Devexpress中Gridcontrol查找分组

private void button1_Click(object sender, EventArgs e)    {      DataTable dt = new DataTable();      dt.Columns.Add("Group");      dt.Columns.Add("idex");      dt.Columns.Add("name");      for (int i = 0; i < 5; i++)      {        DataRow dr = dt.NewRow();        dr["Group"] = "<5";        dr["idex"] = i.ToString();        dr["name"] = "姓名" + i.ToString();        dt.Rows.Add(dr);      }      for (int i = 5; i <= 10; i++)      {        DataRow dr = dt.NewRow();        dr["Group"] = "(5,10]";        dr["idex"] = i.ToString();        dr["name"] = "姓名" + i.ToString();        dt.Rows.Add(dr);      }      for (int i = 10; i <= 15; i++)      {        DataRow dr = dt.NewRow();        dr["Group"] = "(10,15]";        dr["idex"] = i.ToString();        dr["name"] = "姓名" + i.ToString();        dt.Rows.Add(dr);      }      gridColumnNumber.FieldName = "idex";      gridColumnName.FieldName = "name";      gridColumnGroup.FieldName = "Group";      gridColumnGroup.GroupIndex = 0;      gdc.DataSource = dt;      gdv.ExpandAllGroups();      for (int i = -1; gdv.IsGroupRow(i); i--)      {        DataRow dr = gdv.GetDataRow(gdv.GetDataRowHandleByGroupRowHandle(i));        if (dr == null) return;        if (dr["Group"].ToString() == "(5,10]")        {          gdv.CollapseAllGroups();          gdv.FocusedRowHandle = i;          gdv.SetRowExpanded(i, true);          return;        }      }    }