检查字符串值如果在VB.net有效日期

Question

我的问题是当我收到一个字符串，并且不是日期格式。并把错误置于文本框中。

例子：

Public Sub get_error(ByVal sheet_name As String, ByVal column_name As String, ByVal row_count As String, ByVal row_value As String) 
     Dim dt_row_service_provider_code As String = row_value 
     If dt_row_service_provider_code Is Nothing Or dt_row_service_provider_code = "" Then 
      dt_row_service_provider_code = "Empty Value" 
     End If 
     If dt_row_service_provider_code.Length > 50 Then 
      dt_row_service_provider_code = "Characters is greater than 50" 
     End If 
     txtError.Text += "sheet: " & sheet_name & " | column: " & column_name & " | row: " & (row_count + 2) & " | row value is: '" & dt_row_service_provider_code & "'" & Environment.NewLine 
    End Sub 

    'dr(2).Tostring contains word "test" 
    For Each dr As DataRow In dt.Rows 
     Dim holiday_code As String = dr(0).ToString 
     Dim holiday_desc As String = dr(1).ToString 
     Dim holiday_date As String = dr(2).ToString 
     If holiday_date Is Nothing Or holiday_date = "" Then 
      get_error(dt.TableName, dt.Columns(2).ToString, dt_row.ToString, "Empty Value") 
     End If 

      If isDate(holiday_date) = False Then 
      'show error message in textbox 
      get_error(dt.TableName, dt.Columns(2).ToString, dt_row.ToString, "Value is not a valid Date") 
      End If 
     Next 

这是我的只是例子，因为我的计划是进口擅长数据库，我只是把一些情况下，如果用户一不小心就会在Excel中添加日期格式的字。现在我怎么能把错误放在文本框？我不想只显示一个例外，但我想把错误置于文本框中

Answer 1

更新了我的答案。

Public Sub get_error(ByVal sheet_name As String, ByVal column_name As String, ByVal row_count As Integer, ByVal row_value As String) 
    Dim dt_row_service_provider_code As String = row_value 
    txtError.Text += "sheet: " & sheet_name & " | column: " & column_name & " | row: " & (row_count + 2) & " | row value is: '" & dt_row_service_provider_code & "'" & Environment.NewLine 

End Sub 

For Each dr As DataRow In dt.Rows 
    Dim holiday_code As String = dr(0).ToString 
    Dim holiday_desc As String = dr(1).ToString 
    Dim holiday_date As String = dr(2).ToString 
    Dim newDate As DateTime 
    Try 
     newDate = DateTime.Parse(holiday_date) 
    Catch ex As Exception 
     If holiday_date = "" Or holiday_date Is Nothing Then 
      get_error(dt.TableName, dt.Columns(2).ToString, dt.Rows.IndexOf(dr), "Empty Value") 
     Else 
      get_error(dt.TableName, dt.Columns(2).ToString, dt.Rows.IndexOf(dr), "Value is not a valid Date") 
     End If 
    End Try 
Next