C# Get textBox value from another class

Question

Let's say I have a form named Form1 with textBox and button in it.

I want to get the textBox value from another class on button click. I'm trying to do it like this, but it doesn't work:

class Main
{
    public void someMethod()
    {
        Form1 f1 = new Form1();
        string desiredValue = f1.textBox.Text;
    }
}

Forgive me for the dumb question, but I'm pretty new in C# and can't get this thing to work.

Answer 1

You need to find the opened Form1 instead of creating another Form1, create the following class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    class Class1
    {
        public void someMethod()
        {
            TextBox t = Application.OpenForms["Form1"].Controls["textBox1"] as TextBox;
            Debug.WriteLine(t.Text + "what?");
        }
    }
}

Then in your button click method

private void button1_Click(object sender, EventArgs e)
{
    Class1 c = new Class1();
    c.someMethod();
}