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我一直在尋找我的問題的答案，我一直沒能找到太多，所以我在這裏發佈，希望更有經驗的開發人員能夠啓發我。在子結構中構造異常處理的正確方法是什麼？我是否應該包裝我的Try，Catch，End嘗試圍繞我的整個代碼塊，或者可以包裝Try，Catch，End嘗試圍繞我的子塊中的一個塊，然後嘗試，捕獲，結束嘗試圍繞另一塊代碼在同一個子？下面是我要問一個例子：在VB.NET中適當的異常處理
這是更好的？：（OPTION 1）
Try
'check if user has selected a file
If ListBoxPrePublish.SelectedItems.Count = 0 Then
MessageBox.Show("Please select a file to delete.")
Exit Sub
End If
'check if user has selected a Memo to publish, if so, move file to Publish folder; if user hasn't selected a Memo, move to next If statement
If ListBoxPrePublish.SelectedItem.Contains("-M.xls") Then
Dim resultMemo = MessageBox.Show("Are you sure you want to delete this Memo?", "", MessageBoxButtons.YesNo)
If resultMemo = DialogResult.Yes Then
Dim filePath As String = "W:\TOM\ERIC\Award_Letters\Excel pre_publish\"
Dim movePath As String = "W:\TOM\ERIC\Award_Letters\Publish\"
Dim filenm As String = ListBoxPrePublish.SelectedItem
Dim FileToMove = filePath & filenm
Dim MoveToLocation = movePath & filenm
'move the file
System.IO.File.Move(FileToMove, MoveToLocation)
ListBoxPublished.Items.Add(ListBoxPrePublish.SelectedItem)
ListBoxPrePublish.Items.Remove(ListBoxPrePublish.SelectedItem)
Exit Sub
Else
Exit Sub
End If
End If
'ask user if they're sure they want to publish selected file and corresponding files...remember, only if the selected item is not a Memo
Dim result = MessageBox.Show("This action will publish all corresponding files for the selected student except for Memos. Memos must be deleted individually. Do you want to continue?", "", MessageBoxButtons.YesNo)
If result = DialogResult.No Then
Exit Sub
Else
If result = DialogResult.Yes Then
'find ID for student in unapprovd accounting file, move the record to the Deleted Today file, delete record from unapproved accounting file
Dim UnapprovedAcctFile As String = "W:\TOM\ERIC\Award_Letters\Accounting Files\Unapproved\" & StatVar.xlApp.Sheets("New Calculator Input").Range("D30").Value & ".xlsx"
Dim ApprovedAcctFile As String = "W:\TOM\ERIC\Award_Letters\Accounting Files\Approved\" & StatVar.xlApp.Sheets("New Calculator Input").Range("D30").Value & " Import" & ".xlsx"
Dim searchString As String = StatVar.xlApp.Sheets("Cross Checking").Range("J6").Text 'this is the ID that will be searched for in the accounting file
Dim rng
'make sure accounting file for school exists
If Not IO.File.Exists(UnapprovedAcctFile) Then
MessageBox.Show("Could not locate the accounting file for this school. Please contact an administrator for assistance.")
Exit Sub
End If
'open accounting file and check if it's read only, if so, another user is editing it so close it and tell the user to try again in a few seconds, if it's not read only, see next comment
StatVar.xlWBUnapprovedAcctFile = StatVar.xlApp.Workbooks.Open(UnapprovedAcctFile)
If StatVar.xlApp.ActiveWorkbook.ReadOnly = True Then 'check if file is read only, if so close it and exit sub
StatVar.xlApp.ActiveWorkbook.Close(False)
MessageBox.Show("The system is busy. Please try again in a few seconds.")
