C＃Winforms ListBox项目

Question

I have sevral text entries in a listbox , we'll call it ListBox1 .

Ive been searching google, social.msdn.microsoft.com, and here. I cant figure out how to have each text entry change something when selected.

ie

string1 causes ((value1 + value2) / 2)

string2 cuases ((value3 + value4) / 2)

string3 causes ((value5 + value6) / 2)

Im obviously new.

Answer 1

You need to handle the ListBox.SelectedValueChanged event.

In main, or by using the designer, register the event handler:

listBox1.SelectedValueChanged += listBox1_SelectedValueChanged;

Then, your event handler:

void listBox1_SelectedValueChanged(object sender, EventArgs e) {
    string value = listBox1.SelectedValue as string;
    if (value == null) return;

    // What to do now?
    switch(value) {
        case "string1":
            // Do something...
            break;

        case "string2":
            // Do something...
            break;

        case "string3":
            // Do something...
            break;
    }
}

Answer 2

You can use the SelectedIndexChanged event to execute code when items are selected. You can either test SelectedIndex or SelectedItem to see which item has been selected.

    private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (listBox1.SelectedItems.Count == 0)
            return;

        int selectedItemIndex = listBox1.SelectedIndex;
        string selectedItemText = listBox1.SelectedItem.ToString();

        // E.g.
        this.Text = selectedItemText;
    }