Using a method to manipulate a control in WinForms

I us开发者_开发百科e the same code to fill a control in my WinForms over and over again, so I figured: Hey, you should make it a method instead of copy-pasting it!

So, I created this in my Main class

Main

internal static void FillWithStuff(RichTextBox box)
{
 Data data = GetSomeData("doesn't matter");
 foreach (Row row in data)
 {
  box.Text += row.ToString() + "\r\n";
 }
}

WinForm

internal RichTextBox textBox = new RichTextBox();
// Some code
Main.FillWithStuff(textBox);

So, the method executes without exceptions or warnings, but the data is not filled in the box. I checked if the data was loaded and it is, so the problem has to be somewhere else.

How should I implement this correctly?

---

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private List<string> GetStuff()
        {
            List<string> stuff = new List<string>();

            stuff.Add("foo");
            stuff.Add("bar");
            stuff.Add("baz");

            return stuff;
        }

        private void FillWithStuff(TextBoxBase textBox)
        {
            List<string> stuff = GetStuff();

            foreach (string s in stuff)
            {
                textBox.Text += s + "\r\n";
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            FillWithStuff(richTextBox1);
        }
    }
}

That works as you would expect. Comparing it with what you have makes me think you have a problem somewhere else. Are you sure row.ToString() is returning a non-empty string?

---

Did you Call Main.FillWithStuff(...) after something like Application.Run(form) or form.ShowDialog()? In that case, Main.FillWithStuff(..) will not execute unless you close the form, try to move your method call before it

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Can you paste in the entire code for the Winform?

From what I can tell it's a form-level variable as it's marked internal.

I tested this using a form that was already on the form as well as one that's dynamically created and both times it filled the RichTextBox with the text as expected.

Try putting a break point in your foreach loop and ensure it's returning data.