CODEWITHSUNDEEP
c#winforms
cholewa1992
cholewa1992

Reputation: 893

Problems with Windows Forms

I have the following C# code:

using System;
using System.Windows.Forms;
namespace WinFormErrorExample 
{
    public partial class Form1 : Form
    {
        public static Form1 Instance;
        public Form1()
        {
            Instance = this;
            InitializeComponent();
        }

        public void ChangeLabel1Text(String msg)
        {
            if (InvokeRequired)
                Invoke(new Action<String>(m => label1.Text = m), new object[] {msg});
            else
                label1.Text = msg;
        } 

        static class Program
        {
            [STAThread]
            static void Main()
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
                Instance.ChangeLabel1Text("cool");
            }
        }
   }
}

When i'm calling the Instance.ChangeLabel1Text("cool"); nothing is happening in the GUI.

This is a small program i constructed to show my problem in a larger program.

Why is the GUI not being updated?

Upvotes: 0

Views: 422

Answers (3)

Sergey Vyacheslavovich Brunov
Sergey Vyacheslavovich Brunov

Reputation: 18096

The Application.Run(new Form1()); method call performs running a standard application message loop on the current thread. So, this line Instance.ChangeLabel1Text("cool"); will be executed when the application is closed.

Why not change the text of the label inside the constructor? No static variables needed.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        ChangeLabel1Text("Hello!");
    }
}

Upvotes: 0

Steve
Steve

Reputation: 216243

The call to 

Application.Run(new Form1());

is blocking your application until the Form1 closes. So your subsequent line is not executed until you try to close

Of course, if you just want to test the functionality of the Instance call then remove that line after the Application.Run. Instead you need to create a separate thread that tries to call that method on the Form1 current instance

Upvotes: 2

Kurubaran
Kurubaran

Reputation: 8902

This would do,

First set the text to textbox control and then Run()

Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Form1 form = new Form1();
form.Controls["ChangeLabel1Text"].Text = "cool";
Application.Run(form);

Upvotes: 0

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