5 (4 votes)

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when I am running my code following error appeard which then showed that it linked to the update of a textBox in each iteration.

C#

epoch++;
// check the conditions to stop
if ((epochs != 0) && (epoch > epochs))
    break;

// set current epoch's info
textBox.Text = epoch.ToString();

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

The calling thread cannot access this object because a different thread owns it.

How can I resolve it?

regards
AM

Posted 8-Jul-15 4:24am

ARMS_DEIR

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Herman<T>.Instance · Accepted Answer · 2015-07-08T04:36:00

Solution 1

easy, you are using more threads. But the GUI thread cannot be updated from another thread. You need some invoking:

C#

textBox.Invoke(new Action(()=> textBox.Text = epoch.ToString()));

That should do the trick!
All you GUI components need INVOKE when updating the values from a different thread.

GOOD Luck.

Posted 8-Jul-15 4:36am

Herman<T>.Instance

Comments

Sergey Alexandrovich Kryukov 15-Jul-15 11:35am

5ed.
—SA

Herman<T>.Instance 16-Jul-15 3:44am

thanx

ARMS_DEIR 20-Jul-15 8:07am

How to avoid it from a combobox? I tried the same command but it didn't work:

Could you also please explain what does this THREAD do to avoid it later or inst it possible?

Herman<T>.Instance 20-Jul-15 8:13am

Do you want to read or want to set the value of a combobox item?

Threads. that's quite a story.
When you have an application you have a gui thread which runs continuous. When you set a variable in a property of you object (like Text from a TextBox) you do that in the same thread. When you have a lot of processing to do before you can display anything you see a freezing windows from. To prevent that it is possible to have the processing work done by another thread. In that case you have no freeze. The problem however is that the result of the processing is in the other thread and has to be handed over to the GUI thread. In that case the Invoke method must be used to have the result available to display in your GUI.

ARMS_DEIR 20-Jul-15 8:35am

I want to use the selected index of the defined combobox.

Is the number of Threads fixed or can I have as many as I want?

Herman<T>.Instance 20-Jul-15 8:53am

what do you invoke? the comboBox.Invoke() or this.Invoke()
Max numbers of threads is 100 per core if I am correct

Herman<T>.Instance 20-Jul-15 8:14am

Hint: see here