所以我面對這個問題,我有2頁,ViewAccount和MainPage。列表框(不同頁面)上的NullReferenceException
在MainPage中有一個名爲SavedAccountsLst的ListBox。問題是,在ViewAccount頁面中,一旦我點擊一個按鈕,它會拋出一個NullReferenceException
。
這是我使用的ViewAccount代碼:
Private Sub Delete_Account_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Dim Storage As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()
Storage.DeleteFile("SafeLockPLUS/SavedAccounts/" & PageTitle.Text)
MessageBox.Show(PageTitle.Text & " has been deleted.", "Deleted", MessageBoxButton.OK)
Dim aa = TryCast(DirectCast(Application.Current, App).RootFrame.Content, MainPage)
aa.SavedAccountslst.ItemsSource = Nothing
Dim directory As String = "./SafeLockPLUS/SavedAccounts/*.*"
Dim filenames As String() = Storage.GetFileNames(directory)
aa.SavedAccountslst.ItemsSource = filenames
NavigationService.GoBack()
End Sub
那是什麼意思做的是,它會刪除從viewaccount頁面文件並清除SavedAccountList的項目,並重新加載它們都在ViewAccount頁面,然後返回。
哪一行正是引發異常得空? –
aa.SavedAccountslst.ItemsSource = Nothing –
如果你在ViewAccount中,那麼'App.RootFrame.Content'是'ViewAccount',而不是'MainPage',因此錯誤 –