private void button1_Click(object sender, EventArgs e)
{
this.listBox1.Items[this.listBox1.SelectedIndex] = "this is item 5";
}
依照我的认知,不重新加载列表框是不可能实现的
button_onclick(object sender, EventArgs e)
{
this.listBox.SelectedItem.Text = "this is item 5";
}