如何以一种形式从另一种形式重新加载组合框项目

Question

I have two window forms, Form1 is for country name and Form2 is for city name. In form2 I have a comboBox which fetch country name from database that I saved by Form1 and its working fine and fetching data properly. But I want a button beside comboBox like please see this image for better understanding , and when click on it button will open Form1 and when I will add a new country in Form1, comboBox in Form2 should get updated and Form1 should close. How to do this? My code is...

In Form2 (for city name)

private void addBtn_Click(object sender, EventArgs e)
    {
        Add_Country ac = new Add_Country();
        ac.ShowDialog();
    }

public void refreshComboBox()
    {
        comboBox_CountryName.Refresh();
    }

In Form1(for country name)

private void saveBtn_Click(object sender, EventArgs e)
    {
        string country = txtBox_countryName.Text.ToLower();
        insertCountry(country);
        showCountry();
        Add_City ad = new Add_City(); //Form2 object refrence.
        ad.refreshComboBox();
        this.Close();
        MessageBox.Show("Country added successfully.");
        clearControl();
     }

Answer 1

The line ac.ShowDialog() helps you handle after the Add_Country form is closed. So, you can refetch the countries from database just after ShowDialog line such as;

private void addBtn_Click(object sender, EventArgs e)
{
    Add_Country ac = new Add_Country();
    ac.ShowDialog();
    // Repopulate the Country Combobox 
}

Answer 2

in form2 after showdialog() refresh your combo, you don't need to refresh it in the first form

private void addBtn_Click(object sender, EventArgs e)
{
    Add_Country ac = new Add_Country();
    ac.ShowDialog();
    refreshComboBox()
}

when you are closing the dialog the run time cursor will be back to the form2 and the other story will be executed