如何更改 WPF 中 Textblock 的文本属性？

Question

I have a Form in WPF and a DispatcherTimer, every time the tick event fires I want to change the value of OrderLbl.Text from "Today's orders" to "this week's orders", and from "this week's orders to "This Month's Orders".

However, when I attempt to change the value of OrderLbl.text from the _timer_Tick event, it throws an exception saying an object reference is required, however when I reference this inside the tick event it will not change the value of OrderLbl.Text

Code is below;

 public void Start()
    {

        System.Windows.Threading.DispatcherTimer DTimer = new System.Windows.Threading.DispatcherTimer();
        DTimer.Tick += new EventHandler(_timer_Tick);
        DTimer.Interval = new TimeSpan(0, 0, 5);
        DTimer.Start();


    }

    private static void _timer_Tick(Object sender, EventArgs e)
    {

         if (OrderLbl.Text == "Today's Orders")
        {
            OrderLbl.Text = "This Week's Orders";

        }


        else if (OrderLbl.Text == "This Week's Orders")
        {
           OrderLbl.Text = "This Month's Orders";

        }

        //else
        //{
        //    mw.orderlbl.text= "today's orders";
        //    go
        //}

    }

Answer 1

Remove the static keyword from the Tick handler:

private void _timer_Tick(Object sender, EventArgs e)
{
    ...
}