File is being used by another process with FileSystemWatcher and Task

Question

I have created an application that will watch a certain folder for only newly created files and list it in the listbox, now I want to do is everytime it will detect the file the application will read it and display the text on it in the listbox, I almost got because sometimes when it detects 2 or 3,4,5,6 etc files sometimes ok but sometimes also it will prompt error "The process cannot access the file 'C:\Users\PHWS13\Desktop\7.request.xml' because it is being used by another process.".

How to fix this? Here is my code:

private void fileSystemWatcher1_Created(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!listBox1.Items.Contains(e.FullPath))
        {
            //add path
            listBox1.Items.Add(e.FullPath + "" + DateTime.Now.ToString());
            //get the path
            path = e.FullPath;
            //start task
            startTask();
        }
    }

    private void startTask()
    {
        //start task
        Task t = Task.Factory.StartNew(runThis);
    }

    private void runThis()
    {
        //get the path
        string get_the_path = path;

        XDocument doc = XDocument.Load(get_the_path);
        var transac = from r in doc.Descendants("Transaction")
                      select new {
                          InvoiceNumber = r.Element("InvoiceNumber").Value,
                      };
        listBox2.Invoke((MethodInvoker)delegate() { 
            foreach(var r in transac){
                listBox2.Items.Add(r.ToString());
            }
        });

Answer 1

Try using XDocument.Load(Stream) with read-only options:

using (var stream = File.Open(filePath, FileMode.Open, FileAccess.Read)) 
{
    var doc = XDocument.Load(stream);

    // ...
}