Exit Sub
End If
'search unapproved accounting file for ID (SSN-award year example: 555555555-13) - use searchString variable above
rng = StatVar.xlApp.ActiveWorkbook.Sheets("Sheet1").Range("BD2:BD30002").Find(searchString, , Excel.XlFindLookIn.xlValues, Excel.XlLookAt.xlWhole, Excel.XlSearchOrder.xlByRows, Excel.XlSearchDirection.xlNext, False)
'if searchString is found
If rng IsNot Nothing Then
rng.EntireRow.Select() 'select the row searchString was found in
'check if approved accounting file for this school exists, if not, create it
If Not IO.File.Exists(ApprovedAcctFile) Then
StatVar.xlApp.Workbooks.Add()
StatVar.xlApp.ActiveWorkbook.SaveAs(ApprovedAcctFile)
StatVar.xlApp.ActiveWorkbook.Close(True)
End If
StatVar.xlWBApprovedAcctFile = StatVar.xlApp.Workbooks.Open(ApprovedAcctFile) 'open the Approved file
If StatVar.xlApp.ActiveWorkbook.ReadOnly = True Then 'check if the Approved file is read only, if so, close it and exit sub because it needs to be writable
StatVar.xlApp.ActiveWorkbook.Close(False) 'close the Approved file, don't save changes
StatVar.xlApp.ActiveWorkbook.Close(False) 'close unapproved accounting file, don't save changes
MessageBox.Show("The system is busy. Please try again in a few seconds.")
Exit Sub
End If
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Columns("AV").NumberFormat = "@" 'format column AV of the Approved file as text so "13/14" remains formatted correctly
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Rows("1:1").Insert(Excel.XlInsertShiftDirection.xlShiftDown) 'insert a row at the top of the Approved file
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Rows("1:1").Value = rng.EntireRow.Value 'set the 1st row of the Approved file equal to the row selected earlier in the unapproved accounting file
StatVar.xlApp.ActiveWorkbook.ActiveSheet.UsedRange.RemoveDuplicates(Columns:=(56)) 'search column 56 in Approved file for duplicates and remove entire row if a duplicate ID is found
rng.EntireRow.Delete() 'delete row the searchString was found in from the unapproved accounting file
StatVar.xlApp.ActiveWorkbook.Close(True) 'close the Approved file, save changes
StatVar.xlApp.ActiveWorkbook.Close(True) 'close unapproved accounting file, save changes
'MessageBox.Show("Eureka!")
Else
'if searchString is not found, close unapproved accounting file, inform user and exit sub
StatVar.xlApp.ActiveWorkbook.Close(False)
MessageBox.Show("Could not locate this record on the accounting file. Your files were not deleted.")
Exit Sub
End If
'move selected file and corresponding non-Memo files to Publish folder
Dim filePath As String = "W:\TOM\ERIC\Award_Letters\Excel pre_publish\"
Dim movePath As String = "W:\TOM\ERIC\Award_Letters\Publish\"
Dim filenm As String
'check if each item in listbox contains the string extracted from the selected item via Excel formula; listbox select event sends the filename to Excel and a formula extracts the string to find in each listbox item...look for this string
For Each c In ListBoxPrePublish.Items
If c.ToString.Contains(StatVar.xlApp.Sheets("Cross Checking").Range("H6").Text) Then
'make sure the current listbox item in this loop is not a Memo, if it's not, move it
If Not c.ToString.Contains("-M.xls") Then
filenm = c
Dim FileToMove = filePath & filenm
Dim MoveToLocation = movePath & filenm
System.IO.File.Move(FileToMove, MoveToLocation)
ListBoxPublished.Items.Add(c) 'add files files that are being published to the published files listbox
End If
End If
Next
'refresh prepublish list, if user has a school selected, REMOVE all list items that don't contain the school code being generated via VLOOKUP in Excel using the school name from comboboxschool; look for this string in the loop surrounded with "-"
Call ListFiles()
If ComboBoxSchool.Text <> "" Then
For i As Integer = ListBoxPrePublish.Items.Count - 1 To 0 Step -1
'if current loop item does not contain the school code for the selected school, remove the item from the listbox
If Not ListBoxPrePublish.Items(i).Contains("-" & StatVar.xlApp.Sheets("Cross Checking").Range("E3").Text & "-") Then
ListBoxPrePublish.Items.RemoveAt(i)
End If
Next
End If
'refresh deleted files listbox
Call ListDeletedTodayFiles()
End If
End If
Catch exc As Exception
MessageBox.Show("Unable to publish the selected file. Please verify this file or any of its corresponding files are not open by you or another user. If the problem persists, contact an administrator for assistance." & vbNewLine & vbNewLine & "Error: " & exc.Message)
End Try
，或者這更好的？：（OPTION 2）
Try
'check if user has selected a file
If ListBoxPrePublish.SelectedItems.Count = 0 Then
MessageBox.Show("Please select a file to delete.")
