C＃列表框selectedItem不起作用

Question

Ok, I would like somebody to try this and give me a specific working answer. I have a ListBox control that has items and I have an event handler for ListBox.SelectedIndexChanged.

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    updateTextBox2(); //sets the selectedIndexItem to textbox2
}

In another function I have this code:

listBox1.SelectedIndex = (listBox1.SelectedIndex + 1) % listBox1.Items.Count;

It does move to the next item but it doesn't raise the event.

I have also tried this without raising an event

listBox1.SelectedIndex = (listBox1.SelectedIndex + 1) % listBox1.Items.Count;
updateTextBox2(); //

but the listbox item is still not copied into the textbox until I actual click on the listbox

Answer 1

Try this

    private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        updateTextBox1(); 
    }

    private void updateTextBox1()
    {
        textBox1.Text = Convert.ToString(listBox1.SelectedIndex);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        listBox1.SelectedIndex = (listBox1.SelectedIndex + 1) % listBox1.Items.Count;
        listBox1_SelectedIndexChanged(sender, e);
    }

if you are wanting to raise the event though another method, you need to use

listBox1_SelectedIndexChanged(sender, e);

the event is only raised automaticaly when you invoke it. Also you could just invoke the update method, id need to see more code to understand why it wouldn't work.

private void button1_Click(object sender, EventArgs e)
    {
        listBox1.SelectedIndex = (listBox1.SelectedIndex + 1) % listBox1.Items.Count;
        updateTextBox1();
    }

Answer 2

I don't know if it works for ListBox, but I know it does for ListView so it's worth a shot. Try setting the selection like this instead:

listBox1.Items[listBox1.SelectedIndex].Selected = false; // Not 100% sure the Items have a Selected property
listBox1.Items[(listBox1.SelectedIndex + 1) % listBox1.Items.Count].Selected = true;

That might fire the event.