calling method on one form from another form, fill combobox on Form1 if a button on Form2 is clicked

Question

I want to fill a combobox on Form1 , when the OK button on Form2 is clicked.

First, the Load Form2 button on Form1 is clicked to display Form2. Then, Form2 appears, and

Answer 1

Updated

You can try passing Form1 instance in the constructor of Form2

Example:

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

    private void button1_Click(object sender, EventArgs e)
    {
        Form2 form2 = new Form2(this);
        form2.Show();
    }

    internal void TestMethod()
    {
        throw new NotImplementedException();
    }
}

public partial class Form2 : Form
{
    private Form1 form1;

    public Form2()
    {
        InitializeComponent();
    }

    public Form2(Form1 form1)
        : this()
    {
        // TODO: Complete member initialization
        this.form1 = form1;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        form1.TestMethod();
    }
}

Updated

try this:

public  FORM2(SqlConnection connfromFORM3, FORM1 form1)
{
    this.form1 = form1;
    Form2Conn = connfromFORM3;
    InitializeComponent();
}