Exit Sub
End If
'check if user has selected a Memo to publish, if so, move file to Publish folder; if user hasn't selected a Memo, move to next If statement
If ListBoxPrePublish.SelectedItem.Contains("-M.xls") Then
Dim resultMemo = MessageBox.Show("Are you sure you want to delete this Memo?", "", MessageBoxButtons.YesNo)
If resultMemo = DialogResult.Yes Then
Dim filePath As String = "W:\TOM\ERIC\Award_Letters\Excel pre_publish\"
Dim movePath As String = "W:\TOM\ERIC\Award_Letters\Publish\"
Dim filenm As String = ListBoxPrePublish.SelectedItem
Dim FileToMove = filePath & filenm
Dim MoveToLocation = movePath & filenm
'move the file
System.IO.File.Move(FileToMove, MoveToLocation)
ListBoxPublished.Items.Add(ListBoxPrePublish.SelectedItem)
ListBoxPrePublish.Items.Remove(ListBoxPrePublish.SelectedItem)
Exit Sub
Else
Exit Sub
End If
End If
Catch exc As Exception
MessageBox.Show("An error occured and the selected file was not published. Please contact an administrator if the problem continues." & vbNewLine & vbNewLine & "Error: " & exc.Message)
End Try
Try
'ask user if they're sure they want to publish selected file and corresponding files...remember, only if the selected item is not a Memo
Dim result = MessageBox.Show("This action will publish all corresponding files for the selected student except for Memos. Memos must be deleted individually. Do you want to continue?", "", MessageBoxButtons.YesNo)
If result = DialogResult.No Then
Exit Sub
Else
If result = DialogResult.Yes Then
'find ID for student in unapprovd accounting file, move the record to the Deleted Today file, delete record from unapproved accounting file
Dim UnapprovedAcctFile As String = "W:\TOM\ERIC\Award_Letters\Accounting Files\Unapproved\" & StatVar.xlApp.Sheets("New Calculator Input").Range("D30").Value & ".xlsx"
Dim ApprovedAcctFile As String = "W:\TOM\ERIC\Award_Letters\Accounting Files\Approved\" & StatVar.xlApp.Sheets("New Calculator Input").Range("D30").Value & " Import" & ".xlsx"
Dim searchString As String = StatVar.xlApp.Sheets("Cross Checking").Range("J6").Text 'this is the ID that will be searched for in the accounting file
Dim rng
'make sure accounting file for school exists
If Not IO.File.Exists(UnapprovedAcctFile) Then
MessageBox.Show("Could not locate the accounting file for this school. Please contact an administrator for assistance.")
Exit Sub
End If
'open accounting file and check if it's read only, if so, another user is editing it so close it and tell the user to try again in a few seconds, if it's not read only, see next comment
StatVar.xlWBUnapprovedAcctFile = StatVar.xlApp.Workbooks.Open(UnapprovedAcctFile)
If StatVar.xlApp.ActiveWorkbook.ReadOnly = True Then 'check if file is read only, if so close it and exit sub
StatVar.xlApp.ActiveWorkbook.Close(False)
MessageBox.Show("The system is busy. Please try again in a few seconds.")
Exit Sub
End If
'search unapproved accounting file for ID (SSN-award year example: 555555555-13) - use searchString variable above
rng = StatVar.xlApp.ActiveWorkbook.Sheets("Sheet1").Range("BD2:BD30002").Find(searchString, , Excel.XlFindLookIn.xlValues, Excel.XlLookAt.xlWhole, Excel.XlSearchOrder.xlByRows, Excel.XlSearchDirection.xlNext, False)
'if searchString is found
If rng IsNot Nothing Then
rng.EntireRow.Select() 'select the row searchString was found in
'check if approved accounting file for this school exists, if not, create it
If Not IO.File.Exists(ApprovedAcctFile) Then
StatVar.xlApp.Workbooks.Add()
StatVar.xlApp.ActiveWorkbook.SaveAs(ApprovedAcctFile)
StatVar.xlApp.ActiveWorkbook.Close(True)
End If
StatVar.xlWBApprovedAcctFile = StatVar.xlApp.Workbooks.Open(ApprovedAcctFile) 'open the Approved file
If StatVar.xlApp.ActiveWorkbook.ReadOnly = True Then 'check if the Approved file is read only, if so, close it and exit sub because it needs to be writable
StatVar.xlApp.ActiveWorkbook.Close(False) 'close the Approved file, don't save changes
StatVar.xlApp.ActiveWorkbook.Close(False) 'close unapproved accounting file, don't save changes
MessageBox.Show("The system is busy. Please try again in a few seconds.")
