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Asynchronously Executing The Task Using Backgroundworker

In this article, we will discuss the BackgroundWorker class to run the task asynchronously.

Scenario

In this scenario, we will perform a task that takes time to execute and we make sure that the UI does not hang and still the task will execute in the background. For this article, we have the task of creating 10000 files with a button click.

The first step is to create a function. The purpose of the function is to create a file.

private void CreateFile(string filename) {
	FileInfo f = new FileInfo("d:\\File\\" + filename + ".txt");
	StreamWriter w = f.CreateText();
	w.WriteLine("This is the text");
	w.Close();
}

The second step is to create the object of the BackgroundWorker class.

private BackgroundWorker _BackgroundWorker;

The next step is to create a button. On the button click, add the following code: -

if (_BackgroundWorker == null) {
	_BackgroundWorker = new BackgroundWorker();
	_BackgroundWorker.DoWork += new DoWorkEventHandler(_BackgroundWorker_DoWork);
}

_BackgroundWorker.RunWorkerAsync();

In the above code, we are initializing the instance of the BackgroundWorker class and adding an event DoWork with it. The definition of the _BackgroundWorker_DoWork event is: -

void _BackgroundWorker_DoWork(object sender, DoWorkEventArgs e) {
	for (int i = 1; i < 10000; i++) {
		CreateFile(i.ToString());
	}
}

In the Do Work event, we will be executing the task. When RunWorkerAsync() is called, it will create a separate thread and start executing the task. Because the task is executed in a separate thread that is why the UI will remain responsive.

Passing Parameter Between Dowork And Runworkercompleted

To pass the parameter, we will assign the value to the Result property in the DoWork event. In the RunWorkerCompleted event, get the value using the Result property.

Example

Let us work on an example. In this example, we will perform the following actions: -

In the DoWork method, set the value of Result with the current date and time
Pause for 3 seconds using the sleep method
Display the current DateTime and DoWork datetime

Here is the code.

private void Form1_Load(object sender, EventArgs e) {
	BackgroundWorker _BackgroundWorker = new BackgroundWorker();

	_BackgroundWorker.DoWork += _BackgroundWorker_DoWork;
	_BackgroundWorker.RunWorkerCompleted += _BackgroundWorker_RunWorkerCompleted;
	_BackgroundWorker.RunWorkerAsync();
}

void _BackgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) {
	string timeString = string.Format("Current time: {0}{1} DoWork time:{2}", DateTime.Now.ToString(), Environment.NewLine, e.Result.ToString());
	MessageBox.Show(timeString);
}

void _BackgroundWorker_DoWork(object sender, DoWorkEventArgs e) {
	e.Result = DateTime.Now;
	System.Threading.Thread.Sleep(3000);
}

Output

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Saturday, January 8, 2011

Updated On -	Saturday, November 2, 2019

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