无缘无故地获得未发现的错误(Getting uncasted error for no reason)

无缘无故地获得未发现的错误(Getting uncasted error for no reason)

我对visual basic相当新，所以它可能很明显，但我认为没有理由抛出异常错误。 这是问题代码：

Public Sub textBoxFilePath_TextChanged(sender As Object, e As EventArgs) Handles textboxFilePath.TextChanged If textboxFilePath.Text.Trim.Length > 0 Then If My.Computer.FileSystem.FileExists(textboxFilePath.Text) Then Dim checkType As String checkType = System.IO.Path.GetExtension(textboxFilePath.Text) If checkType = ".xlsx" Or ".xls" Or ".xlsm" Then requiredPath = True Else requiredPath = False End If End If End If

我得到的错误是

Microsoft.VisualBasic.dll中发生未处理的“System.InvalidCastException”类型异常

附加信息：从字符串“.xls”到“布尔”类型的转换无效。

有任何想法吗？

I am fairly new to visual basic, so it may be obvious, but I see no reason for this to throw and uncasted exception error. Here is the problem code:

Public Sub textBoxFilePath_TextChanged(sender As Object, e As EventArgs) Handles textboxFilePath.TextChanged If textboxFilePath.Text.Trim.Length > 0 Then If My.Computer.FileSystem.FileExists(textboxFilePath.Text) Then Dim checkType As String checkType = System.IO.Path.GetExtension(textboxFilePath.Text) If checkType = ".xlsx" Or ".xls" Or ".xlsm" Then requiredPath = True Else requiredPath = False End If End If End If

The error I am getting is

An unhandled exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll

Additional information: Conversion from string ".xls" to type 'Boolean' is not valid.

Any ideas?

最满意答案

尝试这个：

If checkType = ".xlsx" Or checkType = ".xls" Or checkType = ".xlsm" Then requiredPath = True Else requiredPath = False End If

您的代码试图评估“.xls”（这是一个字符串），它不能很好地转换为布尔值true / false。

你也可以这样做来应用“短路”，所以只评估第一个是真的：

If checkType = ".xlsx" OrElse checkType = ".xls" OrElse checkType = ".xlsm" Then requiredPath = True Else requiredPath = False End If

Try this:

If checkType = ".xlsx" Or checkType = ".xls" Or checkType = ".xlsm" Then requiredPath = True Else requiredPath = False End If

Your code was trying to evaluate ".xls" (which is a string), which does not convert nicely to a boolean true/false.

You could also do this to apply "short circuiting", so only the first one true is evaluated:

If checkType = ".xlsx" OrElse checkType = ".xls" OrElse checkType = ".xlsm" Then requiredPath = True Else requiredPath = False End If