Exit Sub
End If
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Columns("AV").NumberFormat = "@" 'format column AV of the Approved file as text so "13/14" remains formatted correctly
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Rows("1:1").Insert(Excel.XlInsertShiftDirection.xlShiftDown) 'insert a row at the top of the Approved file
StatVar.xlApp.ActiveWorkbook.ActiveSheet.Rows("1:1").Value = rng.EntireRow.Value 'set the 1st row of the Approved file equal to the row selected earlier in the unapproved accounting file
StatVar.xlApp.ActiveWorkbook.ActiveSheet.UsedRange.RemoveDuplicates(Columns:=(56)) 'search column 56 in Approved file for duplicates and remove entire row if a duplicate ID is found
rng.EntireRow.Delete() 'delete row the searchString was found in from the unapproved accounting file
StatVar.xlApp.ActiveWorkbook.Close(True) 'close the Approved file, save changes
StatVar.xlApp.ActiveWorkbook.Close(True) 'close unapproved accounting file, save changes
'MessageBox.Show("Eureka!")
Else
'if searchString is not found, close unapproved accounting file, inform user and exit sub
StatVar.xlApp.ActiveWorkbook.Close(False)
MessageBox.Show("Could not locate this record on the accounting file. Your files were not deleted.")
Exit Sub
End If
'move selected file and corresponding non-Memo files to Publish folder
Dim filePath As String = "W:\TOM\ERIC\Award_Letters\Excel pre_publish\"
Dim movePath As String = "W:\TOM\ERIC\Award_Letters\Publish\"
Dim filenm As String
'check if each item in listbox contains the string extracted from the selected item via Excel formula; listbox select event sends the filename to Excel and a formula extracts the string to find in each listbox item...look for this string
For Each c In ListBoxPrePublish.Items
If c.ToString.Contains(StatVar.xlApp.Sheets("Cross Checking").Range("H6").Text) Then
'make sure the current listbox item in this loop is not a Memo, if it's not, move it
If Not c.ToString.Contains("-M.xls") Then
filenm = c
Dim FileToMove = filePath & filenm
Dim MoveToLocation = movePath & filenm
System.IO.File.Move(FileToMove, MoveToLocation)
ListBoxPublished.Items.Add(c) 'add files files that are being published to the published files listbox
End If
End If
Next
'refresh prepublish list, if user has a school selected, REMOVE all list items that don't contain the school code being generated via VLOOKUP in Excel using the school name from comboboxschool; look for this string in the loop surrounded with "-"
Call ListFiles()
If ComboBoxSchool.Text <> "" Then
For i As Integer = ListBoxPrePublish.Items.Count - 1 To 0 Step -1
'if current loop item does not contain the school code for the selected school, remove the item from the listbox
If Not ListBoxPrePublish.Items(i).Contains("-" & StatVar.xlApp.Sheets("Cross Checking").Range("E3").Text & "-") Then
ListBoxPrePublish.Items.RemoveAt(i)
End If
Next
End If
'refresh deleted files listbox
Call ListDeletedTodayFiles()
End If
End If
Catch exc As Exception
MessageBox.Show("Unable to publish the selected file. Please verify this file or any of its corresponding files are not open by you or another user. If the problem persists, contact an administrator for assistance." & vbNewLine & vbNewLine & "Error: " & exc.Message)
End Try
要麼是1這些方法比其他方法更好嗎？還是取決於我對我的程序做了什麼？很想聽到關於此的不同意見。
圍繞巨大的代碼塊嘗試/捕捉被廣泛認爲是一個非常糟糕的做法。 –
Try/catch塊很貴。儘量縮小範圍。這也使您能夠提供更精確的錯誤記錄，從而簡化調試過程。 –
你介意闡述爲什麼？我不是在質疑你，只是想了解「爲什麼」。如果你能指點我一個很好的鏈接，我會閱讀它，但我一直沒有找到關於這個主題的很多有用的文獻 –