c# – 在组合框中设置默认项目

– 选项列表 –

public void SetoperationDropDown()

    {

        int? cbSelectedValue = null;
        if(cmbOperations.Items.Count == 0)
        {
            //This is for adding four operations with value in operation dropdown  
            cmbOperations.Items.Insert(0,"PrimaryKeyTables");
            cmbOperations.Items.Insert(1,"NonPrimaryKeyTables");
            cmbOperations.Items.Insert(2,"ForeignKeyTables");
            cmbOperations.Items.Insert(3,"NonForeignKeyTables");
            cmbOperations.Items.Insert(4,"UPPERCASEDTables");
            cmbOperations.Items.Insert(5,"lowercasedtables");
            //ByDefault the selected text in the cmbOperations will be -SELECT OPERATIONS-. 
            cmbOperations.Text = "-SELECT OPERATIONS-";
        }
        else
        {
            if(!string.IsNullOrEmpty("cmbOperations.SelectedValue"))
            {
                cbSelectedValue = Convert.ToInt32(cmbOperations.SelectedValue);
            }
        }
        //Load the combo Box cmbOperations again 
        if(cbSelectedValue != null)
        {
            cmbOperations.SelectedValue = cbSelectedValue.ToString();
        }
    }

有谁能建议这样做的方法？