C# WPF 控制表格form2

Question

I created the project for C# WPF (.NET Core 3.1). I added one button and one richtextbox. I created a new Bypass class file in the project. I write code to Bypass class like access from form1 to form2.

BypassClass file code:

   public void Start()
    {
        MainWindow Form1 = new MainWindow();
        RichTextBox LogBox = Form1.LogBox;

        LogBox.AppendText("Hello \rf");

    }

button code:

Bypass BypassClass = new Bypass();
BypassClass.Start();

I have tried this code. Button1 I clicked the button. RichTextBox 'Hello' did not come. VB.NET encoding works using:

MyProject.Forms.Form1.Richtextbox1.AppendText("Hello");

enter image description here

I want coding like this picture. Waiting for help Thanks for reviewing the subject.

Answer 1

You are creating a new instance of MainWindow in your Start() method. What you want to do is to get a reference to the window that is currently displayed on the screen:

public void Start()
{
    MainWindow Form1 = Application.Current.Windows.OfType<MainWindow>().FirstOrDefault();
    if (Form1 != null)
    {
        RichTextBox LogBox = Form1.LogBox;
        LogBox.AppendText("Hello \rf");
    }
}