private void DisplayColumnNameLists()
{
InputColumnHeaders defaultColumnHeaders = geoCoder.DefaultInputColumnHeaders();
cboLevel1.DataSource = geoCoder.InputColumnHeaders();
//level 2 and 3 columns are optional so display a blank row at the top
IList <string> columnNames2 = geoCoder.InputColumnHeaders();
columnNames2.Insert(0, string.Empty);
cboLevel2.DataSource = columnNames2;
IList <string> columnNames3 = geoCoder.InputColumnHeaders();
columnNames3.Insert(0, string.Empty);
cboLevel3.DataSource = columnNames3;
// set defaults if they exist in the input sheet
cboLevel1.SelectedIndex = cboLevel1.FindStringExact(defaultColumnHeaders.Level1);
cboLevel2.SelectedIndex = cboLevel2.FindStringExact(defaultColumnHeaders.Level2);
cboLevel3.SelectedIndex = cboLevel3.FindStringExact(defaultColumnHeaders.Level3);
}