When selecting a certain value in the combobox, insert values in another

Question

I would like to enter values in combobox 2 depending on the choice in combobox 2.

I have this code but it does not work or insert the desired values in the combobox 2.

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (comboBox1.SelectedIndex = 1)
    {
        comboBox2.Items.Add(new Item("Blue", 1));
    }          
}

Answer 1

There is no way of knowing what mistake you are making. The question does not show enough details for this.

So I’m going to show you a minimal and complete working example.

In the Load of the Form I filled the first combobox and set the DisplayMember and ValueMember.

private void Form1_Load(object sender, EventArgs e)
{
    comboBox1.DataSource = new[]
    {
        new { Id = 1, Nome = "Item 0" },
        new { Id = 1, Nome = "Item 1" }
    }.ToArray();

    comboBox1.DisplayMember = comboBox2.DisplayMember = "Nome";
    comboBox1.ValueMember = comboBox2.ValueMember = "Id";
}

The SelectedIndexChanged is practically the same, I just corrected the syntax error you have in the question (are two signs of equal, not one) and I took that class Item because I don’t know how it was defined.

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (comboBox1.SelectedIndex == 1)
    {
        comboBox2.Items.Add(new { Id = 1, Nome = "Item 2" });
    }
}

See a working GIF

Answer 2

Apparently your code is correct, I believe it’s the problem in the if

if (comboBox1.SelectedIndex == 1)
{
    comboBox2.Items.Add(new Item("Blue", 1));
}  

Using to compare in if is ==.

And to add on the combobox, this is how:

comboBox1.Items.Add("Tokyo");  

Take a look at this link, change the way to add too.

Take the test, and report to me.