DropdownList 赋初始值问题

网上查了这样的代码 虽然是可以用。但是会点击多次会出现”“ dropdownList不能选多个值的问题“

   private void initdroplistitemlirun(string c_Business)
        {
            if (this.Dplirun.Items.FindByText(c_Business) != null)
            {
                for (int i = ; i < this.Dplirun.Items.Count; i++)
                {
                    this.Dplirun.Items[i].Selected = false;
                    if (this.Dplirun.Items[i].Text == c_Business)
                    {
                        Dpcompany.SelectedIndex = -;
                        this.Dplirun.Items[i].Selected = true;
                        break;
                    }
                }
            }
        }
        private void initdroplistitem(string c_Business)
        {
            if (this.Dpchengben.Items.FindByText(c_Business) != null)
            {
                for (int i = ; i < this.Dpchengben.Items.Count; i++)
                {
                    this.Dpchengben.Items[i].Selected = false;
                    if (this.Dpchengben.Items[i].Text == c_Business)
                    {
                        Dpcompany.SelectedIndex = -;
                        this.Dpchengben.Items[i].Selected = true;
                        break;
                    }
                }
            }
        }

最后发现 其实 用一句话就可以 那就是

  this.Dpchengben.SelectedIndex = this.Dpchengben.Items.IndexOf(this.Dpchengben.Items.FindByText(YTmodel.goaltype.Trim()));