How to send parameters together with a method to a new thread?

Question

At the moment, I've got working:

public void logowanie()
{
int x=5,y=5;
...
}

private void button2_Click(object sender, EventArgs e)
        {
            Thread thread2 = new Thread(new ThreadStart(logowanie));
            thread2.Start();
            //logowanie("xd", "xd", "xd");

        }

And that works. Is it possible to make something like

public int logowanie(int x, int y)
{
...
}

private void button2_Click(object sender, EventArgs e)
        {
            Thread thread2 = new Thread(new ThreadStart(logowanie(5,5)));
            thread2.Start();
            //logowanie("xd", "xd", "xd");

        }

I've just started with threading things. Thanks

Answer 1

While you could use ParameterizedThreadStart , I'd probably just use a lambda expression:

private void button2_Click(object sender, EventArgs e)
{
    Thread thread2 = new Thread(() => logowanie(5, 5));
    thread2.Start();
}

Note that if you call this in a loop, you'll need to be careful because of the way that variables are captured by lambda expressions:

// Broken (before C# 5)
foreach (string url in urls)
{
    new Thread(() => CrawlUrl(url));
}

// Fixed
foreach (string url in urls)
{
    string copy = url;
    new Thread(() => CrawlUrl(copy));
}

This is only an issue in certain situations where you're capturing a variable and really want to capture the current value instead, but it's worth knowing about.

Answer 2

You can use ParameterizedThreadStart and pass an object to the thread:

class ParametersForThread
{
    public int x;
    public int y;
}

...

Thread thread2 = new Thread(new ParameterizedThreadStart(logowanie));
thread2.Start(new ParametersForThread() { x = 5, y = 5 });

Your thread method must look like

void logowanie(object state)
{
    ParametersForThread parameters = state as ParametersForThread;
    ....;
}

Answer 3

Create a new class or struct. Pass that and cast it.

Answer 4

Use a delegate. You can either define your own or use one of the built-in general purpose ones like Action, Action(T) or, in your case Action(T1,T2)

private Action<int,int> myLoggingDelegate;


private void button2_Click(object sender, EventArgs e)
{
    myLoggingDelegate = logowanie;
    myLoggingDelegate.BeginInvoke(myParam1,myParam2,Callback,null);    //this is aynchronous
}

private void Callback(IAsyncResult ar)
{
    myLoggingDelegate.EndInvoke(ar);
}

Answer 5

Or you can use inline code, the parameters will be automatically passed to the new thread.

void method()
{
    int a = 5, b = 6;
    Thread t  = new Thread(delegate()
    {
        CallOtherMethodOnTheNewThread(a, b);
    });
    t.Start();
}

Answer 6

Step 1: create a class to combine parameters on a single object:

private class ThreadParams {
  public int X { get; set; }
  public int Y { get; set; }
  public ThreadParams(int x, int y)
  {
    this.X = x;
    this.Y = y;
  }
}

Step 2: declare this object on your method:

public void logowanie(ThreadParams param)
{
...
}

Step 3: send the values with ParameterizedThreadStart:

Thread thread = new Thread(new ParameterizedThreadStart(logowanie));
ThreadParams prm = new ThreadParams(5,5);
thread.Start(prm);