Windows forms data controls and databinding

Question

i'm trying to add list data object with list control two time.
1)first click on button when in list box there is no items [if block content]
2)second click onwards [else bock content]
problem is on second click data loading in list data object successfully but not displayed in list box.
public partial class Form11 : Form
List<string> str = new List<string>();
public Form11()
InitializeComponent();
private void button1_Click(object sender, EventArgs e)
if (listBox1.Items.Count == 0)
str.Add("A");
str.Add("B");
else
str.Add("C");
listBox1.DataSource = str;
            

Answer 1

Hi,
You need to clear the DataSource before reset it.
private void button1_Click(object sender, EventArgs e)
if (listBox1.Items.Count == 0)
str.Add("A");
str.Add("B");
else
str.Add("C");
listBox1.DataSource = null;// Reset the DataSource to null.
listBox1.DataSource = str;
If you have any other concern regarding this issue, please feel free to let me know.
Best regards,
Youjun Tang
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